Use of a pincer-type pnp manganese complex catalyst

Abstract

The application relates to application of a Pincer type PNP manganese complex catalyst and belongs to the technical field of catalysis processes. The application relates to application of a Pincer type PNP manganese complex catalyst in catalyzing a dehydrogenation coupling reaction of compound I and compound II, wherein the compound I is a compound containing an A group directly connected with carbon, the compound II is a compound containing a 1H-indole ring with hydrogen at a C3 position being unsubstituted, and the structure of the A group is -CH(R 1 )R 2 OH, wherein R 1 is -H or a phenyl group, and R 2 is methylene or is not present. The application has the advantages of being cheap, low-toxic, having a wide source of raw materials and good atomic economy compared with metal catalysts or other synthesis methods, and has the advantages of wide substrate applicability and high reaction efficiency (a yield of more than 99% at most) compared with existing cheap metal catalytic systems.

Description

Technical Field

[0001] This invention relates to the application of a Pincer-type PNP manganese complex catalyst, belonging to the field of catalytic process technology. Background Technology

[0002] Indole, a common heterocyclic skeleton, is widely found in everyday commodities, various natural products, and advanced materials. Later, it was discovered that indole is also a skeletal unit in medicinal alkaloids, fungal metabolites, and marine natural products. As an important structural skeleton for many drugs, indole derivatives, with their high biological activity, occupy a place in drugs used in multiple therapeutic areas, including antihypertensive, antiproliferative, antiviral, antitumor, analgesic, anti-inflammatory, and antibacterial applications. For example, C3-alkenylindole also possesses various anticancer, antibacterial, and antiviral biological activities and is an important precursor for the synthesis of many important biologically related molecules, such as indole alkaloids and carbazole. Due to the important role of indole in medicinal chemistry, much effort has been devoted to the synthesis of functionalized indoles. With the innovation of modern synthetic methods and the dedicated efforts of synthetic chemists, the construction and modification of indole-containing rings has gradually become an important research branch of synthetic chemistry, achieving a series of research advances and giving rise to many classic reactions.

[0003] In recent years, the development of catalysts using inexpensive metals instead of precious metals has garnered significant attention in the fields of catalysis and sustainable development in organic synthesis. One ideal method is to explore inexpensive metal catalysts using hydrogen-based approaches to efficiently dehydrogenate alcohols and indoles into C3-substituted indoles. In this area, the use of inexpensive metal complexes such as Fe, Cu, Co, and Ni for the C3-alkylation of indoles has been reported. For example, Morrill et al. disclosed iron-catalyzed C3-methylation of indoles in *ACS Catalysis* (ACS Catal. 2018, 8, 6440-6445), and Liu Zhiming et al. disclosed cobalt-catalyzed C3-methylation of indoles in *Organic Letters* (Org. Lett. 2017, 19, 5228-5231). However, these catalysts exhibit poor substrate applicability or low reaction efficiency in the catalytic C3-alkylation of indoles, making it difficult to balance applicability and efficiency. Summary of the Invention

[0004] The purpose of this invention is to provide an application of a Pincer-type PNP manganese complex catalyst, which exhibits broad substrate adaptability and high reaction efficiency in catalyzing the dehydrogenation coupling reaction of compounds I and II.

[0005] To achieve the above objectives, the technical solution adopted by this invention is as follows:

[0006] The application of Pincer-type PNP manganese complex catalysts in the dehydrogenation coupling reaction of compounds I and II, wherein compound I is a compound containing an A group directly attached to carbon, and compound II is a compound containing a 1H-indole ring with an unsubstituted hydrogen at the C3 position; the structure of the A group is shown in Formula I:

[0007]

[0008] In formula I, R 1 For -H or phenyl, R 2 If methylene is present or absent, an asterisk "*" indicates the connection point between group A and the rest of the molecule of compound I.

[0009] The application of the Pincer-type manganese complex catalyst of the present invention has the advantages of being inexpensive, low in toxicity, having a wide range of raw material sources, and having good atom economy compared with metal catalysts or other synthesis methods. Compared with existing inexpensive metal catalytic systems, it has the advantages of wide substrate applicability and high reaction efficiency (the yield can reach more than 99%).

[0010] It should be noted that when R 2 When the methylene group is present, the Pincer-type PNP manganese complex catalyst can catalyze the direct formation of C3-alkenylindole compounds from compounds I and II.

[0011] Understandably, R 2 When A is absent, the structure of the A group is as shown in Formula III:

[0012]

[0013] Furthermore, the structure of the Pincer-type PNP manganese complex catalyst is shown in Formula II:

[0014]

[0015] In Equation II, R 3 X is -H, R is -Br, and R is isopropyl. i One of Pr, cyclohexyl (Cy), or phenyl (Ph).

[0016] It is understood that when R is isopropyl, the Pincer-type PNP manganese complex is catalyst [Mn]-1; when R is cyclohexyl, the Pincer-type PNP manganese complex is catalyst [Mn]-2; and when R is phenyl, the Pincer-type PNP manganese complex is catalyst [Mn]-3. The structures of catalysts [Mn]-1, [Mn]-2, and [Mn]-3 are as follows:

[0017]

[0018] Furthermore, the dehydrogenation coupling reaction involves reacting compound I and compound II in an organic solvent at 140–165°C under the action of a base and the Pincer-type PNP manganese complex catalyst. The dehydrogenation coupling reaction is carried out under closed conditions. Before the reaction, compound II, compound I, the base, the Pincer-type PNP manganese complex catalyst, and the organic solvent are added to the reactor sequentially. After the reaction is completed, the reaction system is cooled using an ice-water bath.

