Electrochemical synthesis of pyrazolines and pyrazoles

Abstract

The present invention relates to an electrochemical process for the synthesis of pyrazolines and pyrazoles of formula (I). The process can be especially used for the synthesis of the herbicide safener mefenpyr-diethyl.

Description

[0001] Electrochemical Synthesis of Pyrazolines and Pyrazoles Technical Field The present invention relates to an electrochemical process for the synthesis of pyrazolines and pyrazoles. The process can be used in particular for the synthesis of the herbicide safener mefenpyr-diethyl. State of the Art Pyrazolines and pyrazoles are essential building blocks of complex agrochemical or pharmaceutical compounds and are therefore highly relevant for industrial applications. Various processes for the synthesis of pyrazolines and pyrazoles are described in the prior art. For example, their preparation by [3+2] cycloaddition starting from the corresponding hydrazonoyl halides using bases is known. However, the hydrazonoyl halides required for this purpose must be prepared in a complex manner, sometimes using toxic and costly halogenating reagents (WO 2010 / 127855).In addition, α,β-unsaturated ketones can be converted organocatalytically with hydrazines to the corresponding pyrazolines. However, this requires anhydrous operation and the use of complex catalyst systems and toxic halogenated solvents. Furthermore, several methods are known that enable the enantioselective preparation of pyrazolines from alkyne components. These utilize costly transition metal catalysts based on palladium, titanium, copper, and iridium, some of which feature complex ligand systems. The known methods are generally characterized by the use of expensive transition metals, superstoichiometric amounts of (auxiliary) reagents, complex substrate syntheses or multi-step synthesis sequences, and the use of chemical halogenating agents, usually as an excess component.The increased material input and the use of toxic solvents lead to increased reagent waste, which must be disposed of in a complex and costly manner and counteracts the economic viability of the methods. Therefore, there is a need for synthesis processes for pyrazoles and pyrazolines that are less costly, material-intensive, and time-consuming. The object of the present invention is therefore to provide novel synthesis processes that do not have the above-mentioned disadvantages. Brief Summary of the Invention This object is at least partially achieved by a process for preparing compounds of general formula (I) 2 wherein. ht; R 1 is alkyl, -C(O)O-alkyl, cycloalkyl, aryl, or heterocyclyl, each substituted or unsubstituted; R 2 is alkyl, -C(O)O-alkyl, cycloalkyl, aryl, or heterocyclyl, each substituted or unsubstituted; R 3is alkyl, -C(O)O-alkyl, -C(O)O-aryl, -C(O)N-(alkyl)2, -CN, -P(O)(O-alkyl)2, cycloalkyl, aryl, or heterocyclyl, each substituted or unsubstituted, or H; R 4 exists if represents a single bond and R 4 is alkyl, -C(O)O-alkyl, -C(O)O-aryl, cycloalkyl, aryl, or heterocyclyl, each substituted or unsubstituted, or H; or R 3 and R 4 together with the carbon atom in the compounds of formula (I), the R 3 and R 4 a substituted or unsubstituted cycloalkyl or heterocyclyl; R 5 is alkyl, -C(O)O-alkyl, cycloalkyl, aryl, or heterocyclyl, each substituted or unsubstituted, or H; or R 4 and R 5 together with the carbon atoms, the R 4 and R 5 in the compounds of formula (I) are a substituted or unsubstituted cycloalkyl or heterocyclyl; or R1 and R 5 together with the carbon atoms in the compounds of formula (I) which R 1 and R 5 connect, a substituted or unsubstituted cycloalkyl or heterocyclyl; characterized in that compounds of the general formula (II) where R 1 and R 2 have the same meaning as in the general formula (I), in the presence of an iodide source electrochemically with a compound of formula (III) or (IV), where R 3 , R 4 and R 5 have the same meaning as in the general formula (I). \ Here for a cis- or trans-isomer in compounds of formula (III), ie R 3 and R 5 can be in cis- or trans-configuration to each other, or R 4 and R 5are in cis or trans configuration. In particular, the present invention relates to a process for the preparation of compounds of general formula (Ia) with R 1 is alkyl, -C(O)O-alkyl, cycloalkyl, aryl, or heterocyclyl, each substituted or unsubstituted; R 2 is alkyl, -C(O)O-alkyl, cycloalkyl, aryl, or heterocyclyl, each substituted or unsubstituted; R 3 is alkyl, -C(O)O-alkyl, -C(O)O-aryl, -C(O)N-(alkyl)2, -CN, -P(O)(O-alkyl)2, cycloalkyl, aryl, or heterocyclyl, each substituted or unsubstituted, or H; R 4 is alkyl, -C(O)O-alkyl, -C(O)O-aryl, cycloalkyl, aryl, or heterocyclyl, each substituted or unsubstituted, or H; or R 3 and R 4 together with the carbon atom in the compounds of formula (I), the R 3 and R 4 a substituted or unsubstituted cycloalkyl or heterocyclyl; R 5is alkyl, -C(O)O-alkyl, cycloalkyl, aryl, or heterocyclyl, each substituted or unsubstituted, or H; or R 4 and R 5 together with the carbon atoms, the R 4 and R 5 in the compounds of formula (I) are a substituted or unsubstituted cycloalkyl or heterocyclyl; or R 1 and R 5 together with the carbon atoms in the compounds of formula (I) which R 1 and R 5 connect, a substituted or unsubstituted cycloalkyl or heterocyclyl; characterized in that compounds of the general formula (II) where R 1 and R 2 have the same meaning as in the general formula (Ia), in the presence of an iodide source, electrochemically with a compound of the formula (III) 3 where R 3 , R 4 and R 5have the same meaning as in the general formula (I). The radicals alkyl, -C(O)O-alkyl, -C(O)N-(alkyl)2, -C(O)O-aryl, cycloalkyl, aryl, or heterocyclyl for R 1 to R 5can be independently substituted with various substituents. The present invention provides an electrochemical method for the direct synthesis of pyrazolines and pyrazoles from hydrazones and alkenes or alkynes. The substrates required for the reaction can be synthesized from basic chemicals by simple condensation reactions, creating a value chain that eliminates the need for environmentally harmful transition metals, halogenating agents, and toxic solvents. The iodide source is efficiently used in a dual function as a conductive salt and mediator, thus minimizing the generation of costly reagent waste. The products can be easily purified, and the reagents used in excess of stoichiometric amounts can be recycled, further contributing to the economic viability and sustainability of the process.The present invention therefore enables simple, efficient, and sustainable electrochemical access to a library of synthetically relevant pyrazolines and pyrazoles. R is preferred, alone or in combination. 1 unsubstituted or substituted C1-C6 alkyl, unsubstituted or substituted -C(O)O(C1-C8 alkyl), unsubstituted or substituted C3-C12 cycloalkyl, unsubstituted or substituted phenyl, unsubstituted or substituted naphthyl. Preference is given, alone or in combination, to R 2 unsubstituted or substituted C1-C6 alkyl, unsubstituted or substituted -C(O)O(C1-C8 alkyl), unsubstituted or substituted C3-C12 cycloalkyl, unsubstituted or substituted phenyl. R is preferred, alone or in combination. 3H, unsubstituted or substituted C1-C6-alkyl, unsubstituted or substituted -C(O)O(C1-8-alkyl), unsubstituted or substituted -C(O)O-phenyl, unsubstituted or substituted -C(O)O-benzyl, unsubstituted or substituted C3-C12-cycloalkyl, unsubstituted or substituted phenyl, unsubstituted or substituted naphthyl. Preference is given, provided represents a single bond, alone or in combination, R 4 H, unsubstituted or substituted C1-C6-alkyl, unsubstituted or substituted -C(O)O(C1-C8-alkyl), unsubstituted or substituted -C(O)O-phenyl, unsubstituted or substituted -C(O)O-benzyl, unsubstituted or substituted C3-C12-cycloalkyl, unsubstituted or substituted phenyl. Alternatively, R 3 and R 4 together with the carbon atom in the compounds of formula (I), the R 3 and R 4connects a substituted C3-C 12 -cycloalkyl or heterocyclyl. Preferably, alone or in combination, R 5 H, unsubstituted or substituted C1–C6 alkyl, unsubstituted or substituted -C(O)O(C 1- 8-alkyl), C3-C 12 -Cycloalkyl, substituted or unsubstituted phenyl. Alternatively, R 1 and R 5 together with the carbon atoms in the compounds of formula (I) containing R 1 and R 5 connect a substituted C3-C 12 -cycloalkyl or heterocyclyl. Alternatively, R 4 and R 5 together with the carbon atoms that R 4 and R 5 connect with each other, a C3-C 12 -cycloalkyl or heterocyclyl. If R 1 and R 5 form a ring system, preferably no ring system is replaced by R 3 and R 4formed, and vice versa. Further preferred, alone or in combination, is R 1 C1-C4-alkyl, -C(O)O(C1-4-alkyl), C3-C8-cycloalkyl, phenyl, mono- or poly-C1-C4-alkyl-substituted phenyl, mono- or poly-halogen-substituted phenyl, mono- or poly-nitro-substituted phenyl, mono- or poly-cyano-substituted phenyl, mono- or poly-C(O)O(C1-4-alkyl)-substituted phenyl, or naphthyl. In particular, R 1 -C(O)OCH2CH3. More preferably, alone or in combination, R 2 C1-C4-alkyl, -C(O)O(C1-4-alkyl), C3-C8-cycloalkyl, phenyl, mono- or poly-C1-C4-alkyl-substituted phenyl, mono- or poly-halogen-substituted phenyl, mono- or poly-nitro-substituted phenyl, mono- or poly-cyano-substituted phenyl, mono- or poly-C(O)O(C1-4-alkyl)-substituted phenyl, mono- or poly-sulfo-substituted phenyl, or naphthyl. In particular, R 2a dichlorophenyl. More preferably, alone or in combination, R 3 C1-C4-alkyl, -C(O)O(C1-4-alkyl), C3-C8-cycloalkyl, phenyl, mono- or poly-C1-C4-alkyl-substituted phenyl, mono- or poly-halogen-substituted phenyl, mono- or poly-nitro-substituted phenyl, mono- or poly-cyano-substituted phenyl, mono- or poly-C(O)O(C1-4-alkyl)-substituted phenyl, or naphthyl. In particular, R 3 CH3. Further preferred is, if represents a single bond, alone or in combination, R 4 H, C1–C4 alkyl, -C(O)O(C 1-4-alkyl), mono- or poly-C1-C4-alkyl-substituted -C(O)O-benzyl, mono- or poly-C1-C4-alkyl-substituted C(O)O-phenyl, C3-C8-cycloalkyl, phenyl, mono- or poly-C1-C4-alkyl-substituted phenyl, mono- or poly-halogen-substituted phenyl, mono- or poly-nitro-substituted phenyl, mono- or poly-cyano-substituted phenyl, or mono- or poly-C(O)O(C 1-4 -alkyl)-substituted phenyl. In particular, R 4 -C(O)O(C 1-4 -alkyl)), mono- or poly-C1-C4-alkyl-substituted C(O)O-benzyl, or mono- or poly-C1-C4-alkyl-substituted C(O)O-phenyl. More preferably, R 4 -C(O)OCH2CH3. More preferably, alone or in combination, R 5 H, C1–C4 alkyl, C(O)O(C 1-4 -alkyl), C3-C 10-Cycloalkyl, phenyl, mono- or poly-C1-C4-alkyl-substituted phenyl, mono- or poly-halogen-substituted phenyl, mono- or poly-nitro-substituted phenyl, mono- or poly-cyano-substituted phenyl, or mono- or poly-C(O)O(C 1-4 -alkyl)-substituted phenyl. In particular, R 5H. The iodide source is preferably used in the form of sodium iodide, lithium iodide or potassium iodide or a mixture thereof. The use of sodium iodide, lithium iodide or potassium iodide in the dual role of mediator and conducting salt is resource-saving and enables efficient and simple recycling. In contrast, the electrochemical processes known in the prior art require a higher material input due to the separate roles of electrochemical mediator and conducting salt, which counteracts the economic viability of the known methods. Sodium iodide is particularly preferred. The iodide source can be in an aqueous solution, an organic solvent, a solvent mixture of two or more organic solvents, or a two-phase mixture of an aqueous solution and an organic solvent or a solvent mixture of two or more organic solvents.In one embodiment of the present invention, the iodide source is present in a two-phase mixture of an aqueous solution and an organic solvent or a solvent mixture of two or more organic solvents. The iodide source is used in a concentration of 0.2 to 2.0 M, based on the aqueous solution; more preferably in a concentration of 0.5 to 1.4 M, based on the aqueous solution; in particular in a concentration of 0.8 to 1.4 M, based on the aqueous solution. The organic solvent is preferably selected from ethyl acetate, tert-butyl methyl ether, dichloromethane, chlorobenzene, 1,2-dichloroethane, or mixtures thereof. Ethyl acetate and / or tert-butyl methyl ether are particularly preferred as the organic solvent. In an alternative embodiment, the iodide source is present in an aqueous solution without the addition of an organic solvent.Here, the iodide source is used in a concentration of 0.2 to 2.0 M, based on the aqueous solution; more preferably in a concentration of 0.5 to 1.4 M, based on the aqueous solution; in particular in a concentration of 0.8 to 1.4 M, based on the aqueous solution. In a further alternative embodiment, the iodide source is present in an organic solvent or a solvent mixture of two or more organic solvents without the addition of water. Here, the iodide source is used in a concentration of 0.2 to 4.0 M, based on the organic solvent or solvent mixture; more preferably in a concentration of 0.5 to 3.5 M, based on the organic solvent or solvent mixture; in particular in a concentration of 0.8 to 3.0 M, based on the organic solvent or solvent mixture.The organic solvent is preferably selected from ethanol, acetonitrile, ethyl acetate, tert-butyl methyl ether, dichloromethane, chlorobenzene, 1,2-dichloroethane, or mixtures thereof. Particular preference is given to a mixture of ethanol and acetonitrile as the organic solvent mixture, preferably in a mixing ratio of 1:10 to 10:1, more preferably 1:5 to 5:1, especially preferably 1:2 to 2:1 (vol / vol). Compound (III) or (IV) is preferably used in amounts between 1.0 and 6.0 equivalents, based on the total amount of compounds of formula (II) used, more preferably between 2.0 and 5.0 equivalents. The reaction is preferably carried out in an undivided electrolysis cell. Graphite electrodes are preferably used as the anode and cathode. The process according to the invention is thus cost-effective in terms of the electrode material and the structure in a simple cell.Isostatic graphite is preferably used. The process is preferably carried out at a current density of 20 to 50 mA / cm², more preferably at a current density of 30 to 40 mA / cm². The process is preferably carried out until an applied charge of 1 to 10 F, more preferably 2 to 6 F, is reached. The reaction is preferably carried out at a temperature of 10 to 50 °C, preferably 20 to 40 °C. These reaction conditions improve the yield of the pyrazole or pyrazoline. The aqueous phase, if used, is preferably subsequently separated and freeze-dried to recover the iodide source. Alternatively, the aqueous phase can be separated and used without further processing to carry out a further reaction step or a process according to the present invention. Recycling the iodide source or the aqueous phase allows for a particularly environmentally friendly production of the compounds.Preferably, the compound (I) or (Ia) is represented by diethyl 1-(2,4-dichlorophenyl)-5-methyl-4,5-dihydro-1H-pyrazole-3,5-dicarboxylate (mefenpyr-diethyl; CAS number 135590-91-9), the compound (II) is represented by ethyl 2-(2-(2,4-dichlorophenyl)hydrazono)acetate; and the compound (III) is represented by ethyl methacrylate, with R. 1 -C(O)O-Ethyl; R 2 2,4-dichlorophenyl; R 3 CH3; R 4 -C(O)O-Ethyl; R 5 H. Compounds of formula (II) can generally exist as racemates or as (E) or (Z) isomers, ie with II-a, 25 where represents a cis- or trans-isomer. One of the isomers can preferably be reacted in the process according to the invention. In this respect, in further embodiments of the present invention, the yield of the synthesis can be increased by using one of the possible isomers of the general formula (II-a). Particular preference is given to the compound (I) or (Ia) represented by diethyl 1-(2,4-dichlorophenyl)-5-methyl-4,5-dihydro-1H-pyrazole-3,5-dicarboxylate (mefenpyr-diethyl), the compound (II) represented by (Z)-ethylglyoxylate-2,5-dichlorophenylhydrazone; and the compound (III) represented by ethyl methacrylate, with R 1 -C(O)O-Ethyl; R 2 2,4-dichlorophenyl; R 3 CH3; R 4 -C(O)O-Ethyl; R 5 H.