[0019] Furthermore, the reaction time at 140–165°C is ≥6 hours, for example, 16 hours.

[0020] Further, the alkali is one or any combination of alkali metal hydroxide, alkali metal alkoxide, and alkali metal carbonate. Further, the alkali metal hydroxide is sodium hydroxide and / or potassium hydroxide. The alkali metal alkoxide is sodium ethoxide (EtONa), sodium tert-butoxide (... t BuONa), potassium tert-butoxide ( t One or any combination of the alkali metal carbonates (BuOK). The alkali metal carbonate is potassium carbonate.

[0021] Furthermore, the organic solvent is one or any combination of dioxane, toluene, and tetrahydrofuran (THF).

[0022] Furthermore, the molar ratio of compound I to compound II is ≥2:1, for example, the molar ratio of compound I to compound II is 2:1.

[0023] Furthermore, the amount of base used for every 0.25 mmol of Compound II is 0.25–0.35 mmol. Even further, the amount of base used for every 0.25 mmol of Compound II is 0.3 mmol.

[0024] Furthermore, the volume of organic solvent used for each 0.25 mmol of compound II is 0.5–1.2 mL. Even further, the volume of organic solvent used for each 0.25 mmol of compound II is 0.8 mL.

[0025] Furthermore, the amount of the Pincer-type PNP manganese complex catalyst used is 2 mol% of the compound amount. For example, the amount of Pincer-type PNP manganese complex catalyst used corresponds to 0.005 mmol of compound II for every 0.25 mmol of compound II.

[0026] For example, the standard reaction of dehydrogenation conversion of indole and phenylethanol is as follows:

[0027]

[0028] Furthermore, compound I is a compound containing an aromatic ring or a heteroaromatic ring in its molecule, and the A group is directly connected to the cyclic carbon of the aromatic ring or heteroaromatic ring.

[0029] Further, the heteroaromatic ring is a thiophene ring or a pyridine ring, and the aromatic ring is a benzene ring or a naphthalene ring. Even further, in the aromatic ring or heteroaromatic ring, only one carbon atom is substituted with the A group, or in the aromatic ring or heteroaromatic ring, two or more carbon atom atoms are substituted, with one carbon atom substituted with the A group, and the hydrogen atoms on the other carbons independently substituted with one of the following groups: alkyl, alkoxy, phenyl, haloyl, or haloalkyl. Preferably, the hydrogen atoms on the other carbons are independently substituted with one of the following groups: C1-C4 alkyl, C1-C4 alkoxy, phenyl, haloyl, or C1-C4 haloalkyl.

[0030] Furthermore, the halogroup is one of -F, -Cl, -Br, and -I. The haloalkyl group is -CF3.

[0031] Furthermore, the compound of formula I is selected from one of the following compounds:

[0032]

[0033] Furthermore, compound I is a fatty alcohol with ≥3 carbon atoms, and group A is -CH2CH2OH.

[0034] Further, compound I is a straight-chain fatty alcohol. Further, the straight-chain fatty alcohol is CH3CH2CH2OH, CH3CH2CH2CH2OH, CH3CH2CH2CH2CH2OH, CH3CH2CH2CH2CH2CH2OH, or CH3CH2CH2CH2CH2CH2CH2OH.

[0035] Furthermore, compound II has the structure shown in the following formula:

[0036]

[0037] In formula IV, R 4 R 5 R 6 R 7 R 8 It is independently selected from one of -H, alkyl, alkoxy, halogroup, and phenyl. Furthermore, R in formula IV... 4 R 5 R 6 R7 R 8 It is independently selected from one of -H, C1-C4 alkyl, C1-C4 alkoxy, halogroup, and phenyl.

[0038] Furthermore, compound II is selected from one of the following compounds:

[0039]

[0040] Furthermore, after the dehydrogenation coupling reaction is completed, the product can be separated and purified by column chromatography.

[0041] In this invention, "aryl" refers to the organic group formed after the loss of a hydrogen atom from a carbon atom on an aromatic ring of an aromatic hydrocarbon molecule. If the aryl group is to be substituted, the substitution can occur independently of each other in the form of mono- or poly-substitution on all the hydrogen-carrying carbon atoms in each case. The aryl group itself is a substituent attached to the molecule through the carbon atom of the aromatic ring, such as phenyl, naphthyl, and biphenyl.

[0042] "Heteroaryl" refers to a monocyclic heteroaryl ring or a polycyclic ring having at least one heteroaryl ring, which, compared to the corresponding aryl or cycloalkyl (cycloalkenyl) group, contains one or more identical or different heteroatoms independently selected from nitrogen, sulfur, and oxygen, wherein the resulting group must be chemically stable. If a heteroaryl group is to be substituted, the substitution can occur independently of each other in the form of monosubstituted or polysubstituted substitutions on all hydrogen-carrying carbon and / or nitrogen atoms in each case. The heteroaryl group itself acts as a substituent linked to the molecule via the cyclic carbon atom.