[0002] Detailed Description of the Invention The process according to the invention allows for an efficient reaction in a two-phase solvent system consisting of water and an organic solvent. An iodide source, preferably sodium iodide, is used as both a conducting salt and an electrochemical mediator. Carrying out the reaction in an undivided electrolysis cell using galvanostatic operation with a simple cell design (two-electrode arrangement) enables scalable reaction conditions. The possibility of recycling the mediator and the unreacted excess dipolarophile contributes to the sustainability and economic viability of the process. In particular, high yields of the herbicide safener mefenpyr-diethyl of 73% were achieved using the process according to the invention. The terms used here are familiar to those skilled in the art.The following definitions are used: For the purposes of the present invention, the term "alkyl" encompasses saturated hydrocarbon radicals which may be branched or straight-chain and unsubstituted or at least monosubstituted. Suitable alkyl radicals which may be unsubstituted or mono- or polysubstituted include, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, 2-butyl, tert-butyl, n-pentyl, 2-pentyl, 3-pentyl, isopentyl, neopentyl, n-hexyl, 2-hexyl, 3-hexyl, n-heptyl, n-octyl, -C(H)(C2H5)2, -C(H)(n-C3H7)2 and -CH2-CH2-C(H)(CH3)-(CH2)3-CH3. The term “cycloalkyl” means an optionally substituted carbocyclic, saturated ring system with preferably 3-12, more preferably 3-8 ring C atoms, e.g. cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl.In the case of optionally substituted cycloalkyl, cyclic systems with substituents are encompassed, including substituents with a double bond on the cycloalkyl radical, e.g., an alkylidene group such as methylidene. In the case of optionally substituted cycloalkyl, polycyclic aliphatic systems are also encompassed, such as bicyclo[1.1.0]butan-1-yl, bicyclo[1.1.0]butan-2-yl, bicyclo[2.1.0]pentan-1-yl, bicyclo[2.1.0]pentan-2-yl, bicyclo[2.1.0]pentan-5-yl, bicyclo[2.2.1]hept-2-yl (norbornyl), bicyclo[2.2.2]octan-2-yl, adamantan-1-yl, and adamantan-2-yl. In the case of substituted cycloalkyl, spirocyclic aliphatic systems are also included, such as spiro[2.2]pent-1-yl, spiro[2.3]hex-1-yl, spiro[2.3]hex-4-yl, 3-spiro[2.3]hex-5-yl.The term "aryl" in the context of the present invention means a mono- or polycyclic, preferably a mono- or bicyclic, aromatic hydrocarbon radical having preferably 6, 10, or 14 carbon atoms. An aryl radical may be unsubstituted or monosubstituted or polysubstituted by identical or different substituents. Suitable aryl radicals include, for example, phenyl, 1-naphthyl, 2-naphthyl, and anthracenyl. The term "heterocyclyl" in the context of the present invention means a mono- or polycyclic system having 3 to 20 ring atoms, preferably 3 to 14 ring atoms, particularly preferably 3 to 10 ring atoms, comprising C atoms and 1, 2, 3, 4, or 5 heteroatoms, in particular nitrogen, oxygen, and / or sulfur, where the heteroatoms may be identical or different. The cyclic system may be saturated or mono- or polyunsaturated.The term "heterocyclyl" encompasses aliphatic and aromatic ring systems (heteroaryls) and combinations thereof, including systems in which an aromatic ring is part of a bi- or polycyclic saturated, partially unsaturated, and / or aromatic system. Examples of suitable heterocycles are pyrrolidinyl, thiapyrrolidinyl, piperidinyl, piperazinyl, oxapiperazinyl, oxapiperidinyl, oxadiazolyl, tetrahydrofuryl, imidazolidinyl, thiazolidinyl, tetrahydropyranyl, morpholinyl, tetrahydrothiophenyl, and dihydropyranyl.Als geeignete Heteroaryl-Reste seien beispielsweise Indolizinyl, Benzimidazolyl, Tetrazolyl, Triazinyl, Isoxazolyl, Phthalazinyl, Carbazolyl, Carbolinyl, Diaza-naphthyl, Thienyl, Furyl, Pyrrolyl, Pyrazolyl, Pyrazinyl, Pyranyl, Triazolyl, Pyridinyl, Imidazolyl, Indolyl, Isoindolyl, Benzo[b]furanyl, Benzo[b]thiophenyl, Benzo[d]thiazolyl, Benzodiazolyl, Benzotriazolyl, Benzoxazolyl, Benzisoxazolyl, Thiazolyl, Thiadiazolyl, Oxazolyl, Oxadiazolyl, Isoxazolyl, Pyridazinyl, Pyrimidinyl, Indazolyl, Chinoxalinyl, Chinazolinyl, Chinolinyl, Naphthridinyl und Isochinolinyl genannt. Beispielhaft für Aryl-Reste, die mit einem mono- bzw. bizyklischen Ringsystem kondensiert sind und ebenfalls unter den Begriff „Heterozyklus“ bzw.„Heterocyclyl“ fallen, seien (2,3)- Dihydrobenzo[b]thiophenyl, (2,3)-Dihydro-1H-indenyl, Indolinyl, (2,3)-Dihydrobenzofuranyl, (2,3)- Dihydrobenzo[d]oxazolyl, Benzo[d][1,3]dioxolyl, Benzo[d][1,3]oxathiolyl, Isoindolinyl, (1,3)- Diyhydroisobenzofuranyl, (1,3)-Dihydrobenzo[c]thiophenyl, (1,2,3,4)-Tetrahydronaphthyl, (1,2,3,4)- Tetrahydrochinolinyl, Chromanyl, Thiochromanyl, (1,2,3,4)-Tetrahydroisochinolinyl, (1,2,3,4)- Tetrahydrochinoxalinyl, (3,4)-Dihydro-2H-benzo[b][1,4]oxazinyl, (3,4)-Dihydro-2H- benzo[b][1,4]thiazinyl, (2,3)-Dihydro-benzo[b][1,4]dioxinyl, (2,3)-Dihydrobenzo[b][1,4]oxathiinyl, (6,7,8,9)-Tetrahydro-5H-benzo[7]annulenyl, (2,3,4,5)-Tetrahydro-1H-benzo[b]azepinyl und (2,3,4,5)- Tetrahydro-1H-benzo[c]azepinyl genannt.If one of the above-mentioned radicals is mono- or polysubstituted, suitable substituents are all those familiar to the person skilled in the art, preferably those which are independently selected from the group consisting of F, Cl, Br, I, -NO2, -CN, -OH, -SH, -NH2, -O-alkyl, -phenyl, -benzyl, alkyl-substituted phenyl or benzyl, -N(C. 1-5 -Alkyl)2, -N(C 1-5 -Alkyl)(Phenyl), -N(C 1-5 -Alkyl)(CH2- Phenyl), -N(C 1-5 -Alkyl)(CH2-CH2-Phenyl), -NH-C(=O)-OC 1-5 -Alkyl, -C(=O)-H, -C(=O)-C 1-5 -Alkyl, - 35 C(=O)-Phenyl, -C(=S)-C 1-5 -Alkyl, -C(=S)-Phenyl, -C(=O)-OH, -C(=O)-OC 1-5 -Alkyl, -C(=O)-O-Phenyl, -C(=O)-NH2, -C(=O)-NH-C 1-5 -Alkyl, -C(=O)-N(C 1-5 -Alkyl)2, -S(=O)-C 1-5 -Alkyl, -S(=O)- Phenyl, -S(=O)2- C 1-5 -Alkyl, -S(=O)2-Phenyl, -S(=O)2-NH2, -SO3H and -Si(C 1-5-Alkyl). Examples The following examples illustrate the present invention without, however, limiting it. Starting materials and protocols: Analytical-grade chemicals were purchased and used from common suppliers such as TCI, Aldrich, and Acros. The hydrazones used in the electrosynthesis were prepared from the corresponding aldehydes and hydrazines or hydrazine hydrochlorides according to literature-based synthesis procedures (PG Baraldi, S. Baraldi, G. Saponaro, M. Aghazadeh Tabrizi, R. Romagnoli, E. Ruggiero, F. Vincenzi, PA Borea, K. Varani, Journal of medicinal chemistry 2015, 58, 5355–5360; W. Wu, X. Yuan, J. Hu, X. Wu, Y. Wei, Z. Liu, J. Lu, J. Ye, Organic letters 2013, 15, 4524–4527). Isostatic graphite (Cgr, Sigrafine™ V2100, SGL Carbon, Bonn, Germany) was used as electrode material.These were treated with sandpaper (grain size 1000 + 1200, Bosch, Stuttgart, Germany) before conducting the experiment, and the surface was subsequently cleaned with a paper towel. Liquid chromatography was performed on Silica Gel 60 M (40-63 µm, Machery-Nagel GmbH & Co., Düren, Germany) using a Büchi Sepacore system and Büchi Control Unit C 620, Büchi UV photometer C 635, Büchi Fraction Collector C 660, and two Büchi Pump Modules C 605 (Büchi-Labortechnik GmbH, Essen, Germany) or using a packed PURIFLASH C18-HP 30 UM F0080 silica column (Interchim, Montluçon Cedex, France) with the previously described Büchi Sepacore system.High-performance liquid chromatography was performed on a Shimadzu HPLC-MS equipped with a SIL 20A HT autosampler, a CTO-20AC column oven, two LC-20AD pump modules for eluent gradient adjustment, an SPD-M20A diode array detector, a CBM-20A system controller, and a Eurospher II 100-5 C18 column (150 x 4 mm, Knauer, Berlin). Eluent: acetonitrile / water or acetonitrile / water / formic acid (1 vol%). NMR spectrometry of 1H NMR, 13C NMR, 15N NMR, 19F NMR, and 31P NMR spectra, as well as all 2D NMR spectra, were recorded at 25 °C using a Bruker Avance II HD 300 or Bruker Avance 30 III HD 400 (400 MHz, 5 mm BBFO head with z-gradient and ATM, SampleXPress 60 sample changer, Analytische Messtechnik, Karlsruhe, Germany) in CDCl3, DMSO-d6, CD2Cl2, CD3CN, (CD3)2CO, or CD3OD. 1H and 13C NMR spectra were referenced to the solvent residue signal.Mass spectrometry by electrospray ionization (ESI+ / -) or atmospheric pressure chemical ionization (APCI+ / -) was performed using an Agilant 6545 QTOF-MS (Agilant, Santa Clara (CA), USA). Electrolysis was carried out in temperature-controlled double-walled glass cells (SynLectro™, Merck KGaA, Darmstadt, Germany) equipped with a stirrer. Scale-up experiments were performed in a 300 mL double-walled glass cell. TDK-Lambda Z+ series galvanostats (TDK-Lambda UK Limited, Devon, UK) were used as the power source. Two synthesis methods according to the invention were used, variants A and B, which are explained below: Synthesis Method Variant A: A hydrazone (3 mmol, 1 eq.) and the corresponding alkene or alkyne (8.1 mmol, 2.7 eq.) were placed in a 50 mL beaker-type electrolysis cell with a temperature-controlled jacket and a cross-shaped magnetic stir bar. Ethyl acetate (5 mL) and 1 M aqueous sodium iodide solution (20 mL) were added.Galvanostatic electrolysis was carried out at 35 mA / cm² using isostatic graphite (60 × 20 × 3 mm, immersion depth 2.7 cm, active electrode area 5.4 cm²) as anode and cathode at 25 °C and a stirring speed of 1000 rpm until an applied charge of 5 F (1447 °C) was reached. The two-phase mixture was then transferred to a separatory funnel, and the phases were separated. The aqueous phase was extracted with ethyl acetate (1 × 30 mL), the combined organic phases were dried over magnesium sulfate, filtered, and the solvent was removed under reduced pressure. Further purification was carried out by column chromatography. Synthesis Procedure Variant B: A hydrazone (3.2 mmol, 1 eq.) and the corresponding alkene or alkyne (12.5 mmol, 3.9 eq.) were placed in a 50 mL beaker-type electrolysis cell with a temperature-controlled jacket and a cross-shaped magnetic stir bar. Tert-butyl methyl ether (5 mL) and 1 M aqueous sodium iodide solution (20 mL) were added.Galvanostatic electrolysis was carried out at 32.1 mA / cm² using isostatic graphite (60 × 20 × 3 mm, immersion depth 2.7 cm, active electrode area 5.4 cm²) as the anode and cathode at 32 °C and a stirring speed of 1000 rpm until an applied charge of 2.58 F (797 °C) was reached. The two-phase mixture was then transferred to a separatory funnel, and the phases were separated. The aqueous phase was extracted with ethyl acetate (1 × 30 mL), the combined organic phases were dried over magnesium sulfate, filtered, and freed from the solvent under reduced pressure. Further purification was carried out by column chromatography. Synthesis Products: According to variant A of the inventive synthesis process, the agrochemically relevant herbicide safener mefenpyr-diethyl was prepared in a very good yield of 73% (Scheme 1). g rlICg r CI 2.7Aq.Ethylmethacrylate 173% Mefenpyr-diethyl Scheme 1: Preparation of mefenpyr-diethyl. Also according to the inventive synthesis process variant A, ethyl glyoxalate phenylhydrazone was reacted with various alkenes and alkynes to give the corresponding pyrazolines and pyrazoles (see Scheme 2). Polymerization-sensitive alkenes such as styrene (2), acrylates (12, 13, 14), acrylonitrile (15), and acrylamide (16) can be used in the inventive process. Silyl-containing alkenes (27) and vinylphosphonates (11), as well as various cycloaliphatics (22–25), can also be successfully reacted. Halogen tolerance was also demonstrated by derivative 29. The results are summarized in Scheme 2. Analogously, according to the inventive synthesis process variant B, various benzaldehyde-based hydrazones and derivatives of aliphatic aldehydes were reacted to give the corresponding pyrazoles and pyrazolines (Scheme 3).Particularly, comparatively electron-poor benzaldehyde derivatives could be obtained in good yields. p-Nitro derivative (44) could also be prepared in 53% yield. An intramolecular cyclization of a comparatively electron-rich derivative was also achieved in a good yield of 53%. In addition to various aromatic aldehydes, aliphatic aldehydes could also be converted. The corresponding pyrazolines were obtained in yields of 23–38%. The results are summarized in Scheme 3. Furthermore, the application of the reaction according to variants A and B of the inventive synthesis process was tested on hydrazones derived from various hydrazines using styrene as the dipolarophile 25 (Scheme 4). Both electron-poor and electron-rich hydrazones could be converted in yields of up to 93% (Example 54). The results are summarized in Scheme 4.

[0003] Ph Scheme 2: Reaction of various dipolarophiles with glyoxalic acid ethyl ester phenylhydrazone.