[0043] "alkyl" refers to an organic group obtained by removing one hydrogen atom from a straight-chain or branched alkane; "alkylene" refers to an organic group obtained by losing two hydrogen atoms from the same carbon atom or from two different carbons of a straight-chain or branched alkane, such as "-CH2-"; "alkoxy" refers to an organic group formed by attaching an alkyl group to an oxygen atom, such as "-O-CH3" (-OMe); halogen groups are -F, -Cl, -Br or -I; haloalkyl refers to an organic group formed by replacing the hydrogen atom on the carbon atom of an alkyl group with a halogen group. Detailed Implementation

[0044] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0045] The structures of catalysts [Mn]-1, [Mn]-2, [Mn]-3, [Mn]-4, [Mn]-5, and [Mn]-6 used in the following examples and comparative examples are as follows:

[0046]

[0047] The catalyst [Mn]-1 (PNP(Ph)-Mn(CO)2Br catalyst) was prepared by a method including the following steps:

[0048] Under an argon atmosphere, [Mn(CO)5Br] (0.44 mmol) and [PNP-] were added to a 25 mL Schlenk flask. i [Pr] (0.48 mmol) and degassed toluene (10 mL) were added, and the reaction was heated to 110 °C and stirred for 4 h. After the reaction was completed, the residue was filtered off, toluene was dried under vacuum, 10 mL of degassed n-hexane was added, and the mixture was filtered under argon. The filter cake was dried under vacuum to give a light yellow solid (70%). The reaction involved is as follows:

[0049]

[0050] MRI: 1 H NMR (400MHz, C6D6) δ3.27(d,J=6.9Hz,2H),2.79(s,1H),2.43(d,J=13.3Hz,2H),2.21(d,J=7.3Hz,2H),1.98–1.84(m,2H),1.64(s,2H) ,1.51(dd,J=15.1,7.3Hz,6H),1.31(dd,J=13.9,6.9Hz,6H),1.21(dd,J=13.1,7.1Hz,6H),1.06(dd,J=10.9,6.9Hz,6H),0.85(s,2H), 13 C NMR (101MHz, C6D6) δ52.33, 26.77 (t, J = 9.3Hz), 25.78 (t, J = 9.3Hz), 24.10 (d, J = 9.5Hz), 19.88 (d, J = 16.5Hz), 18.51, 18.05. 31 P NMR (162MHz, C6D6) δ 81.23 (s).

[0051] High resolution: HR-MS (ESI) called for C 18 H 37 MnNO2P2[M] + 416.1674; found: 416.1675.

[0052] Infrared: 3180, 2915, 2870, 1901, 1809, 1458, 1367, 1251, 1054, 956, 827, 653, 626, 599 cm -1 .

[0053] The catalysts [Mn]-2, [Mn]-3, [Mn]-4 and [Mn]-5 were synthesized using the methods described in the references (Chem. Sci. 2017, 8, 3576; J. Am. Chem. Soc. 2017, 139, 11941; Angew. Chem. Int. Ed. 2018, 57, 13439.).

[0054] The catalyst [Mn]-6 (imidazolium NNP-Mn(CO)2Br catalyst) was prepared by a method including the following steps:

[0055] 1) Synthesis of 2-chloro-N,N-di(trimethylsilyl)ethylamine

[0056]

[0057] Add 4.6 g (40 mmol) of 2-chloroethylamine hydrochloride, 18 mL (132 mmol) of triethylamine (NEt3), and 50 mL of dichloromethane to a Shrek flask. Add 20 mL of a dichloromethane solution of trimethylchlorosilane (TMSCl, 90 mmol, 9.8 g, 11.4 mL) to the resulting system and stir at room temperature for 12 h. After the reaction is complete, remove excess triethylamine, trimethylchlorosilane, and dichloromethane under reduced pressure. Add 60 mL of n-hexane to the residue and stir at room temperature for 30 min. Filter to remove NEt3·HCl. Remove n-hexane by rotary evaporation of the filtrate using a rotary evaporator, and then perform vacuum distillation using an oil pump. The fraction obtained is the target product (yield 6.0 g, 68% yield).

[0058] MRI: 1 H NMR (400MHz, CDCl3) δ3.37–3.21(m,2H),3.18–2.99(m,2H),0.14(s,18H). 13 C NMR (101MHz, CDCl3) δ47.38, 44.83, 1.89.

[0059] 2) Synthesis of diphenylphosphine

[0060]

[0061] Under argon protection at -78°C, a tetrahydrofuran solution (20 mL) of diphenylphosphine hydrogen (1.86 g, 10 mmol) was added to a Shrek flask, followed by the slow dropwise addition of a hexane solution of n-butyllithium (2.5 mol / L, 4.4 mL, 11 mmol). After the addition was complete, the reaction system was slowly heated to room temperature and stirred for 2 h at room temperature. Then, the Shrek flask was cooled to 0°C using an ice-water bath, and 2-chloro-N,N-di(trimethylsilyl)ethylamine (2.45 g, 11 mmol) was slowly added. The reaction was then carried out at 80°C. The reaction was refluxed for 12 h under the specified conditions. After the reaction was completed, the resulting system was cooled to room temperature, 5 mL of water and 6 mL of 2.0 mmol / mL sulfuric acid were added, and the mixture was stirred for 1 h. Then, 7 mL of 4.0 mmol / mL sodium hydroxide solution was added, and the mixture was stirred for 0.5 h. The organic phase was separated, and the aqueous phase was extracted with diethyl ether (3 × 20 mL). The resulting organic phases were combined, dried over anhydrous sodium sulfate, and then evaporated to dryness to obtain the crude product (the crude product yield was 2.06 g, and the crude yield was 95%). The crude product was used directly for the next step without further column chromatography separation.