[0004] Cgr lICw Scheme 3: Product spectrum of the various benzaldehyde-based pyrazolines. C g rlICgr Scheme 4: Product spectrum of the various hydrazine derivatives. The individual syntheses of Schemes 1 to 4 are described in detail below. Example 1: Diethyl 1-(2,4-dichlorophenyl)-5-methyl-4,5-dihydro-1H-pyrazole-3,5-dicarboxylate (Mefenpyr-diethyl) CI Synthesis according to synthetic method variant A using ethyl 2-(2-(2,4-dichlorophenyl)hydrazono)acetate (3 mmol, 783 mg, 1 eq.) and ethyl methacrylate (8.1 mmol, 925 mg, 2.7 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 4% EtOAc), the pyrazoline was obtained as an orange oil (2.28 mmol, 820 mg, 73%). 1H-NMR (400 MHz, CDCl3), δ / ppm: 7.41(d, J = 2.1 Hz, 1H, H-3'), 7.25–7.19 (m, 2H, H-5', H-6'), 4.33 (qd, J = 7.2, 1.7 Hz, 2H, H-2''), 4.19 (q, J = 7.2 Hz, 2H, H-2'''), 3.73 (d, J = 17.7 Hz, 1H, (H-4)'), 3.12 (d, J = 17.7 Hz, 1H, (H-4)''), 1.46 (s, 3H, H-1''''), 1.35 (t, J = 7.1 Hz, 3H, H-3''), 1.24 (t, J = 7.1 Hz, 3H, H-3'''). 1 3 C-NMR (101 MHz, CDCl3), δ / ppm: 171.5, 162.3, 140.1, 138.0, 133.6, 133.4, 130.5, 130.2, 127.5, 73.6, 62.3, 61.5, 45.1, 22.1, 14.5, 14.1. HRMS (ESI+), m / z: calculated for [C16H18 35 Cl2N2O4 + H] + 373.0716, found 373.0718; calculated for [C16H18 35 Cl 37 ClN2O4 + H]+ 375.0690, found 375.0692; calculated for [C16H18 37 Cl2N2O4 + H] + 377.0669, found 377.0674. Example 2: Ethyl 1,5-diphenyl-4,5-dihydro-1H-pyrazole-3-carboxylate 20 Synthesis according to synthetic method variant A using ethyl 2-(2-phenylhydrazono)acetate (3.9 mmol, 750 mg, 1 eq.) and styrene (10.5 mmol, 1097 mg, 2.7 eq.). A charge of 5.4 F (2032 C) was applied. After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 3% EtOAc), the pyrazoline was obtained as a yellow solid (3.02 mmol, 890 mg, 77%). 1H-NMR (400 MHz, CDCl3), δ / ppm: 7.35–7.16 (m, 7H, H-3', H-2''', H-3''', H-4'''), 7.10 (dt, J = 7.9, 1.3 Hz, 2H, H-2'), 6.87 (tt, J = 7.2, 1.2 Hz, 1H, H-4'), 5.42 (dd, J = 13.3, 7.0 Hz, 1H, H-5), 4.34 (q, J = 7.1 Hz, 2H, H-2''), 3.72 (dd, J = 18.0, 13.3 Hz, 1H, (H-4)'), 3.05 (dd, J = 18.0, 7.0 Hz, 1H, (H-4)''), 1.37 (t, J = 7.1 Hz, 3H, H-3''). 1 3C NMR (101 MHz, CDCl3), δ / ppm: 162.9, 142.7, 141.3, 138.3, 129.4, 129.1, 128.1, 125.8, 121.4, 114.7, 65.5, 61.4, 42.4, 14.5. HRMS (APCI+), m / z: calculated for [C18H18N2O2 + H] +295.1441, found 295.1447. Recycling of sodium iodide: Synthesis according to synthetic procedure variant A using ethyl 2-(2-phenylhydrazono)acetate (3 mmol, 577 mg, 1 eq.) and styrene (8.1 mmol, 844 mg, 2.7 eq.). Sodium iodide recovered by freeze-drying the aqueous phase from the reaction mixture for the synthesis of pyrazoline 32 was used. After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 3% EtOAc), the pyrazoline was obtained as a yellow solid (2.40 mmol, 707 mg, 80%). Scale-up (47 mmol): Analogous to synthesis procedure variant A, ethyl 2-(2-phenylhydrazono)acetate (46.8 mmol, 9.0 g, 1 eq.) and styrene (126.3 mmol, 13.16 g, 2.7 eq.) were placed in a 300 mL beaker cell with a temperature-controlled jacket and a magnetic stir bar with a stabilization ring. Ethyl acetate (60 mL) and 1 M aqueous sodium iodide solution (240 mL) were added.Galvanostatic electrolysis was carried out on a bipolar electrode stack consisting of four isostatic graphite plates (each 100 × 50 × 5 mm, immersion depth 7 cm, total active electrode area 105 cm²) at 25 °C and a stirring speed of 750 rpm at 35 mA / cm² until an applied charge of 5.4 F (24488 °C) was reached. The two-phase mixture was transferred to a separatory funnel, the phases were separated, and the aqueous phase was extracted with ethyl acetate (1 × 100 mL). The combined organic phases were dried over magnesium sulfate, filtered, and the solvent removed under reduced pressure. After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 3% EtOAc), the 30-pyrazoline was obtained as a yellow solid (36.0 mmol, 10.6 g, 77%). Example 3: Ethyl 5-(4-(tert-butyl)phenyl)-1-phenyl-4,5-dihydro-1H-pyrazole-3-carboxylate. Synthesis according to method variant A using ethyl 2-(2-phenylhydrazono)acetate (3 mmol, 577 mg, 1 eq.) and 4-tert-butylstyrene (8.1 mmol, 1298 mg, 2.7 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 3% EtOAc), the pyrazoline was obtained as a yellow solid (2.10 mmol, 735 mg, 70%). 1H-NMR (400 MHz, CDCl3), δ / ppm: 7.36 – 7.33 (m, 2H, H-2'''), 7.21 – 7.12 (m, 6H, H-2', H-3', H-3'''), 6.88 (tt, J = 7.1, 1.3 Hz, 1H, H-4'), 5.40 (dd, J = 13.2, 6.9 Hz, 1H, H-5), 4.34 (q, J = 7.1 Hz, 2H, H-2''), 3.70 (dd, , J = 18.0, 13.3 Hz, 1H, (H-4)'), 3.05 (dd, J = 18.0, 6.9 Hz, 1H, (H-4)''), 1.38 (t, J = 7.1 Hz, 3H, H-3''), 1.30 (s, 9H, H-6'''). 1 3 C-NMR (101 MHz, CDCl3), δ / ppm: 162.8, 150.9, 142.7, 138.2, 138.2, 129.0, 126.2, 125.3, 121.2, 114.6, 65.1, 61.2, 42.3, 34.6, 31.4, 14.5. HRMS (APCI+), m / z: calculated for [C 22 H 26 N2O2+ H] +351.2067, found 351.2058. Example 4: Ethyl 5-(naphth-2-yl)-1-phenyl-4,5-dihydro-1H-pyrazole-3-carboxylate Synthesis according to synthetic method variant A using ethyl 2-(2-phenylhydrazono)acetate (3 mmol, 577 mg, 1 eq.) and 2-vinylnaphthalene (8.1 mmol, 1249 mg, 2.7 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 3% EtOAc), pyrazoline 20 was obtained as a yellow solid (1.34 mmol, 462 mg, 45%). 1H-NMR (400 MHz, CDCl3), δ / ppm: 7.87 – 7.75 (m, 3H, H-3''', H-6''', H-7'''), 7.70 (d, J = 1.7 Hz, 1H, H-2'''), 7.51 – 7.45 (m, 2H, H-4''', H-5'''), 7.34 (dd, J = 8.5, 1.8 Hz, 1H, H-8'''), 7.18 – 7.14 (m, 4H, H-2 , H-3 ), 6.88 – 6.84 (m, 1H, H-4 ), 5.58 (dd, J = 13.2, 7.1 Hz, 1H, H-5), 4.35 (q, J = 7.1 Hz, 2H, H-2''), 3.79 (dd, J = 18.0, 13.3 Hz 1H, (H-4)'), 3.12 (dd, J = 18.1, 7.1 Hz 1H, (H-4)''), 1.38 (t, J = 7.1 Hz, 3H, H-3''). 13C-NMR (101 MHz, CDCl3), δ / ppm: 162.8, 142.7, 138.7, 138.3, 133.5, 133.1, 129.7, 129.1, 128.1, 127.9, 126.7, 126.4, 124.7, 123.5, 121.4, 114.7, 65.7, 61.4, 42.4, 14.5. HRMS (ESI+), m / z: calculated for [C 22 H 20 N2O2+ H] + 345.1598, found 345.1598. Example 5: Ethyl 5-(4-methoxyphenyl)-1-phenyl-4,5-dihydro-1H-pyrazole-3-carboxylate Synthesis according to method variant A using ethyl 2-(2-phenylhydrazono)acetate (3 mmol, 577 mg, 1 eq.) and 4-methoxystyrene (8.1 mmol, 1087 mg, 2.7 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 3% EtOAc), the pyrazoline was obtained as a yellow solid (1.34 mmol, 433 mg, 45%). 1H-NMR (400 MHz, CDCl3), δ / ppm: 7.20 – 7.08 (m, 6H, H-2’, H-3’, H-2’’’), 6.90 – 6.82 (m, 3H, H-4’, H-3’’’), 5.37 (dd, J = 13.2, 7.0 Hz, 1H, H-5), 4.34 (q, J = 7.1 Hz, 2H, H-2’’), 3.77 (s, 3H, H-5’’’), 3.69 (dd, J = 13.2, 7.0 Hz, 1H, (H-4)’), 3.02 (dd, J = 18.0, 7.0 Hz, 1H, (H-4)’’), 1.37 (t, J = 7.1 Hz, 3H, H-3’’). 13 C-NMR (101 MHz, CDCl3), δ / ppm: 162.9, 159.3, 142.7, 138.2, 133.4, 129.0, 127.0, 121.3, 114.7, 114.7, 65.0, 61.3, 55.4, 42.4, 14.5. HRMS (ESI+), m / z: berechnet für [C 19 H 20 N2O3+ H] + 325.1547, gefunden 325.1544. Beispiel 6: Ethyl-5-(2,6-dichlorphenyl)-1-phenyl-4,5-dihydro-1H-pyrazol-3-carboxylat Synthesis according to method variant A using ethyl 2-(2-phenylhydrazono)acetate (3 mmol, 577 mg, 1 eq.) and 2,6-dichlorostyrene (8.1 mmol, 1402 mg, 2.7 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 3% EtOAc), the pyrazoline was obtained as a yellow solid (1.77 mmol, 643 mg, 59%). 1H-NMR (400 MHz, CDCl3), δ / ppm: 7.38 (dd, J = 8.0, 1.4 Hz, 1H, H-3'''), 7.24 (dd, J = 8.1, 1.4 Hz, 1H, H-5'''), 7.20 – 7.14 (m, 3H, H-3'', H-4'''), 7.06 – 7.02 (m, 2H, H-2'), 6.87 (dd, J = 7.3, 1.0 Hz, 1H, H-4'), 6.22 (dd, J = 14.6, 10.3 Hz, 1H, H-5), 4.37 (qd, J = 7.1, 3.0 Hz, 2H, H-2''), 3.66 (dd, J = 18.1, 14.6 Hz, 1H, (H-4)'), 3.20 (dd, J = 18.1, 10.3 Hz, 1H, (H-4)''), 1.39 (t, J = 7.1 Hz, 3H, H-3''). 1 3 C-NMR (101 MHz, CDCl3), δ / ppm: 162.8, 142.3, 138.1, 135.1, 135.0, 134.6, 130.9, 129.8, 129.1, 128.6, 121.6, 114.6, 61.3, 61.0, 38.7, 14.5. HRMS (ESI+), m / z: calculated for [C18H16 35 Cl2N2O2 + Na] +385.0481, found 385.0486; calculated for [C18H16 35 Cl 37 ClN2O2 + Na] + 387.0455, found 387.0460; calculated for [C18H16 37 Cl2N2O2 + Na] + 389.0434, found 389.0454. Example 7: Ethyl 1,5,5-triphenyl-4,5-dihydro-1H-pyrazole-3-carboxylate, Synthesis according to method variant A using ethyl 2-(2-phenylhydrazono)acetate (3 mmol, 577 mg, 1 eq.) and 1,1-diphenylethene (8.1 mmol, 1460 mg, 2.7 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 3% EtOAc), the pyrazoline was obtained as a yellow oil (0.87 mmol, 323 mg, 29%). 1 H-NMR (400 MHz, CDCl3), δ / ppm: 7.46 – 7.41 (m, 4H, H-2 ), 7.41 – 7.23 (m, 6H, H-3 , H-4 ), 7.06 – 6.98 (m, 4H, H-2', H-3'), 6.82 – 6.76 (m, 1H, H-4'), 4.34 (q, J = 7.1 Hz, 2H, H-2''), 3.94 (s, 2H, H-4), 1.37 (t, J = 7.1 Hz, 3H, H-3''). 13C NMR (101 MHz, CDCl3), δ / ppm: 162.9, 142.3, 142.2, 137.2, 128.6, 128.3, 128.2, 127.8, 121.5, 117.0, 79.1, 61.3, 56.2, 14.5. HRMS (ESI+), m / z: calculated for [C 24 H 22 N2O2+ H] + 371.1754, found 371.1753. Example 8: Ethyl 1,5-diphenyl-1H-pyrazole-3-carboxylate Synthesis according to synthetic method variant A using ethyl 2-(2-phenylhydrazono)acetate (3.9 mmol, 750 mg, 1 eq.) and phenylacetylene (10.5 mmol, 1070 mg, 2.7 eq.). A charge of 5.4 F was applied. After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 3% EtOAc), the pyrazoline was obtained as a yellow oil (0.99 mmol, 288 mg, 25%). 1 H-NMR (400 MHz, CDCl3), δ / ppm: 7.36 – 7.28 (m, 8H, H-2', H-3', H-2''', H-3'''), 7.23 – 7.20 (m, 2H, H-4', H-4'''), 7.05 (s, 1H, H-4), 4.46 (q, J = 7.1 Hz, 2H, H-2''), 1.43 (t, J = 7.1 Hz, 3H, H-3''). 13C-NMR (101 MHz, CDCl3), δ / ppm: 162.6, 144.8, 144.5, 139.7, 129.7, 129.1, 128.9, 128.8, 128.7, 128.5, 125.9, 110.1, 61.3, 14.6. HRMS (APCI+), m / z: calculated for [C 18 H 16 N2O2+ H] + 293.1285, found 293.1290. Example 9: Ethyl 1-phenyl-1H-pyrazole-3-carboxylate Synthesis according to method variant A using ethyl 2-(2-phenylhydrazono)acetate (3 mmol, 577 mg, 1 eq.) and vinyl acetate (8.1 mmol, 697 mg, 2.7 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 10% EtOAc), the pyrazole was obtained as a yellow solid (0.96 mmol, 208 mg, 32%). In this case, the initially formed acetylated pyrazole spontaneously deacetylated to give ethyl 1-phenyl-1H-pyrazole-3-carboxylate. 1H-NMR (400 MHz, CDCl3), δ / ppm: 7.93 (d, J = 2.5 Hz, 1H, H-5), 7.78 – 7.70 (m, 2H, H-2'), 7.53 – 7.42 (m, 2H, H-3'), 7.40 – 7.30 (m, 1H, H-4'), 6.99 (d, J = 2.5 Hz, 1H, H-4), 4.44 (q, J = 7.1 Hz, 2H, H-2''), 1.42 (t, J = 7.1 Hz, 3H, H-3''). 13 C NMR (101 MHz, CDCl3), δ / ppm: 162.4, 145.4, 139.8, 129.6, 128.5, 127.8, 120.3, 110.5, 61.3, 14.5. HRMS (APCI+), m / z: calculated for [C12H12N2O2 + H] + 217.0972, found 217.0986. Example 10: Ethyl 5-butyl-1-phenyl-1H-pyrazole-3-carboxylate Synthesis according to method variant A using ethyl 2-(2-phenylhydrazono)acetate (3 mmol, 577 mg, 1 eq.) and 1-hexyne (8.1 mmol, 665 mg, 2.7 eq.). Electrolysis was carried out at 50 °C. After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 3% EtOAc), the pyrazoline was obtained as a dark yellow oil (0.26 mmol, 71 mg, 9%). 1H-NMR (400 MHz, CDCl3), δ / ppm: 7.51 – 7.37 (m, 5H, H-2’, H-3’, H-4’), 6.75 (s, 1H, H-4), 4.40 (q, J = 7.1 Hz, 2H, H-2’’), 2.60 (t, J = 7.7 Hz, 2H, H-1’’’), 1.56 (tt, J = 7.6, 7.6 Hz, 2H, H-2’’’), 1.39 (t, J = 7.1 Hz, 3H, H-3’’), 1.30 (qt, J = 7.4, 7.4 Hz, 2H, H-3’’’), 0.85 (t, J = 7.3 Hz, 3H, H-4’’’). 13 C-NMR (101 MHz, CDCl3), δ / ppm: 162.8, 145.8, 144.0, 139.4, 129.2, 128.8, 126.1, 107.9, 61.0, 30.8, 25.9, 22.2, 14.5, 13.8. HRMS (ESI+), m / z: berechnet für [C16H20N2O2 + H] + 273.1598, gefunden 273.1598. Beispiel 11: Ethyl-5-(diethoxyphosphoryl)-1-phenyl-4,5-dihydro-1H-pyrazol-3-carboxylat Synthesis according to synthetic method variant A using ethyl 2-(2-phenylhydrazono)acetate (3 mmol, 577 mg, 1 eq.) and diethyl vinylphosphonate (8.1 mmol, 1330 mg, 2.7 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (5% → 30% EtOAc) and reversed-phase flash column chromatography on C-18 silica with acetonitrile / water (25% → 60% acetonitrile), the pyrazoline was obtained as a yellow oil (1.32 mmol, 469 mg, 44%). 1H-NMR (400 MHz, CDCl3), δ / ppm: 7.44 – 7.36 (m, 2H, H-2'), 7.32 – 7.27 (m, 2H, H-3'), 6.98 (tt, J = 7.3, 1.1 Hz, 1H, H-4'), 4.69 (dd, J = 13.7, 7.2 Hz, 1H, H-5), 4.34 (qd, J = 7.1, 0.7 Hz, 2H, H-2''), 4.19 – 3.95 (m, 4H, H-1'''), 3.67 – 3.39 (m, 2H, H-4), 1.37 (t, J = 7.1 Hz, 3H, H-3''), 1.24 (German, J = 9.8, 7.1 Hz, 6H, H-2'''). 1 3C-NMR (101 MHz, CDCl3), δ / ppm: 162.3, 143.4, 140.3 (d, J = 5.5 Hz), 129.0, 122.2, 115.9, 63.5 (d, J = 7.3 Hz), 63.0 (d, J = 7.0 Hz), 61.5, 58.3 (d, J = 164.0 Hz), 35.4 (d, J = 3.3 Hz), 16.6 (d, J = 5.5 Hz), 16.5 (d, J = 5.5 Hz), 14.5. 3 1 P-NMR (162 MHz, CDCl3), δ / ppm: 19.69. HRMS (ESI+), m / z: calculated for [C 16 H 23 N2O5P + H] + 355.1417, found 355.1421. Example 12: 3-Ethyl-5-methyl-1-phenyl-4,5-dihydro-1H-pyrazole-3,5-dicarboxylate Synthesis according to synthetic method variant A using ethyl 2-(2-phenylhydrazono)acetate (20) (3.9 mmol, 750 mg, 1 eq.) and methyl acrylate (10.5 mmol, 904 mg, 2.7 eq.). A charge of 5.4 F was applied. After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 5% EtOAc), the pyrazoline was obtained as a yellow oil (3.46 mmol, 957 mg, 89%). 1H-NMR (400 MHz, CDCl3), δ / ppm: 7.32 – 7.25 (m, 2H, H-3 ), 7.13 (dt, J = 7.9, 1.1 Hz, 2H, H-2 ), 6.97 (tt, J = 7.3, 1.1 Hz, 1H, H-4’), 4.94 (dd, J = 13.6, 6.6 Hz, 1H, H-5), 4.34 (qd, J = 7.1, 0.7 Hz, 2H, H-2’’), 3.74 (s, 3H, H-2’’’), 3.55 (dd, J = 18.1, 13.5 Hz, 1H, (H-4)’), 3.32 (dd, , J = 18.2, 6.6 Hz, 1H, (H-4)’’), 1.38 (t, J = 7.1 Hz, 3H, H-3’’). 13 C-NMR (101 MHz, CDCl3), δ / ppm: 170.8, 162.2, 142.5, 138.6, 129.4, 121.9, 114.0, 62.3, 61.6, 53.1, 37.4, 14.5. HRMS (APCI+), m / z: berechnet für [C 14 H 16 N2O4+ H] + 277.1183, gefunden 277.1192. Beispiel 13: 3-Ethyl-5,5-dimethyl-1-phenyl-4,5-dihydro-1H-pyrazol-3,5-dicarboxylat Synthesis according to method variant A using ethyl 2-(2-phenylhydrazono)acetate (3 mmol, 577 mg, 1 eq.) and methyl methacrylate (8.1 mmol, 811 mg, 2.7 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 3% EtOAc), the pyrazoline was obtained as a yellow oil (2.44 mmol, 709 mg, 81%). 1 H-NMR (400 MHz, CD2Cl2), δ / ppm: 7.31 – 7.25 (m, 2H, H-3'), 7.10 – 7.06 (m, 2H, H-2'), 6.98 (tt, J = 7.3, 1.1 Hz, 1H, H-4'), 4.30 (q, J = 7.1 Hz, 2H, H-2''), 3.76 (s, 3H, H-2'''), 3.54 (d, J = 17.8 Hz, 1H, (H-4)'), 3.18 (d, J = 17.8 Hz, 1H, (H-4)''), 1.64 (s, 3H, H-1''''), 1.35 (t, J = 7.1 Hz, 3H, H-3''). 13 C-NMR (101 MHz, CD2Cl2), δ / ppm: 173.2, 162.5, 141.9, 137.5, 129.5, 122.3, 115.8, 70.8, 61.5, 53.4, 47.4, 21.6, 14.5. HRMS (ESI+), m / z: calculated for [C 15 H 18 N2O4+ H] + 291.1339, found 291.1344.