[0062] 3) Synthesis of imidazole NNP ligands

[0063]

[0064] Under argon protection and at room temperature, a tetrahydrofuran solution (6 mL) of imidazole formaldehyde (110 mg, 1.0 mmol) was added to a Shrek flask, followed by a tetrahydrofuran solution (6 mL) of diphenylphosphine ethylamine (290 mg, 1.0 mmol). The reaction was carried out for 1 h at room temperature. Afterward, the tetrahydrofuran was removed by pumping through the Shrek line connected to the cold trap, and 6 mL of toluene was added. Then, a toluene solution (1.5 mol / L) of diisobutylaluminum hydride (DIBAL) was added under ice-water bath conditions. The reaction was carried out at room temperature for 2 hours (1.2 mL, 1.8 mmol of diisobutylaluminum hydride), followed by quenching with 10 mL of water. The organic phase was separated, and the aqueous phase was extracted with diethyl ether (3 × 20 mL). The organic phases were combined, dried over anhydrous sodium sulfate, and then evaporated to dryness. The product was separated by column chromatography (using a mixture of dichloromethane and methanol as the eluent, with a volume ratio of 20:1) to obtain a pale yellow oily liquid, which was the target product (yield of 210 mg, yield of 65%).

[0065] MRI: 1H NMR(400MHz, CDCl3)δ7.41(ddt,J=7.4,5.4,2.7Hz,4H),7.35–7.29(m,6H),6.91(d,J=1.3Hz,1H),6 .80(d,J=1.3Hz,1H),3.82(s,2H),3.64(s,3H),2.86–2.74(m,2H),2.31–2.23(m,2H),1.77(b,1H). 13 C NMR(101MHz, CDCl3) δ146.3,138.3(d,J=12.4Hz),132.7(d,J=18.7Hz),128.6,128 .4(d,J=6.7Hz),127.1,121.2,46.2(d,J=20.3Hz),45.6,32.7,28.9(d,J=12.4Hz). 31 P NMR (162MHz, CDCl3) δ-20.76 (s).

[0066] High resolution: HRMS(ESI)calcd.for C 19 H 22 N3P[M+H] + :324.1624; found:324.1610.

[0067] 4) Synthesis of imidazole NNP-Mn(CO)2Br catalyst

[0068] The reaction equation is shown below:

[0069]

[0070] In an argon-filled glove box, imidazole NNP ligand (210 mg, 0.65 mmol) and manganese pentacarbonyl bromide (165 mg, 0.60 mmol) were added to a Shrek flask and refluxed at 110 °C for 12 h. After the reaction was completed, the resulting system was cooled to room temperature, and a yellow precipitate was formed. The precipitate was filtered and washed with toluene (2 × 1 mL), then washed with diethyl ether (3 × 5 mL), and finally dried under vacuum to obtain the target catalyst (yield of 260 mg, yield of 80%).

[0071] MRI: 1H NMR(400MHz, DMSO-d6)δ7.76(t,J=7.6Hz,2H),7.55(m,3H),7.45–7.34(m,5H),7.07(s,1H),6.42(s,1H), 4.32(d,J=16.8Hz,1H),4.08(d,J=16.8Hz,1H),3.56(s,3H),3.14(m,1H),2.87–2.69(m,1H),2.27(m,2H). 13 C NMR(101MHz,DMSO-d6)δ149.8,132.7,132.3,132.0,131.9,131.7,131.4,131.0,130.9,129.7(d, J=9.5Hz), 129.4 (d, J=9.3Hz), 128.1, 125.2, 54.9 (d, J= 11.4Hz), 49.7, 34.7, 22.5 (d, J= 22.6Hz). 31 P NMR (162MHz, DMSO-d6) δ63.97 (s).

[0072] High resolution: HRMS(ESI)calcd.for C 22 H 22 BrMnN3O3P[M-Br] + :462.0774; found:462.0775.

[0073] Example 1

[0074] The application of the Pincer-type PNP manganese complex catalyst in the dehydrogenation coupling reaction of compound I and compound II in this embodiment, where compound I is benzyl alcohol and compound II is 1H-indole, includes the following steps:

[0075] In a glove box, 1H-indole (29 mg, 0.25 mmol), benzyl alcohol (54 mg, 0.5 mmol), potassium hydroxide (16.8 mg, 0.3 mmol), catalyst [Mn]-1 (2.5 mg, 0.005 mmol), and dioxane (0.8 mL) were added sequentially to a 15 mL pressure-resistant tube equipped with a stir bar. The cap was tightened, and the pressure-resistant tube was placed in a metal module and reacted at 165 °C for 16 hours. After the reaction was complete, the tube was cooled in an ice-water bath, the cap was carefully opened, and the reaction product was quantitatively analyzed by gas chromatography (GC). The yield was 99%.

[0076] MRI: 1H NMR (400MHz, CDCl3) δ7.77(s,1H),7.44(d,J=7.8Hz,1H),7.26–7.16(m,5H),7.14–7.08(m,2H),7.01-6.97(m,1H),6.83–6.75(m,1H),4.03(s,2H). 13 C NMR (101MHz, CDCl3) δ141.26,136.48,128.74,128.38,127.51,125.93,122.38,122.09,119.41,119.20,115.87,111.11,31.64.