[0005] Example 14: 3-Ethyl-5-methyl-5-(2-methoxy-2-oxoethyl)-1-phenyl-4,5-dihydro-1H-pyrazole-3,5-dicarboxylate Synthesis according to method variant A using ethyl 2-(2-phenylhydrazono)acetate (3 mmol, 577 mg, 1 eq.) and dimethyl itaconate (8.1 mmol, 1281 mg, 2.7 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 8% EtOAc), the pyrazoline was obtained as a yellow oil (2.73 mmol, 950 mg, 91%). 1H-NMR (400 MHz, CDCl3), δ / ppm: 7.26 – 7.18 (m, 2H, H-3'), 7.12 – 7.07 (m, 2H, H-2'), 7.01 – 6.95 (m, 1H, H-4'), 4.30 (q, J = 7.1 Hz, 2H, H-2''), 3.72 (d, J = 18.4 Hz 1H (H-1'''')'), 3.70 (s, 3H, H-3''''), 3.65 (d, J = 18.4 Hz, 1H, (H-1'''')''), 3.59 (s, 3H, H-2'''), 3.25 (d, J = 16.6 Hz, 1H, (H-4)'), 2.87 (d, J = 16.6 Hz, 1H, (H-4)''), 1.33 (t, J = 7.1 Hz, 3H, H-3''). 1 3C NMR (101 MHz, CDCl3), δ / ppm: 171.4, 169.7, 162.0, 141.5, 138.9, 129.2, 123.1, 116.9, 71.3, 61.3, 53.3, 51.9, 44.7, 37.8, 14.3. HRMS (ESI+), m / z: calculated for [C17H20N2O6 + H] + 349.1394, found 349.1395. Example 15: Ethyl 5-cyano-1-phenyl-4,5-dihydro-1H-pyrazole-3-carboxylate Synthesis according to synthetic method variant A using ethyl 2-(2-phenylhydrazono)acetate (3 mmol, 577 mg, 1 eq.) and acrylonitrile (8.1 mmol, 430 mg, 2.7 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 3% EtOAc), the pyrazoline was obtained as a yellow solid (2.68 mmol, 653 mg, 90%). 1 H-NMR (400 MHz, CDCl3), δ / ppm: 7.39 – 7.33 (m, 2H, H-3 ), 7.24 (dt, J = 8.8, 1.0 Hz, 2H, H-2 ), 7.10 – 7.04 (m, 1H, H-4'), 5.07 (ddd, J = 10.6, 8.2, 0.6 Hz, 1H, H-5), 4.35 (q, J = 7.1 Hz, 2H, H-2''), 3.61 – 3.50 (m, 2H, H-4), 1.38 (td, J = 7.1, 0.7 Hz, 3H, H-3''). 13C NMR (101 MHz, CDCl3), δ / ppm: 161.3, 141.5, 140.0, 129.6, 123.2, 116.2, 115.0, 61.9, 50.4, 37.9, 14.3. HRMS (ESI+), m / z: calculated for [C 13 H 13 N3O2+ Na] + 266.0900, found 266.0896. Example 16: Ethyl 5-(dimethylcarbamoyl)-1-phenyl-4,5-dihydro-1H-pyrazole-3-carboxylate Synthesis according to method variant A using ethyl 2-(2-phenylhydrazono)acetate (3 mmol, 577 mg, 1 eq.) and N,N-dimethylacrylamide (8.1 mmol, 803 mg, 2.7 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 3% EtOAc), the pyrazoline was obtained as a yellow solid (1.73 mmol, 501 mg, 58%). 1H-NMR (400 MHz, CDCl3), δ / ppm: 7.29 – 7.22 (m, 2H, H-3’), 7.08 – 7.03 (m, 2H, H-2’), 6.96 – 6.90 (m, 1H, H-4’), 5.13 (dd, J = 14.0, 7.9 Hz, 1H, H-5), 4.32 (qd, J = 7.1, 1.7 Hz, 2H, H-2’’), 3.54 (dd, J = 17.8, 14.0 Hz, 1H, (H-4)’), 3.12 (dd, J = 17.9, 7.9 Hz, 1H, (H-4)’’), 3.06 (s, 3H, H-2’’’), 2.97 (s, 3H, H-3’’’), 1.35 (t, J = 7.1 Hz, 3H, H-3’’). 13 C-NMR (101 MHz, CDCl3), δ / ppm: 168.9, 162.3, 142.6, 137.6, 129.3, 121.7, 114.0, 61.9, 61.3, 36.9, 36.9, 36.4, 14.4. HRMS (APCI+), m / z: berechnet für [C 15 H 19 N3O3+ H] + 290.1499, gefunden 290.1491. Beispiel 17: 3-Ethyl-4,5-dimethyl-1-phenyl-4,5-dihydro-1H-pyrazol-3,4,5-tricarboxylat Synthesis according to synthesis method variant A using ethyl 2-(2-phenylhydrazono)acetate (3 mmol, 577 mg, 1 eq.) and dimethyl maleate (8.1 mmol, 1167 mg, 2.7 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 12% EtOAc), the product was obtained as an orange oil (2.00 mmol, 669 mg, 66%) in a 1.9:1 mixture of the 4,5-cis- and 4,5-trans-substituted pyrazoline (determined by 1 H-NMR). Analytical data 3-Ethyl-4,5-dimethyl-4,5-cis-1-phenyl-4,5-dihydro-1H-pyrazole-3,4,5-tricarboxylate: 1H-NMR (400 MHz, CD3CN), δ / ppm: 7.37 – 7.29 (m, 2H, H-3'), 7.06 (dt, J = 7.8, 1.1 Hz, 2H, H-2'), 7.02 (d, J = 7.2, 1.1 Hz, 1H, H-4'), 5.41 (d, J = 13.8 Hz, 1H, H-5), 4.70 (d, J = 13.8 Hz, 1H, H-4), 4.26 (dddd, J = 17.9, 10.8, 7.1, 3.7Hz, 2H, H-2''), 3.71 (s, 3H, H-2''''), 3.66 (s, 3H, H-2'''), 1.29 (t, J = 7.1 Hz, 3H, H-3''). 1 3C NMR (101 MHz, CD3CN), δ / ppm: 169.6, 168.5, 161.9, 143.0, 137.7, 130.3, 123.0, 115.0, 66.2, 62.2, 54.7, 53.6, 14.4. HRMS (ESI+), m / z: calculated for [C16H18N2O6 + H] + 335.1238, found 335.1241. Example 18: 3-Ethyl-4,5-dimethyl-4,5-trans-1-phenyl-4,5-dihydro-1H-pyrazole-3,4,5-tricarboxylate 4' 20 Synthesis according to synthetic method variant A using ethyl 2-(2-phenylhydrazono)acetate (3 mmol, 577 mg, 1 eq.) and dimethyl fumarate (8.1 mmol, 1167 mg, 2.7 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 10% EtOAc), the pyrazoline was obtained as a yellow oil (2.10 mmol, 701 mg, 70%). 1 H-NMR (400 MHz, CDCl3), δ / ppm: 7.33 – 7.28 (m, 2H, H-3'), 7.18 – 7.13 (m, 2H, H-2'), 7.04 – 6.98 (m, 1H, H-4'), 5.17 (d, J = 5.8 Hz, 1H, H-5), 4.39 (d, J = 5.8 Hz, 1H, H-4), 4.44 – 4.25 (m, 2H, H-2''), 3.79 (s, 3H, H-2'''), 3.76 (s, 3H, H-2''''), 1.36 (t, J = 7.1 Hz, 3H, H-3''). 13C-NMR (101 MHz, CDCl3), δ / ppm: 169.1, 169.0, 161.4, 141.8, 135.6, 129.4, 122.5, 114.5, 66.5, 61.7, 54.3, 53.4, 14.4. HRMS (ESI+), m / z: calculated for [C 16 H 18 N2O6+ Na] + 357.1057, found 357.1057. Example 19: Ethyl 3a,8b-cis-1-phenyl-1,3a,4,8b-tetrahydroindeno[1,2-c]pyrazole-3-carboxylate Synthesis according to method variant A using ethyl 2-(2-phenylhydrazono)acetate (3 mmol, 577 mg, 1 eq.) and indene (8.1 mmol, 941 mg, 2.7 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 3% EtOAc), the pyrazoline was obtained as a light yellow solid (1.60 mmol, 491 mg, 52%). 1 H-NMR (400 MHz, CD2Cl2), δ / ppm: 7.45 – 7.35 (m, 5H, H-2', H-3', H-8), 7.32 – 7.23 (m, 2H, H-6, H-7), 7.14 – 7.08 (m, 1H, H-5), 7.02 (tt, J = 7.0, 1.5 Hz, 1H, H-4'), 6.12 (d, J = 10.6 Hz, 1H, H-8b), 4.39 – 4.25 (m, 3H, H-3a, H-2''), 3.53 – 3.41 (m, 2H, H-4), 1.36 (t, J = 7.1 Hz, 3H, H-3''). 13C NMR (101 MHz, CD2Cl2), δ / ppm: 162.9, 143.0, 142.7, 142.0, 140.2, 129.7, 129.2, 127.5, 125.7, 125.4, 121.9, 115.5, 70.1, 61.2, 48.9, 36.4, 14.6. HRMS (ESI+), m / z: calculated for [C19H18N2O2 + H] + 307.1441, found 307.1434. Example 20: Ethyl 4,5-trans-5-(4-methoxyphenyl)-4-methyl-1-phenyl-4,5-dihydro-1H-pyrazole-3-carboxylate Synthesis according to method variant A using ethyl 2-(2-phenylhydrazono)acetate (3 mmol, 577 mg, 1 eq.) and trans-anethole (8.1 mmol, 1200 mg, 2.7 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 5% EtOAc), the pyrazoline was obtained as a yellow oil (0.43 mmol, 165 mg, 16%). 1H-NMR (400 MHz, CDCl3), δ / ppm: 7.22 – 7.16 (m, 2H, H-3'), 7.15 – 7.09 (m, 4H, H-2', H-2''''), 6.90 – 6.81 (m, 3H, H-4', H-3''''), 4.86 (d, J = 5.8 Hz, 1H, H-5), 4.34 (qd, J = 7.1, 2.8 Hz, 2H, H-2''), 3.77 (s, 3H, H-5''''), 3.27 (qd, J = 7.1, 5.7 Hz, 1H, H-4), 1.44 (d, J = 7.1 Hz, 3H, H-1'''), 1.38 (t, J = 7.1 Hz, 3H, H-3''). 1 3 C-NMR (101 MHz, CDCl3), δ / ppm: 162.7, 159.4, 142.6, 142.3, 132.6, 129.0, 126.7, 121.3, 114.7, 73.2, 61.1, 55.4, 50.3, 19.2, 14.4. HRMS (APCI+), m / z: calculated for [C 20 H 22 N2O3+ H] +339.1703, found 339.1695. Example 21: Ethyl 4,5-trans-1,4,5-triphenyl-4,5-dihydro-1H-pyrazole-3-carboxylate (21) Synthesis according to synthetic method variant A using ethyl 2-(2-phenylhydrazono)acetate (3.9 mmol, 750 mg, 1 eq.) and trans-stilbene (10.5 mmol, 1893 mg, 2.7 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 3% EtOAc), the pyrazoline was obtained as an orange solid (0.37 mmol, 137 mg, 9%). 1 H-NMR (400 MHz, CDCl3), δ / ppm: 7.40 – 7.14 (m, 14H, H-2 , H-3 , H-2 , H-3 , H-4 , H-2 , H-3'''', H-4''''), 6.91 (tt, J = 7.0, 1.5 Hz, 1H, H-4'), 5.29 (d, J = 5.2 Hz, 1H, H-5), 4.32 (d, J = 5.2 Hz, 1H, H-4), 4.28 – 4.10 (m, 2H, H-2''), 1.21 (t, J = 7.1 Hz, 3H, H-3''). 13 C-NMR (101 MHz, CDCl3), δ / ppm: 162.3, 142.2, 141.0, 140.7, 140.3, 129.6, 129.3, 129.2, 128.3, 127.8, 127.3, 125.4, 121.6, 114.8, 74.9, 61.1, 61.0, 14.2. HRMS (APCI+), m / z: calculated for [C 24 H 22 N2O2+ H] +371.1754, found 371.1760. Example 22: Ethyl 3a,7a-cis-1-phenyl-3a,4,5,6,7,7a-hexahydro-1H-4,7-methanoindazole-3-carboxylate Synthesis according to synthetic method variant A using ethyl 2-(2-phenylhydrazono)acetate (3.9 mmol, 750 mg, 1 eq.) and norbornene (10.5 mmol, 998 mg, 2.7 eq.). A loading of 5.4 F (2032 C) was applied. After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 3% EtOAc), the pyrazoline was obtained as a yellow solid (3.55 mmol, 1010 mg, 91%). 1 H-NMR (400 MHz, CDCl3), δ / ppm: 7.32 – 7.27 (m, 2H, H-3'), 7.23 – 7.18 (m, 2H, H-2'), 6.93 (tt, J = 7.3, 1.2 Hz, 1H, H-4'), 4.39 – 4.26 (m, 2H, H-2''), 4.23 (d, J = 10.0 Hz, 1H, H-7a), 3.42 (d, J = 9.9 Hz, 1H, H-3a), 2.82 - 2.77 (m, 1H, H-7), 2.71 - 2.66 (m, 1H, H-4), 1.67 - 1.54 (m, 2H, (H-5)', (H-6)'), 1.46 – 1.29 (m, 3H, (H-5)'', (H-6)'', (H-8)'), 1.37 (t, J = 7.1 Hz, 3H, H-3''), 1.27 – 1.18 (m, 1H, (H-8)''). 13C NMR (101 MHz, CDCl3), δ / ppm: 163.1, 142.4, 141.1, 129.2, 121.0, 114.0, 69.2, 61.0, 54.3, 41.6, 40.9, 33.2, 27.7, 24.7, 14.5. HRMS (ESI+), m / z: calculated for [C 17 H 20 N2O2+ H] + 285.1598, found 285.1599. Example 23: Ethyl 3a,9a-cis-5,8-bisacetoxy-1-phenyl-3a,4,9,9a-tetrahydro-1H-4,9-methanobenzo[f]indazole-3-carboxylate 4' O . Synthesis according to method variant A using ethyl 2-(2-phenylhydrazono)acetate (3 mmol, 577 mg, 1 eq.) and 5,8-bisacetoxybenzo[e]norbornene (8.1 mmol, 2092 mg, 2.7 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 5% EtOAc), the pyrazoline was obtained as a yellow solid (2.43 mmol, 1089 mg, 81%). 1H-NMR (400 MHz, CDCl3), δ / ppm: 7.32 (m, 4H, H-2', H-3'), 6.98 (m, 1H, H-4'), 6.89 (d, J = 8.8 Hz, 1H, H-6), 6.86 (d, J = 8.8 Hz, 1H, H-7), 4.80 (d, J = 9.9 Hz, 1H, H-9a), 4.45 – 4.26 (m, 2H, H-2''), 3.88 (d, J = 9.9 Hz, 1H, H-3a), 3.84 (br s, 1H, H-4), 3.83 (br s, 1H, H-9), 2.42 (s, 3H, H-2'''), 2.38 (s, 3H, H-2''''), 1.83 (s, 2H, H-10), 1.41 (t, J = 7.1 Hz, 3H, H-3''). 1 3 C NMR (101 MHz, CDCl3), δ / ppm: 169.6, 169.2, 162.7, 142.8, 142.6, 142.0, 141.0, 138.9, 137.8, 129.3, 121.6, 121.5, 120.8, 114.4, 68.6, 61.1, 54.1, 47.3, 46.2, 43.5, 20.9, 20.9, 14.6. HRMS (APCI+), m / z: calculated for [C25H24N2O6 + H] +449.1707, found 449.1696. Example 24: Ethyl 3a,9a-cis-1-phenyl-3a,4,5,6,7,8,9,9a-octahydro-1H-cycloocta[c]pyrazole-3-carboxylate Synthesis according to method variant A using ethyl 2-(2-phenylhydrazono)acetate (3 mmol, 577 mg, 1 eq.) and cis-cyclooctene (8.1 mmol, 893 mg, 2.7 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 3% EtOAc), the pyrazoline was obtained as a yellow oil (1.02 mmol, 306 mg, 34%). 1H-NMR (400 MHz, CDCl3), δ / ppm: 7.34 – 7.27 (m, 2H, H-3'), 7.16 – 7.11 (m, 2H, H-2'), 6.95 (tt, J = 7.3, 1.1 Hz, 1H, H-4'), 4.44 – 4.25 (m, 3H, H-9a, H-2''), 3.46 (ddd, J = 12.6, 11.0, 1.6 Hz, 1H, H-3a), 2.37 – 2.26 (m, 1H, (H-4)'), 1.92 – 1.40 (m, 11H, (H-4)'', H-5, H-6, H-7, H-8, H-9), 1.37 (t, J = 7.1 Hz, 3H, H-3''). 1 3 C NMR (101 MHz, CDCl3), δ / ppm: 163.2, 142.7, 142.2, 129.1, 121.6, 115.8, 65.6, 61.0, 48.5, 29.3, 27.8, 25.7, 25.5, 24.5, 23.5, 14.5. HRMS (ESI+), m / z: calculated for [C 18 H24 N2O2+ H] + 301.1911, gefunden 301.1910. Beispiel 25: Ethyl-3a,7a-cis-1-phenyl-6,6,7a-trimethyl-3a,4,5,6,7,7a-hexahydro-1H-5,7- methanoindazol-3-carboxylat Synthesis according to synthesis method variant A using ethyl 2-(2-phenylhydrazono)acetate (3 mmol, 577 mg, 1 eq.) and (-)-α-pinene (8.1 mmol, 1103 mg, 2.7 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 3% EtOAc) and purification by preparative HPLC (water (+ 1 vol% formic acid) / acetonitrile 70% → 100% MeCN), the pyrazoline was obtained as a yellow solid (0.11 mmol, 36 mg, 4%). 1H-NMR (400 MHz, CDCl3), δ / ppm: 7.28 – 7.23 (m, 4H, H-2', H-3'), 7.03 – 6.97 (m, 1H, H-4'), 4.42 – 4.27 (m, 2H, H-2''), 3.39 (dd, J = 10.7, 5.0 Hz, 1H, H-3a), 2.57 (dd, J = 6.2, 4.6 Hz, 1H, H-7), 2.46 (dddd, J = 13.8, 10.8, 3.1, 2.1 Hz, 1H, (H-4)'), 2.25 (dddd, J = 10.6, 6.3, 6.3, 2.1Hz, 1H, (H-8)'), 1.96 (dddd, J = 7.8, 3.1, 3.1, 3.0 Hz, 1H, H-5), 1.75 (ddd, J = 13.8, 5.0, 3.0 Hz, 1H, (H-4)''), 1.40 (s, 3H, H-1'''), 1.38 (t, J = 7.1 Hz, 3H, H-3''), 1.32 (s, 3H, H-6''), 1.04 (s, 3H, H-6''), 0.96 (dd, J = 9.4, 4.8 Hz, 1H, (H-8)''). 1 3C-NMR (101 MHz, CDCl3), δ / ppm: 163.4, 142.3, 141.9, 128.9, 122.8, 118.7, 76.3, 60.9, 49.7, 46.3, 25, 38.5, 38.1, 33.4, 28.5, 27.9, 26.1, 23.7, 14.6. HRMS (APCI+), m / z: calculated for [C20H26N2O2 + H] + 327.2067, found 327.2069. Example 26: Ethyl (1R,5S)-6,6-dimethyl-2'-phenyl-1',2'-dihydrospiro[bicyclo[3.1.1]heptane-2,3'-pyrazole]-5'-carboxylate ' Synthesis according to synthesis method variant A using ethyl 2-(2-phenylhydrazono)acetate (3 mmol, 577 mg, 1 eq.) and (-)-^-pinene (8.1 mmol, 1103 mg, 2.7 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 3% EtOAc) and purification by preparative HPLC (water / acetonitrile 70% → 100% MeCN), the pyrazoline was obtained as a yellow solid (0.21 mmol, 68 mg, 7%). 1H-NMR (400 MHz, CDCl3), δ / ppm: 8.41 (s, 1H, H-1’), 7.33 – 7.24 (m, 2H, H-3’’), 7.15 – 7.10 (m, 2H, H-2’’), 6.96 (tt, J = 7.4, 1.2 Hz, 1H, H-4’’), 5.46 – 5.41 (m, 1H, H-4’), 4.31 (q, J = 7.1 Hz, 2H, H-2’’’), 3.50 (dq, J = 16.5, 2.4 Hz, 1H, (H-3)’), 3.27 (dq, J = 16.4, 1.9 Hz, 1H, (H-3)’’), 2.38 (dt, J = 8.8, 5.6 Hz, 1H, (H-7)’), 2.31 (dp, J = 18.0, 3.0 Hz, 1H, (H-4)’), 2.23 (dp, J = 17.9, 2.6 Hz, 1H, (H-4)’’), 2.11 (ttd, J = 5.6, 2.7, 1.2 Hz, 1H, H-5), 2.04 (td, J = 5.6, 1.6 Hz, 1H, H-1), 1.38 (t, J = 7.1 Hz, 3H, 3’’’), 1.27 (s, 3H, H-6’), 1.13 (d, J = 8.8 Hz, 1H, (H-7)’’), 0.86 (s, 3H, H-6’’). 13 C-NMR (101 MHz, CDCl3), δ / ppm: 165.5, 143.3, 142.6, 133.2, 129.4, 122.1, 119.4, 113.9, 61.4, 45.6, 40.7, 38.2, 33.2, 31.8, 31.6, 26.2, 21.1, 14.5. HRMS (APCI+), m / z: berechnet für [C 20 H 26 N2O2+ H] + 327.2067, gefunden 327.2054. Beispiel 27: Ethyl-1-phenyl-5-((trimethylsilyl)methyl)-4,5-dihydro-1H-pyrazol-3-carboxylat . Synthesis according to method variant A using ethyl 2-(2-phenylhydrazono)acetate (3 mmol, 577 mg, 1 eq.) and allyltrimethylsilane (8.1 mmol, 926 mg, 2.7 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 3% EtOAc), the pyrazoline was obtained as a yellow oil (1.03 mmol, 315 mg, 34%). 1H-NMR (400 MHz, CDCl3), δ / ppm: 7.29 (tt, J = 7.3, 2.0 Hz, 2H, H-3'), 7.18 – 7.12 (m, 2H, H-2'), 6.94 (tt, J = 7.3, 1.2 Hz, 1H, H-4'), 4.60 (dddd, J = 11.8, 11.8, 5.2, 1.8 Hz, 1H, H-5), 4.34 (qd, J = 7.1, 2.2 Hz, 2H, H-2''), 3.29 (dd, J = 17.4, 11.7 Hz, 1H, (H-4)'), 2.78 (dd, J = 17.4, 5.1 Hz, 1H, (H-4)''), 1.38 (t, J = 7.1 Hz, 3H H-3''), 1.24 (dd, J = 14.6, 1.8 Hz, 1H, (H-1''')'), 0.90 (dd, J = 14.6, 11.8 Hz, 1H, (H-1''')''), 0.11 (s, 9H, H-2'''). 1 3 C NMR (101 MHz, CDCl3), δ / ppm: 163.4, 141.9, 138.4, 129.3, 121.3, 115.1, 61.2, 58.8, 39.0, 21.2, 14.6, -0.8. HRMS (ESI+), m / z: calculated for [C16H24N2O2Si + H] +305.1680, found 305.1684. Example 28: Ethyl 5-butyl-1-phenyl-4,5-dihydro-1H-pyrazole-3-carboxylate Synthesis according to method variant A using ethyl 2-(2-phenylhydrazono)acetate (3 mmol, 577 mg, 1 eq.) and 1-hexene (8.1 mmol, 682 mg, 2.7 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 3% EtOAc), the pyrazoline was obtained as a yellow oil (0.95 mmol, 261 mg, 32%). 1H-NMR (400 MHz, CDCl3), δ / ppm: 7.32 – 7.27 (m, 2H, H-3'), 7.21 – 7.17 (m, 2H, H-2'), 6.94 (tt, J = 7.3, 1.2 Hz, 1H, H-4'), 4.51 (dddd, J = 12.1, 9.3, 5.2, 2.6 Hz, 1H, H-5), 4.34 (q, J = 7.1 Hz, 2H, H-2''), 3.28 (dd, J = 17.6, 12.2 Hz, 1H, (H-4)'), 2.93 (dd, J = 17.7, 5.2 Hz, 1H, (H-4)''), 1.87 – 1.72 (m, 1H, (H-1''')'), 1.61 – 1.46 (m, 1H, (H-1''')''), 1.38 (t, J = 7.1 Hz, 3H, H-3''), 1.35 – 1.21 (m, 4H, H-2''', H-3'''), 0.99 – 0.79 (m, 3H, H-4'''). 25 13C-NMR (101 MHz, CDCl3), δ / ppm: 163.3, 142.2, 138.5, 129.3, 121.3, 114.8, 61.2, 61.2, 36.8, 31.7, 26.7, 22.6, 14.5, 14.1. HRMS (APCI+), m / z: calculated for [C 16 H 22 N2O2+ H] + 275.1754, found 275.1758. Example 29: Ethyl 5-(4-bromobutyl)-1-phenyl-4,5-dihydro-1H-pyrazole-3-carboxylate Synthesis according to method variant A using ethyl 2-(2-phenylhydrazono)acetate (3 mmol, 577 mg, 1 eq.) and 6-bromo-1-hexene (8.1 mmol, 1321 mg, 2.7 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 3% EtOAc), the pyrazoline was obtained as a yellow oil (0.99 mmol, 348 mg, 33%). 1H-NMR (400 MHz, CDCl3), δ / ppm: 7.33 – 7.27 (m, 2H, H-3'), 7.20 – 7.16 (m, 2H, H-2'), 6.94 (tt, J = 7.3, 1.1 Hz, 1H, H-4'), 4.53 (dddd, J = 11.9, 8.9, 5.2, 2.6 Hz, 1H, H-5), 4.34 (q, J = 7.1 Hz, 2H, H-2''), 3.37 (td, J = 6.7, 2.4 Hz, 2H, H-4'''), 3.30 (dd, J = 17.8, 12.3 Hz, 1H, (H-4)'), 2.94 (dd, J = 17.7, 5.2 Hz, 1H, (H-4)''), 1.89 – 1.72 (m, 3H, (H-1''')', H-3'''), 1.62 – 1.51 (m, 1H, (H-1''')''), 1.46 (dtd, J = 12.1, 9.3, 6.1 Hz, 2H, H-2'''), 1.37 (t, J = 7.1 Hz, 3H, H-3''). 1 3 C-NMR (101 MHz, CDCl3), δ / ppm: 163.1, 142.1, 138.6, 129.3, 121.4, 114.8, 61.2, 60.9, 36.8, 33.3, 32.3, 31.0, 23.2, 14.5. HRMS (ESI+), m / z: calculated for [C16H2179 BrN2O2 + H] + 353.0859, found 353.0864; calculated for [C16H21 81 BrN2O2 + H] + 355.0839, found 355.0845. Example 30: Ethyl 5-cyclohexyl-1-phenyl-4,5-dihydro-1H-pyrazole-3-carboxylate 20 Synthesis according to synthetic method variant A using ethyl 2-(2-phenylhydrazono)acetate (3 mmol, 577 mg, 1 eq.) and vinylcyclohexane (8.1 mmol, 893 mg, 2.7 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 3% EtOAc), the pyrazoline was obtained as an orange solid (0.85 mmol, 254 mg, 28%). 1H-NMR (400 MHz, CDCl3), δ / ppm: 7.34 – 7.24 (m, 2H, H-3'), 7.25 – 7.17 (m, 2H, H-2'), 6.94 (tt, J = 7.2, 1.2 Hz, 1H, H-4'), 4.50 (ddd, J = 12.1, 6.7, 3.5 Hz, 1H, H-5), 4.33 (q, J = 7.1 Hz, 2H, H-2''), 3.10 (dd, J = 18.0, 12.1 Hz, 1H, (H-4)'), 3.05 (dd, J = 18.1, 6.6 Hz, 1H, (H-4)''), 2.01 (m, 1H, H-1'''), 1.83 – 1.75 (m, 1H, (H-3''' b )'), 1.70 – 1.61 (m, 2H, (H-2''' b )'), (H-3''' a)‘), 1.60 – 1.55 (m, 1H, (H-4‘‘‘)‘), 1.37 (t, J = 7.1 Hz, 3H, H-3’’), 1.43 – 1.31 (m, 1H, (H-2‘‘‘ a )‘), 1.30 – 1.18 (m, 1H, (H-3‘‘‘ b )‘‘), 1.15 – 1.00 (m, 3H, (H-2‘‘‘ b )‘‘, (H-3’’’ a )‘‘) (H-4‘‘‘)‘‘), 1.00 – 0.86 (m, 1H, (2’’’ a )‘‘). 1 3 C-NMR (101 MHz, CDCl3), δ / ppm: 163.1, 142.4, 138.7, 129.2, 121.2, 115.1, 65.6, 61.1, 38.3, 32.4, 28.6, 26.4, 26.2, 25.6, 24.7, 14.5. HRMS (ESI+), m / z: berechnet für [C18H24N2O2 + H] + 301.1911, gefunden 301.1906. Beispiel 31: Ethyl-5-(9H-carbazol-9-yl)-1-phenyl-4,5-dihydro-1H-pyrazol-3-carboxylat Synthesis according to method variant A using ethyl 2-(2-phenylhydrazono)acetate (3 mmol, 577 mg, 1 eq.) and N-vinylcarbazole (8.1 mmol, 1565 mg, 2.7 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 3% EtOAc), the pyrazoline was obtained as an orange solid (1.68 mmol, 643 mg, 56%). 1H-NMR (400 MHz, DMSO-d6), δ / ppm: 8.18 (d, J = 7.6 Hz, 1H, H-4'''), 8.15 (d, J = 7.7 Hz, 1H, H-5'''), 8.07 (d, J = 8.3 Hz, 1H, H-1'''), 7.66 – 7.55 (m, 2H, H-5, H-2'''), 7.36 (ddd, J = 8.4, 7.2, 1.3 Hz, 1H, H-7'''), 7.34 – 7.30 (m, 1H, H-3'''), 7.19 (ddd, J = 7.9, 7.3, 0.9 Hz, 1H, H-6'''), 7.12 – 7.03 (m, 2H, H-3'), 7.07 – 6.99 (m, 2H, H-2'), 6.98 (dd, J = 8.3, 0.9 Hz, 1H, H-8'''), 6.78 (dd, J = 7.1, 1.3 Hz, 1H, H-4'), 4.34 (q, J = 7.1 Hz, 2H, H-2''), 3.85 (dd, J = 19.4, 12.9 Hz, 1H, (H-4)'), 3.19 (dd, J = 19.4, 5.9 Hz, 1H, (H-4)''), 1.32 (t, J = 7.1 Hz, 3H, H-3'') 25 13C-NMR (101 MHz, DMSO-d6), δ / ppm: 161.6, 141.2, 139.6, 139.5, 136.4, 129.2, 126.5, 126.4, 123.8, 122.5, 121.7, 120.8, 120.6, 120.2, 120.1, 113.9, 109.8, 109.2, 69.5, 60.9, 37.4, 14.2. HRMS (APCI+), m / z: calculated for [C 24 H 21 N3O2+ H] + 384.1707, found 384.1703. Example 32: 1,3,5-Triphenyl-4,5-dihydro-1H-pyrazole Synthesis according to method variant B using benzaldehyde phenylhydrazone (3.2 mmol, 625 mg, 1 eq.) and styrene (12.5 mmol, 1302 mg, 3.9 eq.). After reversed-phase flash column chromatography on C-18 silica with acetonitrile / water (65% → 72% acetonitrile), the pyrazoline was obtained as a yellow solid (2.36 mmol, 704 mg, 74%). 1H-NMR (400 MHz, CDCl3), δ / ppm: 7.76 – 7.70 (m, 2H, H-2''), 7.42 – 7.37 (m, 2H, H-3''), 7.37 – 7.30 (m, 5H, H-4'', H-2''', H-3'''), 7.30 – 7.24 (m, 1H, H-4'''), 7.23 – 7.16 (m, 2H, H-3'), 7.11 – 7.06 (m, 2H, H-2'), 6.79 (dd, J = 7.2, 1.2 Hz, 1H, H-4'), 5.28 (dd, J = 12.4, 7.3 Hz, 1H, H-5), 3.85 (dd, J = 17.1, 12.4 Hz, 1H, (H-4)'), 3.15 (dd, J = 17.0, 7.3 Hz, 1H, (H-4)''). 1 3 C NMR (101 MHz, CDCl3), δ / ppm: 146.8, 145.0, 142.7, 132.9, 129.3, 129.0, 128.7, 128.7, 127.7, 126.0, 125.9, 119.2, 113.5, 64.6, 43.7. HRMS (ESI+), m / z: calculated for [C21H18N2 + H] +299.1543, found 299.1542. Scale-up (38 mmol): Analogous to synthesis procedure variant B, benzaldehyde phenylhydrazone (38.2 mmol, 7.5 g, 1 eq.) and styrene (149 mmol, 15.52 g, 3.9 eq.) were placed in a 300 mL beaker cell with a temperature-controlled jacket and a magnetic stir bar with a stabilization ring. Tert-butyl methyl ether (60 mL) and 1 MAqueous sodium iodide solution (240 mL) was added. Galvanostatic electrolysis was carried out at 32 mA / cm² on a bipolar electrode stack consisting of four isostatic graphite plates (each 100 × 50 × 5 mm, immersion depth 7 cm, total active electrode area 105 cm²) at 32 °C and a stirring speed of 750 rpm until an applied charge of 2.6 F (9587 °C) was reached. The two-phase mixture was transferred to a separatory funnel, the phases were separated, and the aqueous phase was extracted with ethyl acetate (1 × 100 mL). The combined organic phases were dried over magnesium sulfate, filtered, and the solvent was removed under reduced pressure. Unreacted styrene (8.0 g, 76.8 mmol, 2 eq.) was recovered by vacuum distillation. After recrystallization from isopropanol, the pyrazoline was obtained as a yellow solid (26.4 mmol, 7.89 g, 69%).The sodium iodide used was recovered by freeze-drying the separated aqueous phase (36.3 g, 242 mmol, quant.). An aliquot (3.0 g, 20 mmol) was reused in the synthesis of pyrazoline 1 (see above). Example 33: 3-(4-Methylphenyl)-1,5-diphenyl-4,5-dihydro-1H-pyrazole. Synthesis according to method variant B using 4-methylbenzaldehyde phenylhydrazone (3.2 mmol, 673 mg, 1 eq.) and styrene (12.5 mmol, 1302 mg, 3.9 eq.). After reversed-phase flash column chromatography on C-18 silica with acetonitrile / water (50% → 80% acetonitrile), the pyrazoline was obtained as a yellow solid (2.15 mmol, 672 mg, 67%). 1H-NMR (400 MHz, DMSO-d6), δ / ppm: 7.66 – 7.61 (m, 2H, H-2’’), 7.36 – 7.31 (m, 2H, H-3’’’), 7.30 – 7.21 (m, 5H, H-3’’, H-2’’’, H-4’’’), 7.17 – 7.11 (m, 2H, H-3’), 7.01 – 6.96 (m, 2H, H-2’), 6.70 (tt, J = 7.2, 1.1 Hz, 1H, H-4’), 5.44 (dd, J = 12.2, 6.4 Hz, 1H, H-5), 3.89 (dd, J = 17.4, 12.2 Hz, 1H, (H-4)’), 3.07 (dd, J = 17.4, 6.4 Hz, 1H, (H-4)’’), 2.33 (s, 3H, H-5’’). 13 C-NMR (101 MHz, DMSO-d6), δ / ppm: 147.3, 144.4, 142.6, 138.3, 129.5, 129.2, 129.0, 128.8, 127.4, 125.8, 125.7, 118.4, 112.9, 63.1, 43.1, 21.0. HRMS (ESI+), m / z: berechnet für [C22H20N2+ H] + 313.1699, gefunden 313.1701.