[0077] The chemical reactions involved are as follows:

[0078]

[0079] Example 2

[0080] The application of the Pincer-type PNP manganese complex catalyst in the dehydrogenation coupling reaction of compounds I and II in this embodiment differs from that in Example 1 only in that the catalyst [Mn]-1 in Example 1 is replaced with catalyst [Mn]-2, with a yield of 82%.

[0081] Example 3

[0082] The application of the Pincer-type PNP manganese complex catalyst in the dehydrogenation coupling reaction of compounds I and II in this embodiment differs from that in Example 1 only in that the catalyst [Mn]-1 in Example 1 is replaced with catalyst [Mn]-3, with a yield of 77%.

[0083] Examples 4-22

[0084] Examples 4-22 illustrate the application of Pincer-type PNP manganese complex catalysts in the dehydrogenation coupling reaction of compounds I and II, including the following steps:

[0085] In a glove box, compound II (0.25 mmol), compound I (0.5 mmol), potassium hydroxide (16.8 mg, 0.3 mmol), catalyst [Mn]-1 (2.5 mg, 0.005 mmol), and dioxane (0.8 mL) were added sequentially to a 15 mL pressure-resistant tube equipped with a stir bar. The cap was tightened, and the pressure-resistant tube was placed in a metal module and reacted at 165 °C for 16 hours. After the reaction was complete, the tube was cooled in an ice-water bath, the cap was carefully opened, and the reaction products were quantitatively analyzed by gas chromatography (GC), and the yield was calculated. The compounds I and II used in Examples 4–22 are detailed in Table 1, as are the products and yields of the dehydrogenation coupling reaction.

[0086] Table 1. Compounds I and II used in Examples 4-22, along with their products and yields.

[0087]

[0088]

[0089]

[0090]

[0091] As can be seen from Examples 1-23 above, catalyst [Mn]-1 exhibits excellent substrate applicability in the dehydrogenation coupling reaction of 1H-indole and benzyl alcohol with different substituents on the benzene ring. The position of the substituent on the indole does not significantly affect the reaction results; for example, the dehydrogenation coupling reaction with phenylethanol can proceed smoothly using indoles substituted at positions 2, 4, 5, and 6. Furthermore, it is well compatible with substituents on the benzene ring of benzyl alcohol derivatives with different electronic effects and steric hindrance effects. NMR data of the reaction products in some examples are as follows:

[0092] Example 4: 1 H NMR (400MHz, CDCl3) δ7.79 (s, 1H), 7.44 (d, J = 8.0Hz, 1H), 7.25 (d, J = 8.1Hz, 1H), 7.1 2–7.07(m,3H),7.01–6.97(m,2H),6.80(d,J=2.3Hz,1H),3.99(s,2H),2.23(s,3H). 13 C NMR (101MHz, CDCl3) δ138.16,136.48,135.32,129.05,128.59,127.52,122.28,122.03,119.35,119.21,116.13,111.07,31.18,21.06.

[0093] Example 5: 1 H NMR (400MHz, CDCl3) δ7.79(s,1H),7.43(d,J=7.9Hz,1H),7.23(d,J=8.1Hz,1H),7 .13–7.07(m,3H),7.01–6.97(m,1H),6.77–6.72(m,3H),3.97(s,2H),3.68(s,3H). 13 C NMR (101MHz, CDCl3) δ157.85,136.52,133.37,129.64,127.47,122.27,122.05,119.35,119.21,116.30,113.79,111.11,55.31,30.75.

[0094] Example 6: 1 H NMR (400MHz, CDCl3) δ7.74(s,1H),7.46(dd,J=7.9,1.0Hz,1H),7.23(dd,J=8.1,1.0Hz,1H),7. 16–6.94(m,6H),6.82–6.72(m,1H),3.99(s,2H),2.78(p,J=6.9Hz,1H),1.14(d,J=6.9Hz,6H). 13 C NMR (101MHz, CDCl3) δ146.42,138.60,136.49,128.61,127.59,126.42,122.34,122.04,119.36,119.24,116.09,111.10,33.75,31.16,24.14.

[0095] Example 7: 1 H NMR (400MHz, DMSO-d6) δ10.87(s,1H),7.61(d,J=7.1Hz,2H),7.55(d,J=8.1Hz,2H),7.47–7.41(m,3H) ,7.38–7.30(m,4H),7.20(d,J=2.3Hz,1H),7.05(t,J=7.6Hz,1H),6.93(t,J=8.0Hz,1H),4.08(s,2H). 13C NMR(101MHz,DMSO-d6)δ141.64,140.59,138.04,136.90,129.44,129.33,127.59, 127.46,126.97,126.94,123.65,121.42,119.01,118.76,114.16,111.88,31.11.

[0096] Example 8: 1 H NMR(400MHz, CDCl3) δ7.83(s,1H),7.38(dd,J=7.9,1.1Hz,1H),7.26(dd,J=8.1,0 .9Hz,1H),7.16–7.10(m,5H),7.02–6.98(m,1H),6.81–6.80(m,1H),3.99(s,2H). 13 C NMR (101MHz, CDCl3) δ139.71,136.50,131.62,130.04,128.45,127.30,122.40,122.22,119.51,119.08,115.28,111.18,31.02.