[0006] Beispiel 34: 3-(4-tert.-Butylphenyl)-1,5-diphenyl-4,5-dihydro-1H-pyrazol 4' Synthesis according to method variant B using 4-tert-butylbenzaldehyde phenylhydrazone (3.2 mmol, 808 mg, 1 eq.) and styrene (12.5 mmol, 1302 mg, 3.9 eq.). After reversed-phase flash column chromatography on C-18 silica with acetonitrile / water (75% → 85% acetonitrile), the pyrazoline was obtained as a yellow solid (0.80 mmol, 285 mg, 25%). 1H-NMR (400 MHz, CDCl3), δ / ppm: 7.63 – 7.59 (m, 2H, H-2''), 7.38 – 7.33 (m, 2H, H-3''), 7.31 – 7.22 (m, 4H, H-2''', H-3'''), 7.20 (td, J = 5.3, 3.0 Hz, 1H, H-4'''), 7.12 (dt, J = 7.3, 2.1 Hz, 2H, H-3'), 7.05 – 6.98 (m, 2H, H-2'), 6.71 (dt, J = 7.3, 1.2 Hz, 1H, H-4'), 5.20 (dd, J = 12.3, 7.1 Hz, 1H, H-5), 3.78 (dd, J = 17.0, 12.3 Hz, 1H, (H-4)'), 3.08 (dd, J = 17.0, 7.1 Hz, 1H, (H-4)''), 1.28 (s, 9H, H-6''). 1 3 C-NMR (101 MHz, CDCl3), δ / ppm: 152.0, 146.9, 145.1, 142.8, 130.1, 129.2, 129.0, 127.6, 126.0, 125.7, 125.6, 119.0, 113.4, 64.5, 43.8, 34.9, 31.4. HRMS (ESI+), m / z: calculated for [C 25 H 26 N2+ H]+ 355.2169, found 355.2175. Example 35: 3-(4-Phenylphenyl)-1,5-diphenyl-4,5-dihydro-1H-pyrazole Synthesis according to method variant B using 4-phenylbenzaldehyde phenylhydrazone (3.2 mmol, 872 mg, 1 eq.) and styrene (12.5 mmol, 1302 mg, 3.9 eq.). After reversed-phase flash column chromatography on C-18 silica with acetonitrile / water (70% → 100% acetonitrile), the pyrazoline was obtained as a dark yellow solid (0.65 mmol, 244 mg, 20%). 1 H-NMR (400 MHz, DMSO-d6), δ / ppm: 7.86 – 7.81 (m, 2H, H-2 ), 7.76 – 7.70 (m, 4H, H-3 , H-6 ), 7.53 – 7.21 (m, 8H, H-7'', H-8'', H-2''', H-3''', H-4'''), 7.20 - 7.12 (m, 2H, H-3'), 7.08 - 6.97 (m, 2H, H-2'), 6.72 (dd, J = 7.3, 1.2 Hz, 1H, H-4'), 5.51 (dd, J = 12.2, 6.3 Hz, 1H, H-5), 3.96 (dd, J = 17.5, 12.2 Hz, 1H, (H-4)'), 3.15 (dd, J = 17.5, 6.3 Hz, 1H, (H-4)''). 13C NMR (101 MHz, DMSO-d6), δ / ppm: 146.9, 144.1, 142.6, 140.1, 131.4, 129.0, 128.9, 128.5, 127.4, 126.8, 126.5, 126.3, 125.9, 125.3, 118.7, 113.0, 63.2, 43.0. HRMS (ESI+), m / z: calculated for [C 27 H 22 N2+ H] + 375.1856, found 375.1848. Example 36: 3-(Naphth-2-yl)-1,5-diphenyl-4,5-dihydro-1H-pyrazole Synthesis according to method variant B using 2-formylnaphthalenephenylhydrazone (3.2 mmol, 788 mg, 1 eq.) and styrene (12.5 mmol, 1302 mg, 3.9 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 3% EtOAc), the pyrazoline was obtained as a yellow solid (0.79 mmol, 275 mg, 25%). 1H-NMR (400 MHz, CDCl3), δ / ppm: 8.18 (dd, J = 8.6, 1.7 Hz, 1H, H-8’’), 7.88 – 7.77 (m, 4H, H-2’’, H-3’’, H-6’’, H-7’’), 7.50 – 7.45 (m, 2H, H-4’’, H-5’’), 7.37 – 7.32 (m, 4H, H-2’’’, H-3’’’), 7.30 – 7.24 (m, 1H, H-4’’’), 7.24 – 7.17 (m, 2H, H-3’), 7.15 – 7.10 (m, 2H, H-2’), 6.80 (tt, J = 7.2, 1.2 Hz, 1H, H-4’), 5.34 (dd, J = 12.4, 7.2 Hz, 1H, H-5), 3.97 (dd, J = 16.9, 12.4 Hz, 1H, (H-4)’), 3.28 (dd, J = 16.9, 7.2 Hz, 1H, (H-4)’’). 13 C-NMR (101 MHz, CDCl3), δ / ppm: 146.9, 144.9, 142.7, 133.6, 133.5, 130.6, 129.3, 129.1, 128.3, 128.2, 128.0, 127.7, 126.6, 126.5, 126.0, 125.2, 123.6, 119.3, 113.6, 64.7, 43.7. HRMS (ESI+), m / z: berechnet für [C25H20N2+ H] + 349.1699, gefunden 349.1707. Beispiel 37: 3-(4-Fluorphenyl)-1,5-diphenyl-4,5-dihydro-1H-pyrazol Synthesis according to method variant B using 4-fluorobenzaldehyde phenylhydrazone (3.2 mmol, 686 mg, 1 eq.) and styrene (12.5 mmol, 1302 mg, 3.9 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 2% EtOAc), the pyrazoline was obtained as an orange solid (2.44 mmol, 772 mg, 76%). 1H-NMR (400 MHz, CD2Cl2), δ / ppm: 7.77 – 7.67 (m, 2H, H-2''), 7.39 – 7.24 (m, 5H, H-2''', H-3''', H-4'''), 7.19 – 7.14 (m, 2H, H-3''), 7.13 – 7.07 (m, 2H, H-3''), 7.07 – 7.02 (m, 2H, H-2'), 6.76 (dd, J = 7.3, 1.2 Hz, 1H, H-4'), 5.31 (dd, J = 12.3, 7.3 Hz, 1H, H-5), 3.85 (dd, J = 17.1, 12.3Hz, 1H, (H-4)'), 3.12 (dd, J = 17.1, 7.1 Hz, 1H, (H-4)''). 1 3 C-NMR (101 MHz, CD2Cl2), δ / ppm: 164.6, 162.1, 146.4, 145.2, 143.0, 129.5, 129.2, 128.0, 127.9, 127.8, 126.3, 119.4, 116.0, 115.8, 113.6, 64.8, 44.0. 1 9 F NMR (376 MHz, CD3CN), δ / ppm: -115.4. HRMS (APCI+), m / z: calculated for [C21H17FN2 + H] +317.1449, found 317.1446. Example 38: 3-(4-Chlorophenyl)-1,5-diphenyl-4,5-dihydro-1H-pyrazole Synthesis according to synthetic method variant B using 4-chlorobenzaldehyde phenylhydrazone (3.2 mmol, 738 mg, 1 eq.) and styrene (12.5 mmol, 1302 mg, 3.9 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 3% EtOAc), the pyrazoline was obtained as a colorless solid 20 (2.25 mmol, 749 mg, 70%). 1 H-NMR (400 MHz, (CD3)2CO), δ / ppm: 7.82 – 7.74 (m, 2H, H-2 ), 7.47 – 7.37 (m, 2H, H-3 ), 7.39 – 7.29 (m, 4H, H-2''', H-3'''), 7.32 – 7.20 (m, 1H, H-4'''), 7.19 – 7.09 (m, 2H, H-3'), 7.10 – 7.03 (m, 2H, H-2'), 6.73 (dd, J = 7.2, 1.3 Hz, 1H, H-4'), 5.47 (dd, J = 12.4, 6.8 Hz, 1H, H-5), 3.96 (dd, J = 17.4, 12.4 Hz, 1H, (H-4)'), 3.13 (dd, J = 17.4, 6.8 Hz, 1H, (H-4)''). 13C-NMR (101 MHz, (CD3)2CO), δ / ppm: 206.3, 146.8, 145.5, 143.7, 134.5, 132.7, 129.9, 129.6, 129.5, 128.4, 128.1, 126.8, 119.8, 114.2, 65.0, 43.9. HRMS (ESI+), m / z: calculated for [C 21 H 17 35 ClN2+ H] + 333.1153, found 333.1151; calculated for [C 21 H 17 37 ClN2+ H] + 335.1131, found 335.1133. Example 39: 3-(4-Bromophenyl)-1,5-diphenyl-4,5-dihydro-1H-pyrazole Synthesis according to method variant B using 4-bromobenzaldehyde phenylhydrazone (3.2 mmol, 880 mg, 1 eq.) and styrene (12.5 mmol, 1302 mg, 3.9 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 2% EtOAc), the pyrazoline was obtained as a yellow solid (1.95 mmol, 737 mg, 61%). 1H-NMR (400 MHz, DMSO-d6), δ / ppm: 7.73 – 7.64 (m, 2H, H-2''), 7.64 – 7.58 (m, 2H, H-3''), 7.38 – 7.21 (m, 5H, H-2''', H-3''', H-4'''), 7.19 – 7.10 (m, 2H, H-3'), 7.07 – 6.96 (m, 2H, H-2'), 6.72 (dd, J = 7.3, 1.1 Hz, 1H, H-4'), 5.50 (dd, J = 12.3, 6.4 Hz, 1H, H-5), 3.91 (dd, J = 17.5, 12.4Hz, 1H, (H-4)'), 3.10 (dd, J = 17.5, 6.4 Hz, 1H, (H-4)''). 13 C-NMR (101 MHz, DMSO-d6), δ / ppm: 146.2, 144.0, 142.4, 131.6, 131.5, 129.0, 128.9, 127.6, 127.5, 125.8, 121.7, 118.8, 113.0, 63.3, 42.7. HRMS (ESI+), m / z: calculated for [C21H17 79 BrN2 + H] + 377.0648, found 377.0650; calculated for [C21H17 81 BrN2 + H] + 379.0630, found 379.0632. Example 40: 3-(2,6-Dichlorophenyl)-1,5-diphenyl-4,5-dihydro-1H-pyrazole Synthesis according to method variant B using 2,6-dichlorobenzaldehyde phenylhydrazone (3.2 mmol, 848 mg, 1 eq.) and styrene (12.5 mmol, 1302 mg, 3.9 eq.). After reversed-phase flash column chromatography on C-18 silica with acetonitrile / water (50% → 80% acetonitrile), the pyrazoline was obtained as a yellow oil (2.60 mmol, 955 mg, 81%). 1H-NMR (400 MHz, DMSO-d6), δ / ppm: 7.60 – 7.56 (m, 2H, H-3''), 7.48 (dd, J = 8.9, 7.2 Hz, 1H, H-4''), 7.42 – 7.33 (m, 4H, H-2''', H-3'''), 7.30 - 7.24 (m, 1H, H-4'''), 7.17 - 7.08 (m, 2H, H-3'), 6.96 - 6.89 (m, 2H, H-2'), 6.72 (dd, J = 7.2, 1.1 Hz, 1H, H-4'), 5.53 (dd, J = 12.4, 6.8 Hz, 1H, H-5), 3.85 (dd, J = 17.9, 12.4 Hz, 1H, (H-4)'), 2.97 (dd, J = 17.9, 6.9 Hz, 1H, (H-4)''). 1 3 C-NMR (101 MHz, DMSO-d6), δ / ppm: 144.4, 144.3, 142.3, 134.5, 131.5, 131.1, 128.9, 128.9, 128.5, 127.5, 126.1, 119.0, 113.0, 63.3, 45.9. HRMS (ESI+), m / z: calculated for [C 21 H 16 35 Cl2N2+ H] +367.0763, found 367.0758; calculated for [C 21 H 16 35 Cl 37 ClN2+ H] + 369.0738, found 369.0735; calculated for [C 21 H 16 37 Cl2N2+ H] + 371.0718, found 371.0725. Example 41: 1,5-Diphenyl-3-(4-(trifluoromethyl)phenyl)-4,5-dihydro-1H-pyrazole Synthesis according to method variant B using 4-20 trifluoromethylbenzaldehyde phenylhydrazone (3.2 mmol, 846 mg, 1 eq.) and styrene (12.5 mmol, 1302 mg, 3.9 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 2% EtOAc), the pyrazoline was obtained as a yellow solid (1.21 mmol, 445 mg, 38%). 1H-NMR (400 MHz, CD2Cl2), δ / ppm: 7.88 – 7.79 (m, 2H, H-2 ), 7.68 – 7.62 (m, 2H, H-3 ), 7.39 – 7.25 (m, 5H, H-2’’’, H-3’’’, H-4’’’), 7.22 – 7.14 (m, 2H, H-3’), 7.11 – 7.05 (m, 2H, H-2’), 6.80 (tt, J = 7.2, 1.2 Hz, 1H, H-4’), 5.39 (dd, J = 12.5, 6.9 Hz, 1H, H-5), 3.88 (dd, J = 17.2, 12.5 Hz, 1H, (H-4)’), 3.16 (dd, J = 17.2, 7.0 Hz, 1H, (H-4)’’). 13 C-NMR (101 MHz, CD2Cl2), δ / ppm: 145.6, 144.6, 142.7, 136.8, 123.0 (q, J = 32.5 Hz), 129.5, 129.3, 128.8, 126.3, 126.1, 125.8 (q, J = 3.9 Hz), 124.7 (q, J = 271.9 Hz), 119.9, 113.9, 64.9, 43.5. 19 F-NMR (376 MHz, CD2Cl2), δ / ppm: -64.0. HRMS (APCI+), m / z: berechnet für [C 22 H 17 F3N2+ H] + 367.1417, gefunden 367.1411. Beispiel 42: 3-(4-Cyanophenyl)-1,5-diphenyl-4,5-dihydro-1H-pyrazol Synthesis according to method variant B using 4-cyanobenzaldehyde phenylhydrazone (3.2 mmol, 708 mg, 1 eq.) and styrene (12.5 mmol, 1302 mg, 3.9 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 2% EtOAc), the pyrazoline was obtained as a bright yellow solid (1.79 mmol, 579 mg, 56%). 1 H-NMR (400 MHz, DMSO-d6), δ / ppm: 7.89 (d, J = 8.6 Hz, 2H, H-2''), 7.85 (d, J = 8.6 Hz, 2H, H-3''), 7.34 (dd, J = 8.0, 6.8 Hz, 2H, H-3'''), 7.32 – 7.21 (m, 3H, H-2''', H-4'''), 7.22 – 7.13 (m, 2H, H-3'), 7.09 – 7.01 (m, 2H, H-2'), 6.81 – 6.72 (m, 1H, H-4'), 5.60 (dd, J = 12.5, 6.3 Hz, 1H, H-5), 3.93 (dd, J = 17.6, 12.5 Hz, 1H, (H-4)'), 3.15 (dd, J = 17.6, 6.3 Hz, 1H, (H-4)''). 13 C NMR (101 MHz, DMSO-d6), δ / ppm: 145.4, 143.4, 142.1, 136.7, 132.5, 129.1, 129.0, 127.6, 126.1, 125.8, 119.4, 118.9, 113.3, 110.1, 63.5, 42.3. HRMS (APCI+), m / z: calculated for [C22H17N3 + H] +324.1495, found 324.1487. Example 43: Methyl 4-(1,5-diphenyl-4,5-dihydro-1H-pyrazol-3-yl)benzoate Synthesis according to method variant B using 4-formylbenzoic acid methyl ester phenylhydrazone (3.2 mmol, 814 mg, 1 eq.) and styrene (12.5 mmol, 1302 mg, 3.9 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 3% EtOAc), the pyrazoline was obtained as a bright yellow solid (2.32 mmol, 826 mg, 72%). 1H-NMR (400 MHz, DMSO-d6), δ / ppm: 8.02 – 7.95 (m, 2H, H-3''), 7.89 – 7.83 (m, 2H, H-2''), 7.39 – 7.31 (m, 2H, H-3'''), 7.31 – 7.21 (m, 3H, H-2''', H-4'''), 7.21 – 7.14 (m, 2H, H-3'), 7.08 – 7.01 (m, 2H, H-2'), 6.75 (dd, J = 7.1, 1.2 Hz, 1H, H-4'), 5.58 (dd, J = 12.4, 6.2 Hz, 1H, H-5), 3.95 (dd, J = 17.5, 12.5 Hz, 1H, (H-4)'), 3.86 (s, 3H, H-6''), 3.15 (dd, J = 17.5, 6.3 Hz, 1H, (H-4)''). 1 3C-NMR (101 MHz, DMSO-d6), δ / ppm: 165.9, 146.0, 143.6, 142.2, 136.7, 129.5, 129.1, 128.9, 128.9, 127.5, 125.8, 125.7, 119.2, 113.2, 63.3, 52.2, 42.6. HRMS (APCI+), m / z: calculated for [C 23 H 20 N2O2+ H] + 357.1598, found 357.1597. Example 44: 3-(4-Nitrophenyl)-1,5-diphenyl-4,5-dihydro-1H-pyrazole Synthesis according to method variant B using 4-nitrobenzaldehyde phenylhydrazone (3.2 mmol, 772 mg, 1 eq.) and styrene (12.5 mmol, 1302 mg, 3.9 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 5% EtOAc), the pyrazoline was obtained as a red solid 20 (1.70 mmol, 588 mg, 53%). Recrystallization from methanol gave red needles. 1H-NMR (400 MHz, DMSO-d6), δ / ppm: 8.29 – 8.23 (m, 2H, H-3 ), 7.99 – 7.93 (m, 2H, H-2 ), 7.35 (dd, J = 8.0, 6.8 Hz, 2H, H-3’’’), 7.31 – 7.23 (m, 3H, H-2’’’, H-4’’’), 7.22 – 7.16 (m, 2H, H-3’), 7.11 – 7.05 (m, 2H, H-2’), 6.78 (tt, J = 7.2, 1.2 Hz, 1H, H-4’), 5.65 (dd, J = 12.6, 6.2 Hz, 1H, H-5), 3.97 (dd, J = 17.6, 12.6 Hz, 1H, (H-4)’), 3.19 (dd, J = 17.6, 6.2 Hz, 1H, (H-4)’’). 13 C-NMR (101 MHz, DMSO-d6), δ / ppm: 146.5, 145.1, 143.2, 142.0, 138.7, 129.1, 129.0, 127.6, 126.3, 125.8, 124.0, 119.7, 113.4, 63.6, 42.3. HRMS (APCI+), m / z: berechnet für [C 21 H 17 N3O2+ H] + 344.1394, gefunden 344.1388. Beispiel 45: 2-Phenyl-2,3,3a,4-tetrahydrochromeno[4,3-c]pyrazol (45) 3' 4' Synthesis according to method variant B using 2-allyloxybenzaldehyde phenylhydrazone (3.2 mmol, 807 mg, 1 eq.) and styrene (12.5 mmol, 1302 mg, 3.9 eq.). After reversed-phase flash column chromatography on C-18 silica with acetonitrile / water (50% → 80% acetonitrile), the pyrazoline was obtained as an orange oil (1.79 mmol, 447 mg, 56%). 1 H-NMR (400 MHz, CD3CN), δ / ppm: 7.78 (dd, J = 7.7, 1.7 Hz, 1H, H-9), 7.32 – 7.24 (m, 3H, H-7, H-3'), 7.14 – 7.09 (m, 2H, H-2'), 7.00 (td, J = 7.5, 1.1 Hz, 1H, H-8), 6.93 (dd, J = 8.3, 1.1 Hz, 1H, H-3), 6.85 (dd, J = 7.3, 1.2 Hz, 1H, H-4'), 4.72 (dd, J = 10.3, 5.8 Hz, 1H, (H-4)'), 4.24 (dd, J = 10.6, 9.7 Hz, 1H, (H-3)'), 4.11 (dd, J = 12.3, 10.3 Hz, 1H, (H-4)''), 3.81 (dddd, J = 13.3, 12.4, 10.6, 5.8 Hz, 1H, H-3a), 3.28 (dd, J = 13.2, 9.7 Hz, 1H, (H-3)'). 13C-NMR (101 MHz, CD3CN), δ / ppm: 156.9, 147.8, 147.7, 131.8, 130.1, 125.0, 122.5, 120.3, 118.3, 118.2, 117.6, 114.2, 70.5, 52.3, 43.2. HRMS (APCI+), m / z: calculated for [C 16 H 14 N2O + H] + 251.1179, found 251.1178. Example 46: 3-Methyl-1,5-diphenyl-4,5-dihydro-1H-pyrazole Synthesis according to method variant A using acetaldehyde phenylhydrazone (3 mmol, 403 mg, 1 eq.) and styrene (8.1 mmol, 844 mg, 2.7 eq.). Electrolysis under an argon atmosphere. After reversed-phase flash column chromatography on C-18 silica with acetonitrile / water (50% → 60% acetonitrile), the pyrazoline was obtained as a dark red solid (1.15 mmol, 273 mg, 38%). 1H-NMR (400 MHz, CD3CN), δ / ppm: 7.33 (tt, J = 6.8, 1.0 Hz, 2H, H-3'''), 7.29 – 7.20 (m, 3H, H-2''', H-4'''), 7.11 – 7.04 (m, 2H, H-3''), 6.86 – 6.79 (m, 2H, H-2'), 6.63 (dd, J = 7.2, 1.1 Hz, 1H, H-4'), 5.11 (dd, J = 11.9, 7.3 Hz, 1H, H-5), 3.48 (ddd, J = 17.7, 11.9, 1.3 Hz, 1H, (H-4)'), 2.63 (ddd, J = 17.6, 7.3, 1.2 Hz, 1H, (H-4)''), 2.00 (dd, J = 1.2, 1.1 Hz, 3H, H-1''). 1 3 C NMR (101 MHz, CD3CN), δ / ppm: 149.1, 145.6, 143.1, 128.9, 128.7, 127.2, 125.9, 117.8, 112.5, 63.3, 47.3, 15.5. HRMS (ESI+), m / z: calculated for [C 16 H 16 N2+ H] +237.1386, found 237.1388. Examples 47 and 48: 3-Cyclopropyl-1,5-diphenyl-4,5-dihydro-1H-pyrazole (47) and 3-Cyclopropyl-1,5-diphenyl-1H-pyrazole (48) Synthesis according to synthesis method variant A using formylcyclopropanephenylhydrazone (3 mmol, 479 mg, 1 eq.) and styrene (8.1 mmol, 844 mg, 2.7 eq.). A loading of 2 F 20 (579 °C) was applied. After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 3% EtOAc) and purification by preparative HPLC (water (+ 1 vol% formic acid) / acetonitrile 70% → 100% MeCN), pyrazoline 47 was obtained as an orange oil (0.69 mmol, 180 mg, 23%). Pyrazole 48 was obtained as a yellow oil (0.23 mmol, 61 mg, 8%) as a byproduct. Analytical data 3-Cyclopropyl-1,5-diphenyl-4,5-dihydro-1H-pyrazole 47: 1H-NMR (400 MHz, CDCl3), δ / ppm: 7.36 – 7.29 (m, 2H, H-3’’’), 7.28 – 7.21 (m, 3H, H-2’’’, H-4’’’), 7.12 – 7.06 (m, 2H, H-3’), 6.89 – 6.84 (m, 2H, H-2’), 6.66 (tt, J = 7.3, 1.1 Hz, 1H, H-4’), 5.06 (dd, J = 11.7, 7.3 Hz, 1H, H-5), 3.31 (ddd, J = 17.4, 11.7, 0.6 Hz, 1H, (H-4)’), 2.51 (dd, J = 17.3, 7.3 Hz, 1H, (H-4)’’), 1.82 (tt, J = 8.4, 5.1 Hz, 1H, H-1’’), 0.86 – 0.81 (m, 2H, (H-2’’)’), 0.81 – 0.68 (m, 2H, (H-2’’)’). 13 C-NMR (101 MHz, CDCl3), δ / ppm: 155.0, 146.9, 144.1, 129.9, 129.7, 128.3, 126.9, 119.0, 118.3, 113.8, 64.6, 44.4, 12.0, 6.3, 6.1. HRMS (APCI+), m / z: berechnet für [C 18 H 18 N2+ H] + 263.1543, gefunden 263.1540. Analytische Daten 3-Cyclopropyl-1,5-diphenyl-1H-pyrazol 48: 1 H-NMR (400 MHz, CD3CN), δ / ppm: 7.31 – 7.20 (m, 6H, H-3’, H-4’, H-3’’’, H-4’’’), 7.19 – 7.11 (m, 4H, H-2’, H-2’’’), 6.20 (d, J = 1.3 Hz, 1H, H-4), 1.96 – 1.86 (m, 1H, H-1’’), 0.93 – 0.85 (m, 2H, (H-2’’)’), 0.76 – 0.68 (m, 2H, (H-2’’)’’). 13C NMR (101 MHz, CD3CN), δ / ppm: 156.6, 144.5, 141.3, 131.8, 129.8, 129.6, 129.4, 129.1, 128.1, 126.1, 118.3, 105.3, 9.8, 8.6. HRMS (APCI+), m / z: calculated for [C18H16N2 + H] + 261.1386, found 261.1387. Examples 49 and 50: 3-((1R,5S)-6,6-Dimethylbicyclo[3.1.1]hept-2-en-2-yl)-1,5-diphenyl-4,5-dihydro-1H-pyrazole (49) and (4R,6R)-5,5-Dimethyl-1-phenyl-4,5,6,7-tetrahydro-1H-4,6-methanoindazole (50) Synthesis according to method variant B using 2-allyloxybenzaldehyde phenylhydrazone (3.2 mmol, 769 mg, 1 eq.) and styrene (12.5 mmol, 1302 mg, 3.9 eq.). Electrolysis at 25 °C. After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 2% EtOAc), pyrazoline 49 was obtained as an orange solid (0.77 mmol, 264 mg, 24%). Pyrazoline 50 was obtained as a dark yellow solid (0.54 mmol, 129 mg, 17%) as a byproduct. Analytical data 3-((1R,5S)-6,6-Dimethylbicyclo[3.1.1]hept-2-en-2-yl)-1,5-diphenyl-4,5-dihydro- 1H-pyrazole 49:1 H-NMR (400 MHz, CDCl3), δ / ppm: 7.36 – 7.21 (m, 5H, H-2’’’, H-3’’’, H-4’’’), 7.14 (ddd, J = 9.2, 7.2, 2.0 Hz, 2H, H-3’), 7.01 – 6.95 (m, 2H, H-2’), 6.74 (tt, J = 7.2, 1.2 Hz, 1H, H-4’), 5.65 (qt, J = 3.5, 1.4 Hz, 1H, H-2’’), 5.12 (ddd, J = 12.1, 7.8 Hz, 1H, H-5), 3.61 (ddd, J = 16.5, 12.2, 3.9 Hz, 1H, (H-4)’), 3.20 (qd, J = 6.0, 1.5 Hz, 1H, H-4’’), 2.90 (ddd, J = 16.7, 7.4, 4.8 Hz, 1H, (H-4)’’), 2.52 (dtd, J = 8.6, 5.7, 2.8 Hz, 1H, (H-3’’)’), 2.44 (ddd, J = 19.1, 3.3, 2.4 Hz, 1H, (H-7’’)’), 2.38 (dt, J = 19.2, 3.1 Hz, 1H, (H-7’’)’’), 2.16 (dddt, J = 5.8, 4.3, 2.9, 1.5 Hz, 1H, H-6’’), 1.40 (d, J = 4.3 Hz, 3H, H-5’’’), 1.22 (dd, J = 8.9, 7.6 Hz, 1H, (H-3’’)’’), 0.85 (d, J = 4.1 Hz, 3H, H-5’’’’). Inseparable mixture of 5R / S- diastereomers. 