[0097] Example 9: 1 H NMR(400MHz, CDCl3)δ7.82(s,1H),7.47(s,1H),7.40–7.33(m,3H),7.28–7.24(m ,2H),7.13–7.09(m,1H),7.02–6.98(m,1H),6.80(d,J=2.4Hz,1H),4.06(s,2H). 13 C NMR (101MHz, CDCl3) δ142.20,136.50,132.10,131.11,130.79,130.48,130.16,128.80,127.26,125.71,125.46,125.43,1 25.39,125.35,123.00,122.95,122.91,122.87,122.84,122.51,122.31,120.30,119.61,118.97,114.84,111.24,31.49.

[0098] Example 10: 1H NMR (400MHz, CDCl3) δ7.83 (s, 1H), 7.40 (dt, J = 7.9, 1.2Hz, 1H), 7.26 (d, J = 8.1 Hz,1H),7.16–7.09(m,2H),7.03–6.97(m,2H),6.89–6.77(m,3H),4.02(s,2H). 13 CNMR (101MHz, CDCl3) δ164.25,161.81,143.98,143.91,136.48,129.75,129.67,127.33,124.33,124 .30,122.46,122.22,119.53,119.08,115.64,115.43,114.99,112.93,112.72,111.19,31.40,31.38.

[0099] Example 11: 1 H NMR(400MHz, CDCl3)δ7.65(s,1H),7.44(dd,J=8.0,2.5Hz,1H),7.19(d,J=8.1Hz,1H),7.12–7.04(m, 2H),7.04–6.95(m,3H),6.95–6.86(m,1H),6.73(d,J=2.1Hz,1H),3.97(d,J=2.2Hz,2H),2.20(s,3H). 13 C NMR (101MHz, CDCl3) δ141.26,137.96,136.50,129.57,128.32,127.58,126. 74,125.84,122.42,122.08,119.42,119.25,115.97,111.15,31.59,21.53.

[0100] Example 12: 1 H NMR (400MHz, CDCl3) δ7.83 (s, 1H), 7.49 (d, J = 7.9Hz, 1H), 7.28 (dd, J = 8.1, 1.0Hz ,1H),7.16–6.98(m,6H),6.64(dd,J=2.3,1.1Hz,1H),4.00(s,2H),2.25(s,3H). 13 C NMR (101MHz, CDCl3) δ139.08,136.46,130.12,129.41,127.58,126.18,125.94,122.38,122.05,119.34,119.07,115.25,111.07,29.26,19.51.

[0101] Example 13: 1 H NMR (400MHz, CDCl3) δ8.53(s,1H),8.42–8.37(m,2H),7.46(d,J=7.8Hz,1H),7.40(d,J=7.9Hz,1H),7. 26(d,J=8.1Hz,1H),7.10(t,J=7.6Hz,2H),7.00(t,J=7.5Hz,1H),6.83(d,J=2.2Hz,1H),4.02(s,2H). 13 C NMR (101MHz, CDCl3) δ150.05,147.40,136.78,136.58,136.29,127.13,123.46,122.60,122.22,119.51,118.88,114.36,111.32,28.90.

[0102] Example 14: 1 H NMR (400MHz, CDCl3) δ7.72 (s, 1H), 7.23–7.08 (m, 13H), 6.89 (t, J = 7.5Hz, 1H), 6.43 (d, J = 2.3Hz, 1H), 5.57 (s, 1H). 13 C NMR (101MHz, CDCl3) δ144.00,136.75,129.08,128.35,127.05,126.30,124.13,122.16,119.98,119.96,119.46,111.11,48.89.

[0103] Example 15: 1 H NMR (400MHz, CDCl3) δ7.63(s,1H),7.25–7.15(m,5H),7.12(d,J=8.0Hz,2H),6.92(d,J=8.3Hz,1H),6.72(d,J=2.3Hz,1H),3.99(s,2H),2.33(s,3H). 13 CNMR(101MHz, CDCl3)δ141.40,134.81,128.74,128.64,128.39,127.78,125.90,123.72,122.60,118.79,115.30,110.81,31.58,21.59.

[0104] Example 16: 1H NMR (400MHz, CDCl3) δ7.68 (s, 1H), 7.21–7.16 (m, 4H), 7.10 (dd, J = 8.7, 3.2Hz, 2H), 6.8 6(d,J=2.4Hz,1H),6.76(d,J=2.5Hz,2H),6.75–6.73(m,2H),3.98(s,2H),3.70(s,3H). 13 C NMR (101MHz, CDCl3) δ153.96,141.22,131.66,128.75,128.40,127.92,125.95,123.28,115.53,112.18,111.86,101.11,55.95,31.67.

[0105] Example 17: 1 H NMR (400MHz, CDCl3) δ7.77 (s, 1H), 7.21–7.03 (m, 7H), 6.84 (q, J = 4.0, 3.1Hz, 2H), 3.96 (s, 2H). 13 C NMR (101MHz, CDCl3) δ158.92, 156.60, 140.86, 132.98, 128.57 (d, J = 20.9Hz), 127.87 (d, J = 9.5Hz), 126.0 8, 124.18, 116.02 (d, J = 4.6Hz), 111.72 (d, J = 9.6Hz), 110.45 (d, J = 26.4Hz), 104.12 (d, J = 23.3Hz), 31.60.

[0106] Example 18: 1 H NMR (400MHz, CDCl3) δ7.83(s,1H),7.56(d,J=1.8Hz,1H),7.22–7.10(m,7H),6.80(d,J=2.3Hz,1H),3.97(s,2H). 13 C NMR (101MHz, CDCl3) δ140.71,135.06,129.27,128.64,128.48,126.11,124.95,123.62,121.75,115.60,112.72,112.57,31.40.