13C-NMR (101 MHz, CDCl3), δ / ppm: 148.4, 145.2, 143.0, 142.3, 129.2, 128.9, 127.5, 126.0, 124.7, 118.8, 113.4, 64.5, 42.9, 42.0, 40.8, 37.9, 32.4, 31.5, 26.4, 21.1. Inseparable mixture of 5R / S- diastereomers. HRMS (APCI+), m / z: berechnet für [C24H26N2 + H] + 343.2169, gefunden 343.2155. Analytische Daten (4R,6R)-5,5-dimethyl-1-phenyl-4,5,6,7-tetrahydro-1H-4,6-methanoindazol 50: 1 H-NMR (400 MHz, CDCl3), δ / ppm: 7.62 – 7.56 (m, 2H, H-2’), 7.40 – 7.33 (m, 2H, H-3’), 7.32 (d, J = 0.6 Hz, 1H, H-4), 7.20 (tq, J = 7.7, 1.0 Hz, 1H, H-4’), 3.03 (dd, J = 16.4, 3.1 Hz, 1H, (H-8)’), 2.92 (dd, J = 16.4, 2.7 Hz, 1H, (H-8)’’), 2.70 (t, J = 5.4 Hz, 1H, H-4), 2.62 (dt, J = 9.3, 5.7 Hz, 1H, (H-7)’), 2.28 (tt, J = 5.8, 2.9 Hz, 1H, H-6), 1.33 (s, 3H, H-5’), 1.29 (d, J = 9.3 Hz, 1H, (H-7)’’), 0.62 (s, 3H, H-5’’). 13C NMR (101 MHz, CDCl3), δ / ppm: 140.6, 136.4, 136.3, 129.2, 129.0, 126.2, 121.1, 41.4, 41.3, 39.3, 33.8, 29.1, 26.4, 21.3. HRMS (APCI+), m / z: calculated for [C16H18N2 + H] + 239.1543, found 239.1545. Example 51: Ethyl 1-(4-methylphenyl)-5-phenyl-4,5-dihydro-1H-pyrazole-3-carboxylate Synthesis according to method variant A using ethyl 2-(2-(4-methylphenyl)hydrazono)acetate (3 mmol, 619 mg, 1 eq.) and styrene (8.1 mmol, 844 mg, 2.7 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 3% EtOAc), the pyrazoline was obtained as a yellow solid (1.69 mmol, 522 mg, 56%). 1H NMR (400 MHz, CDCl3), δ / ppm: 7.35–7.30 (m, 2H, H-3'''), 7.31–7.19 (m, 3H, H-2''', H-4'''). 7.02 (d, J = 8.8 Hz, 2H, H-3'), 6.98 (d, J = 8.9 Hz, 2H, H-2'), 5.40 (dd, J = 13.3, 7.2 Hz, 1H, H-5), 4.34 (q, J = 7.1 Hz, 2H, H-2''), 3.71 (dd, J = 17.9, 13.3 Hz, 1H, (H-4)'), 3.04 (dd, J = 17.9, 7.2 Hz, 1H, (H-4)''), 2.23 (s, 3H, H-5'), 1.38 (t, J = 7.1 Hz, 3H, H-3''). 1 3 C NMR (101 MHz, CDCl3), δ / ppm: 162.9, 141.4, 140.4, 137.5, 130.7, 129.6, 129.3, 127.9, 125.7, 114.7, 65.6, 61.2, 42.2, 20.7, 14.5. HRMS (APCI+), m / z: calculated for [C19H20N2O2 + H] + 309.1598, found 309.1595. Example 52: Ethyl 1-(4-fluorophenyl)-5-phenyl-4,5-dihydro-1H-pyrazole-3-carboxylate Synthesis according to synthetic method variant A using ethyl 2-(2-(4-fluorophenyl)hydrazono)acetate (3 mmol, 631 mg, 1 eq.) and styrene (8.1 mmol, 844 mg, 2.7 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 3% EtOAc), the 20-pyrazoline was obtained as a yellow solid (2.58 mmol, 793 mg, 86%). 1H-NMR (400 MHz, CDCl3), δ / ppm: 7.36 – 7.30 (m, 2H, H-3 ), 7.30 – 7.24 (m, 1H, H-4 ), 7.24 – 7.19 (m, 2H, H-2’’’), 7.07 – 7.00 (m, 2H, H-2’), 6.91 – 6.83 (m, 2H, H-3’), 5.36 (dd, J = 13.2, 7.4 Hz, 1H, H-5), 4.33 (q, J = 7.1 Hz, 2H, H-2’’), 3.72 (dd, J = 18.0, 13.2 Hz, 1H, (H-4)’), 3.05 (dd, J = 18.0, 7.4 Hz, 1H, (H-4)’’), 1.37 (t, J = 7.1 Hz, 3H, H-3’’). 13 C-NMR (101 MHz, CDCl3), δ / ppm: 162.7, 159.2, 156.8, 141.0, 139.1, 139.1, 138.3, 129.4, 128.1, 125.8, 115.9, 115.8, 115.8, 115.5, 65.9, 61.3, 42.5, 14.4. 19 F-NMR (376 MHz, CDCl3), δ / ppm: -124.08 (tt, J = 8.7, 4.7 Hz). HRMS (ESI+), m / z: berechnet für [C 18 H 17 FN2O2+ Na] + 335.1166, gefunden 335.1168. Beispiel 53: Ethyl-1-(4-chlorphenyl)-5-phenyl-4,5-dihydro-1H-pyrazol-3-carboxylat CI Synthesis according to method variant A using ethyl 2-(2-(4-chlorophenyl)hydrazono)acetate (3 mmol, 680 mg, 1 eq.) and styrene (8.1 mmol, 844 mg, 2.7 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 3% EtOAc), the pyrazoline was obtained as a yellow solid (2.65 mmol, 872 mg, 88%). 1 H-NMR (400 MHz, CDCl3), δ / ppm: 7.34 – 7.28 (m, 2H, H-3'''), 7.30 – 7.20 (m, 1H, H-4'''), 7.19 – 7.15 (m, 2H, H-2'''), 7.12 – 7.06 (m, 2H, H-3'), 7.02 – 6.97 (m, 2H, H-2'), 5.35 (dd, J = 13.2, 7.0 Hz, 1H, H-5), 4.31 (q, J = 7.1 Hz, 2H, H-2''), 3.70 (dd, J = 18.1, 13.2 Hz, 1H, (H-4)'), 3.03 (dd, J = 18.1, 7.0 Hz, 1H, (H-4)''), 1.34 (t, J = 7.1 Hz, 3H, H-3''). 13 C-NMR (101 MHz, CDCl3), δ / ppm: 162.6, 141.3, 140.8, 139.0, 129.5, 129.0, 128.2, 126.3, 125.7, 115.8, 65.5, 61.5, 42.5, 14.5. HRMS (APCI+), m / z: calculated for [C18H17 35 ClN2O2 + H] + 329.1051, found 329.1044; calculated for [C18H1737 ClN2O2 + H] + 331.1028, found 331.1027. Example 54: Ethyl 1-(4-bromophenyl)-5-phenyl-4,5-dihydro-1H-pyrazole-3-carboxylate Synthesis according to synthetic method variant A using ethyl 2-(2-(4-bromophenyl)hydrazono)acetate (3 mmol, 813 mg, 1 eq.) and styrene (8.1 mmol, 844 mg, 2.7 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 3% EtOAc), the pyrazoline was obtained as an orange solid (2.80 mmol, 1044 mg, 93%). 1H-NMR (400 MHz, CDCl3), δ / ppm: 7.36 – 7.31 (m, 2H, H-3'''), 7.30 – 7.23 (m, 3H, H-3', H-4'''), 7.22 – 7.17 (m, 2H, H-2'''), 6.99 – 6.94 (m, 2H, H-2'), 5.37 (dd, J = 13.2, 7.0 Hz, 1H, H-5), 4.34 (q, J = 7.1 Hz, 2H, H-2''), 3.72 (dd, J = 18.2, 13.2 Hz, 1H, (H-4)'), 3.05 (dd, J = 18.1, 7.0Hz, 1H, (H-4)''), 1.37 (t, J = 7.1 Hz, 3H, H-3''). 1 3C-NMR (101 MHz, CDCl3), δ / ppm: 162.6, 141.7, 140.8, 139.1, 131.9, 129.5, 128.3, 125.7, 116.2, 113.8, 65.4, 61.5, 42.6, 14.5. HRMS (ESI+), m / z: calculated for [C18H17 79 BrN2O2 + H] + 373.0547, found 373.0546; calculated for [C18H17 81 BrN2O2 + H] + 375.0526, found 375.0530. Example 55: Ethyl 1-(2,4-dichlorophenyl)-5-phenyl-4,5-dihydro-1H-pyrazole-3-carboxylate Synthesis according to synthetic method variant A using ethyl 2-(2-(2,4-dichlorophenyl)hydrazono)acetate (3 mmol, 783 mg, 1 eq.) and styrene (8.1 mmol, 844 mg, 2.7 eq.). After 20 µl of flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 3% EtOAc), the pyrazoline was obtained as a yellow solid (2.51 mmol, 913 mg, 84%). 1H-NMR (400 MHz, CDCl3), δ / ppm: 7.31 (d, J = 8.8 Hz, 1H, H-6 ), 7.29 – 7.16 (m, 4H, H-3 , H-3 , H-4'''), 7.16 (dd, J = 7.7, 1.9 Hz, 2H, H-2'''), 7.07 (dd, J = 8.7, 2.4 Hz, 1H, H-5'), 5.90 (dd, J = 12.5, 6.0 Hz, 1H, H-5), 4.41 (qd, J = 7.1, 1.4 Hz, 2H, H-2''), 3.73 (dd, J = 18.0, 12.6 Hz, 1H, (H-4)'), 3.35 (dd, J = 18.0, 6.0 Hz, 1H, (H-4)''), 1.42 (t, J = 7.1 Hz, 3H, H-3''). 1 3 C NMR (101 MHz, CDCl3), δ / ppm: 162.5, 141.6, 139.7, 139.4, 130.5, 130.0, 128.9, 128.5, 127.4, 126.7, 126.5, 126.2, 67.8, 61.5, 41.4, 14.5. HRMS (APCI+), m / z: calculated for [C 18 H 16 35 Cl2N2O2+ H] + 363.0662, found 363.0658; calculated for [C 18 H 16 35 Cl 37 ClN2O2+ H] + 365.0635, found 365.0634; calculated for [C 18 H 16 37 Cl2N2O2+ H] + 367.0614, found 367.0613. Example 56: Ethyl 1-(perfluorophenyl)-5-phenyl-4,5-dihydro-1H-pyrazole-3-carboxylate Synthesis according to method variant A using ethyl 2-(2-(perfluorophenyl)hydrazono)acetate (3 mmol, 847 mg, 1 eq.) and styrene (8.1 mmol, 844 mg, 2.7 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 3% EtOAc), the pyrazoline was obtained as a brown oil (0.75 mmol, 288 mg, 25%). 1H-NMR (400 MHz, CDCl3), δ / ppm: 7.31 – 7.21 (m, 5H, H-2''', H-3''', H-4'''), 5.42 (dd, J = 12.5, 9.5 Hz, 1H, H-5), 4.35 (q, J = 7.1 Hz, 2H, H-2''), 3.65 (dd, J = 18.1, 12.5 Hz, 1H, (H-4)'), 3.23 (dd, J = 18.1, 9.5 Hz, 1H, (H-4)''), 1.35 (t, J = 7.1 Hz, 3H, H-3''). 1 3 C-NMR (101 MHz, CDCl3), δ / ppm: 162.2, 144.5, 142.5, 142.0, 139.1, 136.6, 129.2, 129.0, 128.8, 128.5, 126.8, 125.8, 118.3, 69.3, 61.8, 41.7, 14.4. 1 9 F-NMR (376 MHz, CDCl3), δ / ppm: -147.66 – -148.00 (m, F-3'), -158.85 (t, J = 21.7 Hz, F-4'), -163.46 – -163.63 (m, F-2'). HRMS (APCI+), m / z: calculated for [C 18 H 13 F5N2O2+ H] +385.0970, found 385.0967. 25 Example 57: Ethyl 1-(4-cyanophenyl)-5-phenyl-4,5-dihydro-1H-pyrazole-3-carboxylate (57) Synthesis according to method variant A using ethyl 2-(2-(4-cyanophenyl)hydrazono)acetate (3 mmol, 652 mg, 1 eq.) and styrene (8.1 mmol, 844 mg, 2.7 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 3% EtOAc), the pyrazoline was obtained as a yellow solid (2.71 mmol, 866 mg, 90%). 1H-NMR (400 MHz, CDCl3), δ / ppm: 7.46 – 7.41 (m, 2H, H-3''), 7.38 – 7.33 (m, 2H, H-3'''), 7.33 – 7.28 (m, 1H, H-4'''), 7.20 – 7.16 (m, 2H, H-2'''), 7.14 – 7.09 (m, 2H, H-2'), 5.43 (dd, J = 13.0, 6.4 Hz, 1H, H-5), 4.35 (q, J = 7.1 Hz, 2H, H-2''), 3.77 (dd, J = 18.4, 13.0 Hz, 1H, (H-4)'), 3.11 (dd, J = 18.4, 6.4 Hz, 1H, (H-4)''), 1.38 (t, J = 7.1 Hz, 3H, H-3''). 1 3C NMR (101 MHz, CDCl3), δ / ppm: 162.2, 145.7, 141.7, 140.1, 133.4, 129.7, 128.6, 125.5, 119.6, 114.5, 103.5, 64.9, 61.8, 42.8, 14.4. HRMS (ESI+), m / z: calculated for [C19H17N3O2+ H] + 320.1394, found 320.1393. Example 58: 4-(3,5-Diphenyl-4,5-dihydro-1H-pyrazol-1-yl)benzenesulfonic acid Synthesis according to synthetic method variant B using 4-(2-(2-ethoxy-2-oxoethylidene)hydrazinyl)benzenesulfonic acid (3.2 mmol, 884 mg, 1 eq.) and styrene (12.5 mmol, 1302 mg, 3.9 eq.). After reversed-phase flash column chromatography on C-18 silica with water / acetonitrile (50% → 80% MeCN), traces of the pyrazoline were obtained. 20 HRMS (ESI-), m / z: calcd for [C21H18N2O3S-H]- 377.0965, found 377.0953. Example 59: Ethyl 1-(2,4-dinitrophenyl)-5-phenyl-4,5-dihydro-1H-pyrazole-3-carboxylate Synthesis according to synthesis method variant A using ethyl 2-(2-(2,4-dinitrophenyl)hydrazono)acetate (2 mmol, 564 mg, 1 eq.) and styrene (5.4 mmol, 562 mg, 2.7 eq.). Dichloromethane was used as the organic solvent. Electrolysis was carried out at 35 °C. After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 3% EtOAc), the pyrazoline was obtained as an orange solid (0.57 mmol, 221 mg, 29%). 1H-NMR (400 MHz, CDCl3), δ / ppm: 8.46 (d, J = 2.6 Hz, 1H, H-3'), 8.13 (dd, J = 9.3, 2.6 Hz, 1H, H-5'), 7.37 – 7.28 (m, 3H, H-3''', H-4'''), 7.22 – 7.15 (m, 3H, H-6', H-2'''), 5.58 (dd, J = 12.3, 7.4 Hz, 1H, H-5), 4.35 (qd, J = 7.2, 1.0 Hz, 2H, H-2''), 3.81 (dd, J = 18.7, 12.3 Hz, 1H, (H-4)'), 3.20 (dd, J = 18.7, 7.5 Hz, 1H, (H-4)''), 1.38 (t, J = 7.1 Hz, 3H, H-3''). 1 3C NMR (101 MHz, CDCl3), δ / ppm: 161.4, 145.9, 140.3, 140.2, 138.6, 138.3, 129.9, 129.2, 127.2, 126.3, 122.2, 118.5, 66.2, 62.3, 43.2, 14.3. HRMS (APCI+), m / z: calculated for [C18H16N4O6 + NH4] + 402.1408, found 402.1406. Example 60: Ethyl 1-(4-methoxyphenyl)-5-phenyl-4,5-dihydro-1H-pyrazole-3-carboxylate Synthesis according to synthesis method variant A using ethyl 2-(2-(4-methoxyphenyl)hydrazono)acetate (3 mmol, 667 mg, 1 eq.) and styrene (8.1 mmol, 844 mg, 2.7 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 3% EtOAc), the pyrazoline was obtained as a yellow solid (1.58 mmol, 511 mg, 53%). 1H NMR (400 MHz, CDCl3), δ / ppm: 7.35–7.30 (m, 2H, H-3'''), 7.31–7.19 (m, 3H, H-2''', H-4'''). 7.06 – 7.01 (m, 2H, H-2’), 6.77 – 6.71 (m, 2H, H-3’), 5.36 (dd, J = 13.3, 7.6 Hz, 1H, H-5), 4.33 (q, J = 7.1 Hz, 2H, H-2’’), 3.71 (s, 3H, H-5’), 3.70 (dd, J = 17.9, 13.4 Hz, 1H, (H-4)’), 3.03 (dd, J = 17.9, 7.6 Hz, 1H, (H-4)’), 1.36 (t, J = 7.1 Hz, 3H, H-3’’). 1 3 C-NMR (101 MHz, CDCl3), δ / ppm: 162.9, 154.7, 141.4, 137.1, 136.7, 129.3, 128.0, 125.9, 116.1, 114.4, 66.2, 61.2, 55.6, 42.3, 14.5. HRMS (APCI+), m / z: berechnet für [C 19 H 20 N2O3+ H] + 325.1547, gefunden 325.1542. Beispiel 61: Ethyl-1-(4-trifluoromethoxyphenyl)-5-phenyl-4,5-dihydro-1H-pyrazol-3-carboxylat 5 Synthesis according to method variant A using ethyl 2-(2-(4-trifluoromethoxyphenyl)hydrazono)acetate (3 mmol, 829 mg, 1 eq.) and styrene (8.1 mmol, 844 mg, 2.7 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 3% EtOAc), the pyrazoline was obtained as an orange solid (0.98 mmol, 371 mg, 33%). 1H-NMR (400 MHz, CDCl3), δ / ppm: 7.38 – 7.32 (m, 2H, H-3'''), 7.31 – 7.26 (m, 1H, H-4'''), 7.24 – 7.20 (m, 2H, H-2'''), 7.10 – 7.06 (m, 2H, H-3'), 7.04 – 7.00 (m, 2H, H-2'), 5.37 (dd, J = 13.2, 7.2 Hz, 1H, H-5), 4.34 (q, J = 7.1 Hz, 2H, H-2''), 3.74 (dd, J = 18.1, 13.2 Hz, 1H, (H-4)'), 3.06 (dd, J = 18.1, 7.2 Hz, 1H, (H-4)''), 1.37 (t, J = 7.1 Hz, 3H, H-3''). 1 3 C-NMR (101 MHz, CDCl3), δ / ppm: 162.6, 143.3, 141.5, 140.8, 139.3, 129.5, 128.3, 125.7, 122.0, 121.9, 119.4, 115.3, 65.6, 61.4, 42.7, 14.4. 1 9 F NMR (376 MHz, CDCl3), δ / ppm: -59.4. HRMS (ESI+), m / z: calculated for [C19H17F3N2O3+ H] +379.1264, found 379.1264. 25 Example 62: 1-Methyl-3,5-diphenyl-4,5-dihydro-1H-pyrazole Synthesis according to method variant B using benzaldehyde methylhydrazone (3.2 mmol, 429 mg, 1 eq.) and styrene (12.5 mmol, 1302 mg, 3.9 eq.). After flash column chromatography on silica with cyclohexane / ethyl acetate (0% → 2% EtOAc), the pyrazoline was obtained as a yellow oil (0.76 mmol, 179 mg, 24%). 1H-NMR (400 MHz, CDCl3), δ / ppm: 7.69 – 7.64 (m, 2H, H-2''), 7.51 – 7.47 (m, 2H ¸H-2'''), 7.44 – 7.30 (m, 6H, H-3'', H-4'', H-3''', H-4'''), 4.13 (dd, J = 14.4, 10.0 Hz, 1H, H-5), 3.49 (dd, J = 16.1, 10.0 Hz, 1H, (H-4)'), 3.01 (dd, J = 16.1, 14.4 Hz, 1H, H-( H-4)''), 2.86 (s, 3H, H-1'). 1 3 C NMR (101 MHz, CDCl3), δ / ppm: 149.8, 140.5, 133.0, 128.8, 128.7, 128.6, 127.9, 127.6, 125.9, 73.7, 43.4, 41.7. HRMS (APCI+), m / z: calculated for [C16H16N2+ H] +237.1386, found 237.1386. Example 63: Alternative synthesis routes from 2,5-dichlorophenylhydrazine hydrochloride via (Z)-ethylglyoxylate-2,5-dichlorophenylhydrazone or (E)-ethylglyoxylate-2,5-dichlorophenylhydrazone to mefenpyr-diethyl (a) (Z)-ethylglyoxylate-2,5-dichlorophenylhydrazone (2) 0 In a 250-mL round-bottom flask, 2,5-dichlorophenylhydrazine hydrochloride (1a, 46.8 mmol, 10.0 g, 1.0 eq.) was dissolved in THF (75 mL) and cooled to 0°C. Triethylamine (56.2 mmol, 5.68 g, 1.2 eq.) was added dropwise, the mixture was stirred for 15 min, filtered, and the residue was washed with THF (25 mL). Ethyl glyoxylate (1b, 46.8 mol, 4.78 g, 1.0 eq.) in toluene (1:1 w / w) was added dropwise to the filtrate at 0°C. The mixture was then stirred for 5 h while reaching room temperature. The solvent was removed under reduced pressure, and the residue was recrystallized from cyclohexane / ethyl acetate (2:1 v / v) to give the product as a light yellow solid (2, 37.6 mmol, 9.82 g, 80%). 1H NMR (400 MHz, CDCl3), δ / ppm: 8.68 (s, 1H, H–1), 7.57 (d, J = 8.9 Hz, 1H, H–3'), 7.30–7.22 (m, 2H, H–3, 6'), 7.20 (dd, J = 8.9, 2.4 Hz, 1H, H–5'), 4.31 (q, J = 7.1 Hz, 2H, H–2''), 1.35 (t, J = 7.1 Hz, 3H, H–3''). 1 3C NMR (101 MHz, CDCl3), δ / ppm: 163.6, 137.6, 129.1, 128.9, 128.3, 126.9, 118.5, 116.4, 61.3, 14.3. HRMS (ESI+), m / z: calculated for C 10 H 10 35 Cl2N2O2+ H + 261.0192 [M+H] + , found 261.0192; calculated for C 10 H 10 35 Cl 37 ClN2O2+ H + 263.0164 [M+H] + , found 263.0164; calculated for C 10 H 10 37 Cl2N2O2+ H + 265.0138 [M+H] + , found 265.0137. LC-MS analysis: Water + 0.1 vol% formic acid / MeCN (50 → 100% MeCN in 10 min, 10 min 100% MeCN) R t = 9.910 min (b) (E)-ethylglyoxylate-2,5-dichlorophenylhydrazone (3) CI In a 2 L round-bottom flask, ethyl glyoxylate (1b, 0.79 mol, 80.7 g, 1.05 eq.) in toluene (1:1 w / w) and 2,5-dichlorophenylhydrazine hydrochloride (1a, 0.75 mol, 160.1 g, 1.0 eq.) in ethanol (750 mL) were dissolved. Glacial acetic acid (0.75 mol, 45.0 g, 1.0 eq.) was added, and the mixture was heated to reflux overnight. After crystallization of the product at -30°C, the product was filtered off, and the residue was washed with water. The product was obtained without further purification as orange needles (3, 0.67 mol, 174.5 g, 89%). 3' (t, J = 7.1 Hz, 3H, H-3''). 1 3 C NMR (101 MHz, CDCl3), δ / ppm: 163.5, 138.5, 129.1, 128.2, 127.0, 121.6, 119.6, 115.4, 61.0, 14.3. LC-MS analysis: water + 0.1 vol% formic acid / MeCN (50 → 100% MeCN in 10 min, 10 min 100% MeCN) Rt = 14.049 min (c) (Z)-Ethylglyoxylate-2,5-dichlorophenylhydrazone to mefenpyr-diethyl (4) CI In a jacketed 50-mL beaker cell, (Z)-ethylglyoxylate 2,5-dichlorophenylhydrazone (2, 19.1 mmol, 5.0 g, 1.0 eq.) and ethyl methacrylate (61.5 mmol, 7.02 g, 3.21 eq.) were dispersed in 1 M aqueous sodium iodide (20 mL). Isostatic graphite plates (size: 60 × 20 × 3 mm) with an immersion depth of 2.7 cm and a relevant anode area of ​​5.4 cm were used as the anode and cathode. 2 A constant current electrolysis was carried out at 33°C and 1000 rpm with a current density of 27.9 mA cm -2carried out until a charge of 5.4 F was applied. The biphasic mixture was transferred to a separatory funnel for separation. The aqueous layer was further extracted with ethyl acetate (1 × 30 mL), the combined organic fractions were dried over anhydrous magnesium sulfate, filtered, and the solvent was removed under reduced pressure to give the crude product. After flash column chromatography on silica with cyclohexane / EtOAc (0% → 4% EtOAc), mefenpyr diethyl was obtained as an orange oil (4, 16.4 mmol, 6.13 g, 86%). 1 H NMR (400 MHz, CDCl3), δ / ppm: 7.41(d, J = 2.1 Hz, 1H, H-3'), 7.25–7.19 (m, 2H, H-5', H-6'), 4.33 (qd, J = 7.2, 1.7 Hz, 2H, H-2''), 4.19 (q, J = 7.2 Hz, 2H, H-2'''), 3.73 (d, J = 17.7 Hz, 1H, (H-4)'), 3.12 (d, J = 17.7 Hz, 1H, (H-4)''), 1.46 (s, 3H, H-1''''), 1.35 (t, J = 7.1 Hz, 3H, H-3''), 1.24 (t, J = 7.1 Hz, 3H, H-3'''). 13C NMR (101 MHz, CDCl3), δ / ppm: 171.5, 162.3, 140.1, 138.0, 133.6, 133.4, 130.5, 130.2, 127.5, 73.6, 62.3, 61.5, 45.1, 22.1, 14.5, 14.1. HRMS (ESI+), m / z: calculated for C16H18 35 Cl2N2O4 + H + 373.0716 [M+H] + , found 373.0718; calculated for C16H18 35 Cl 37 ClN2O4 + H + 375.0690 [M+H] + , found 375.0692; calculated for C16H18 37 Cl2N2O4 + H + 377.0669 [M+H] + , found 377.0674.