[0107] Example 19: 1H NMR (400MHz, CDCl3) δ7.87(s,1H),7.45(d,J=7.9Hz,1H),7.28(d,J=8.1Hz,1H),7.21– 7.18(m,4H),7.13–7.09(m,2H),7.02–6.98(m,1H),6.84(d,J=2.3Hz,1H),4.05(s,2H). 13 C NMR(101MHz, CDCl3)δ141.20,136.46,128.70,128.33,127.48,125.88,122.32,122.06,119.38,119.17,115.88,111.06,31.61.HRMS(ESI)calcd.forC 15 H 13 IN[M+H] + 334.00872, found 334.00829.

[0108] Example 20: 1 H NMR(400MHz, CDCl3)δ7.63(s,1H),7.31(d,J=7.8Hz,1H),7.20–7.11(m,5H) ,7.09–6.99(m,2H),6.94(td,J=7.5,1.1Hz,1H),3.98(s,2H),2.28(s,3H). 13 C NMR (101MHz, CDCl3) δ141.68,135.31,131.66,130.38,128.94,128.30,125.69,121.02,119.28,118.41,110.59,110.15,30.13,11.83.

[0109] Example 21: 1 H NMR (400MHz, CDCl3) δ8.04(s,1H),7.46–7.44(m,2H),7.39–7.32(m,5H),7.20–7.13(m,5H),7.01-6.97(m,1H),4.21(s,2H). 13 C NMR (101MHz, CDCl3) δ141.49,136.04,135.44,132.94,128.92,128.40,128.24,1 27.85,127.78,125.80,125.18,122.42,119.81,119.66,111.20,110.77,30.45.

[0110] Example 22:1 H NMR (400MHz, CDCl3) δ7.84 (s, 1H), 7.25–7.10 (m, 7H), 6.90 (t, J = 7.9Hz, 1H), 6.63 (d, J = 2.4Hz, 1H), 4.34 (s, 2H). 13 C NMR(101MHz, CDCl3)δ141.63,137.73,129.00,128.35,125.88,125.60,124.55,124.03,122.96,116.92,114.54,110.54,32.58.HRMS(ESI)calcd.for C 15 H 13 BrN[M+H] + 286.02259, found 286.02293.

[0111] Example 23: 1 H NMR (400MHz, CDCl3) δ7.85–7.75(m,1H),7.40(d,J=1.7Hz,1H),7.26(d,J=8.4Hz ,1H),7.23–7.14(m,4H),7.15–7.02(m,2H),6.80(d,J=2.3Hz,1H),4.00(s,2H). 13 C NMR(101MHz, CDCl3)δ140.82,137.24,128.63,128.43,126.40,126.07,122.94,122.71,120.47,116.06,115.67,114.01,31.48.HRMS(ESI)calcd.for C 15 H 13 BrN[M+H] + 286.02259, found 286.02286.

[0112] Examples 24-34

[0113] The application of the Pincer-type PNP manganese complex catalysts in the dehydrogenation coupling reaction of compounds I and II, as described in Examples 24-34, includes the following steps:

[0114] In a glove box, 1H-indole (29 mg, 0.25 mmol), benzyl alcohol (54 mg, 0.5 mmol), a base, [Mn]-1 catalyst (2.5 mg, 0.005 mmol), and an organic solvent were added sequentially to a 15 mL pressure-resistant tube equipped with a stir bar. The cap was tightened, and the pressure-resistant tube was placed in a metal module and reacted at the set temperature for 16 hours. After the reaction was complete, the tube was cooled in an ice-water bath, the cap was carefully opened, and the reaction products were quantitatively analyzed by gas chromatography (GC), and the yield was calculated. The base and its amount, organic solvent and its amount, set reaction temperature, and product yield used in Examples 24–34 are shown in Table 2.

[0115] Table 2 shows the base and its amount, organic solvent and its amount, reaction temperature, and product yield used in Examples 24-34.

[0116]

[0117]

[0118] As can be seen from Table 2 above, the reaction temperature, the type and amount of alkali, and the type and amount of solvent all have a significant impact on the reaction effect. Specifically, this is reflected in the following:

[0119] 1) Under the same conditions, potassium hydroxide reacts better as an alkali than potassium tert-butoxide, sodium tert-butoxide, sodium ethoxide and potassium carbonate (Comparative Examples 1, 26-29).

[0120] 2) Under the same conditions, the yield of 1.2 equiv. of base (0.3 mol) was much higher than that of 1.0 equiv. of base (0.25 mol) and similar to that of 1.4 equiv. of base (0.35 mol) (Comparative Examples 1, 24, 25).

[0121] 3) Under the same conditions, the reaction was carried out in dioxane to obtain the highest yield (comparative Examples 1, 30, and 31).

[0122] 4) Under the same conditions, decreasing or increasing the amount of solvent from 0.8 mL to 0.5 mL and 1.2 mL will reduce the yield (compare Examples 1, 32, and 33).

[0123] 6) Under the same conditions, lowering the reaction temperature from 165°C to 140°C will reduce the yield (Comparative Examples 1 and 34).

[0124] Comparative Example 1

[0125] The dehydrogenation coupling reaction of compounds I and II in this comparative example differs from that in Example 1 only in that the catalyst [Mn]-1 in Example 1 is replaced with catalyst [Mn]-4, and the yield is trace (<1%).