[0007] (d) (E)-Ethylglyoxylate-2,5-dichlorophenylhydrazone to Mefenpyr-diethyl (4) CI Hydrazone 3 and ethyl methacrylate were dissolved in an organic solvent in 5 ml PTFE cells, and aqueous sodium halide solution was added. Isostatic graphite plates (size: 70 × 10 × 3 mm) with an immersion depth of 1.7 cm and a relevant anode area of ​​1.7 cm were used as the anode and cathode. 2used. The mixture was subjected to galvanostatic electrolysis with vigorous stirring (magnetic stirrer set at approximately 1000 rpm) at 33°C until a charge of 5.4 F was applied. The mixture was transferred to a separatory funnel, and the cell was rinsed with ethyl acetate. 1 mL of a solution of 1,3,5-trimethoxybenzene (3.000 g / 100 mL ethyl acetate) was added as an internal standard. The mixture was shaken briefly, and the layers were separated. The organic fraction was dried over anhydrous magnesium sulfate and filtered. An aliquot was filtered through silica gel and analyzed by GC to quantify the amount of pyrazoline. Due to poor conversion and yield when using (E)-hydrazone 3 under conditions optimized for (Z)-hydrazone 2, a second screening was performed. Initially, the solvent and halide source were investigated.This resulted in tert-butyl methyl ether and sodium iodide as preferred conditions (Table 1). Table 1: Solvent screening for the conversion of (E)-ethyl glyoxylate 2,5-dichlorophenylhydrazone a. m - ec er ve e, m org. sungsm e , m aq. a , , mmo y razon , 3.21 eq. Ethyl methacrylate, 33 °C, isostatic graphite electrodes, 27.9 mA cm -2 , 5.4 F. determined after external calibration with 1,3,5-trimethoxybenzene as internal standard. Preferred conditions for the (E)-hydrazone are as follows: Cl 5 mL PTFE beaker cuvette, 1 mL MeO t Bu, 4 ml 1 M aq. NaI, 0.60 mmol hydrazone 3. Alternatively, the (E)-hydrazone can preferably be reacted in a mixture of ethanol and acetonitrile (especially 1:1 vol / vol), with a yield of up to 73% (optimized conditions: 3.79 eq. methacrylate, 2.79 eq. NaI, 5 mA / cm2, 4.0 F, rt): CI II org.solvent,Nal j,Q,T .

Claims

Claims:

1. Process for the preparation of compounds of general formula (I) wherein g stands; R 1 is alkyl, -C(O)O-alkyl, cycloalkyl, aryl, or heterocyclyl, each substituted or unsubstituted; R 2 is alkyl, -C(O)O-alkyl, cycloalkyl, aryl, or heterocyclyl, each substituted or unsubstituted; R 3 is alkyl, -C(O)O-alkyl, -C(O)O-aryl, -C(O)N-(alkyl)2, -CN, -P(O)(O-alkyl)2, cycloalkyl, aryl, or heterocyclyl, each substituted or unsubstituted, or H; R 4 exists if represents a single bond and R 4 is alkyl, -C(O)O-alkyl, C(O)O-aryl, cycloalkyl, aryl, or heterocyclyl, each substituted or unsubstituted, or H; or R 3 and R 4 together with the carbon atom in the compounds of formula (I), the R 3 and R 4a substituted or unsubstituted cycloalkyl or heterocyclyl; R 5 is alkyl, -C(O)O-alkyl, cycloalkyl, aryl, or heterocyclyl, each substituted or unsubstituted, or H; or R 4 and R 5 together with the carbon atoms in the compounds of formula (I) which R 4 and R 5 together, a cycloalkyl or heterocyclyl, each substituted or unsubstituted; or R 1 and R 5 together with the carbon atoms in the compounds of formula (I) which R 1 and R 5 a cycloalkyl or heterocyclyl, each substituted or unsubstituted; characterized in that compounds of the general formula (II) with II where R 1 and R 2have the same meaning as in the general formula (I), in the presence of an iodide source, electrochemically with a compound of the formula (III) or (IV), 3 ) I where R 3 , R 4 and R 5 have the same meaning as in the general formula (I).

2. The process according to claim 1, wherein R 1 unsubstituted or substituted C1-C6 alkyl, unsubstituted or substituted - C(O)O(C 1-8 -alkyl), unsubstituted or substituted C3-C 12 -cycloalkyl, unsubstituted or substituted phenyl, unsubstituted or substituted naphthyl; and / or R 2 is unsubstituted or substituted C1-C6 alkyl, unsubstituted or substituted - C(O)O(C 1-8 -alkyl), unsubstituted or substituted C3-C 12 -cycloalkyl, unsubstituted or substituted phenyl; and / or R 3is H, unsubstituted or substituted C1-C6-alkyl, unsubstituted or substituted -C(O)O(C1-8-alkyl), unsubstituted or substituted -C(O)O-phenyl, unsubstituted or substituted -C(O)O-benzyl, unsubstituted or substituted C3-C12-cycloalkyl, unsubstituted or substituted phenyl, unsubstituted or substituted naphthyl; 20 and / or R 4 is present if it represents a single bond and R 4 is H, unsubstituted or substituted C1-C6-alkyl, unsubstituted or substituted C(O)O(C1-8-alkyl), unsubstituted or substituted C(O)O-phenyl, unsubstituted or substituted - C(O)O-benzyl, unsubstituted or substituted C3-C 12 -cycloalkyl, unsubstituted or substituted phenyl; or R 3 and R 4 together with the carbon atom in the compounds of formula (I), form the R 3 and R 4connects an unsubstituted or substituted C3-C 12 -cycloalkyl; and / or R 5 is H, unsubstituted or substituted C1–C6 alkyl, unsubstituted or substituted C(O)O(C 1-8 -alkyl), unsubstituted or substituted C3-C 12 -Cycloalkyl, substituted or unsubstituted phenyl; or or R 4 and R 5 together with the carbon atoms, the R 4 and R 5 combine with each other in the compounds of formula (I), an unsubstituted or substituted C3- C 12 -cycloalkyl or heterocyclyl; or R 1 and R 5 together with the carbon atoms in the compounds of formula (I) which R 1 and R 5 connect an unsubstituted or substituted C3-C 12-Cycloalkyl or heterocyclyl.

3. The process according to claim 1 or 2, wherein the iodide source is used in the form of sodium iodide, lithium iodide, potassium iodide, or mixtures thereof.

4. The process according to any one of claims 1 to 3, wherein the reaction takes place in the presence of the iodide source in an aqueous solution.

5. The process according to claim 4, wherein the iodide source is used in a concentration of 0.2 to 2.0 M, based on the aqueous solution, preferably 0.5 to 1.4 M, based on the aqueous solution.

6. The process according to any one of claims 1 to 5, wherein the reaction takes place in the presence of the iodide source in a two-phase mixture of an aqueous solution and an organic solvent, wherein the organic solvent is preferably selected from ethyl acetate, tert-butyl methyl ether, dichloromethane, chlorobenzene, 1,2-dichloroethane, or mixtures thereof.Process according to one of claims 1 to 6, wherein the compound (III) or (IV) is used in amounts of between 1.0 and 6.0 equivalents, based on the amount of substance of the compounds of formula (II) used, preferably between 2.0 and 5.0 equivalents.

8. The process according to any one of claims 1 to 7, wherein the reaction is carried out in an undivided electrolysis cell.

9. The process according to any one of claims 1 to 8, wherein graphite electrodes are used as anode and cathode.

10. The process according to claim 9, wherein isostatic graphite is used.

11. The process according to any one of claims 1 to 10, wherein the process is carried out at a current density of 20 to 50 mA / cm², preferably 30 to 40 mA / cm².

12. The process according to any one of claims 1 to 11, wherein the process is carried out until an applied charge of 1 to 10 F, preferably 2 to 6 F, is reached.

13. The process according to any one of claims 1 to 12, wherein the reaction takes place at a temperature of 10 to 50 °C, preferably 20 to 40 °C.

14. The process according to any one of claims 1 to 13, wherein the aqueous phase is subsequently separated and optionally subsequently freeze-dried to recover the iodide source. 15.Method according to one of claims 1 to 14, wherein. represents a single bond, and compounds of general formula (II) are reacted with compounds of general formula (III).

16. The process according to any one of claims 1 to 15, wherein compound (I) is represented by diethyl 1-(2,4-dichlorophenyl)-5-methyl-4,5-dihydro-1H-pyrazole-3,5-dicarboxylate, compound (II) is represented by ethyl 2-(2-(2,4-dichlorophenyl)hydrazono)acetate; and compound (III) is represented by ethyl methacrylate.

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