[0126] Comparative Example 2

[0127] The dehydrogenation coupling reactions of compounds I and II in this comparative example differ from those in Example 1 only in that the catalyst [Mn]-1 in Example 1 is replaced with catalyst [Mn]-5, with a yield of 17%.

[0128] Comparative Example 3

[0129] The dehydrogenation coupling reactions of compounds I and II in this comparative example differ from those in Example 1 only in that the catalyst [Mn]-1 in Example 1 is replaced with catalyst [Mn]-6, with a yield of 13%.

[0130] Comparing Examples 1-3 and Comparative Examples 1-3, it was found that, using 1H-indole and benzyl alcohol as model substrates, catalysts [Mn]-1, [Mn]-2, and [Mn]-3 all exhibited excellent reaction performance, with [Mn]-1 as the catalyst yielding the 1H-indole C3-benzylated product in 99% yield. In contrast, NNP-type pincer-shaped manganese catalysts [Mn]-4, [Mn]-5, and [Mn]-6 only yielded lower conversion rates (<20%). This indicates that PNP-type pincer-shaped manganese catalysts have higher reactivity than NNP-type pincer-shaped manganese catalysts.

[0131] Example 35

[0132] The application of the Pincer-type PNP manganese complex catalyst in the dehydrogenation coupling reaction of compound I and compound II in this embodiment, where compound I is phenylethanol and compound II is 1H-indole, includes the following steps:

[0133] In a glove box, 1H-indole (29 mg, 0.25 mmol), phenylethanol (61 mg, 0.5 mmol), potassium hydroxide (16.8 mg, 0.3 mmol), catalyst [Mn]-1 (2.5 mg, 0.005 mmol), and dioxane (0.8 mL) were added sequentially to a 15 mL pressure-resistant tube equipped with a stir bar. The cap was tightened, and the pressure-resistant tube was placed in a metal module and reacted at 165 °C for 16 hours. After the reaction was complete, the tube was cooled in an ice-water bath. The cap was carefully opened, and the reaction product was quantitatively analyzed by gas chromatography (GC). The yield was calculated to be 90%.

[0134] MRI: 1H NMR (400MHz, DMSO-d6) δ11.33(s,1H),8.01(d,J=7.7Hz,1H),7.65(d,J=2.6Hz,1H), 7.58(d,J=7.0Hz,2H),7.45–7.41(m,2H),7.34(t,J=7.7Hz,2H),7.20–7.08(m,4H). 13 C NMR (101MHz, DMSO-d6) δ139.03,137.49,129.07,126.67,126.53,125.89,125.62,123.74,123.01,122.23,120.30,120.13,114.13,112.37.

[0135] The chemical reactions involved are:

[0136]

[0137] Example 36

[0138] The application of the Pincer-type PNP manganese complex catalyst in the dehydrogenation coupling reaction of compounds I and II in this embodiment differs from that in Example 35 only in that catalyst [Mn]-1 in Example 35 is replaced with catalyst [Mn]-2, with a yield of 82%.

[0139] Example 37

[0140] The application of the Pincer-type PNP manganese complex catalyst in the dehydrogenation coupling reaction of compounds I and II in this embodiment differs from that in Example 35 only in that catalyst [Mn]-1 in Example 35 is replaced with catalyst [Mn]-3, with a yield of 75%.

[0141] Examples 38-57

[0142] The application of the Pincer-type PNP manganese complex catalysts in Examples 38-57 in the dehydrogenation coupling reaction of compounds I and II includes the following steps:

[0143] In a glove box, compound II (0.25 mmol), compound I (0.5 mmol), potassium hydroxide (16.8 mg, 0.3 mmol), catalyst [Mn]-1 (2.5 mg, 0.005 mmol), and dioxane (0.8 mL) were added sequentially to a 15 mL pressure-resistant tube equipped with a stir bar. The cap was tightened, and the pressure-resistant tube was placed in a metal module and reacted at 165 °C for 16 hours. After the reaction was complete, the tube was cooled in an ice-water bath, the cap was carefully opened, and the reaction products were quantitatively analyzed by gas chromatography (GC), and the yield was calculated. The compounds I, II, reaction products, and yields used in Examples 38–57 are shown in Table 3.

[0144] Table 3. Compound I, Compound II, reaction products, and yields used in Examples 38-57

[0145]

[0146]

[0147]

[0148]

[0149]

[0150] As shown in Table 3 above, catalyst [Mn]-1 exhibits excellent substrate applicability in the dehydrogenation coupling reaction of indole and phenethyl alcohol with different substituents. The position of the substituent in the indole does not significantly affect the reaction results; for example, the dehydrogenation coupling reaction with phenethyl alcohol can proceed smoothly using indoles substituted at positions 4, 5, 6, and 7. Furthermore, it is well compatible with substituents on the benzene ring of aryl ethanol that exhibit different electronic and steric effects.

[0151] As can be seen from Table 3 above, catalyst [Mn]-1 can catalyze the dehydrogenation coupling reaction of indole and phenylethanol with different substituents to synthesize C3-alkenylated indole compounds. It can also yield alkenylated products in moderate yields (>50%) for aliphatic alcohols with different carbon chain lengths. For example, propanol, butanol, pentanol, hexanol, and heptanol can all undergo successful dehydrogenation conversion in this reaction system to obtain the target products.

[0152] NMR data of the reaction products in some examples:

[0153] Example 38: 1<1H> NMR (400 MHz, DMSO-d6) δ 11.29 (s, 1H), 7.99 (d, J = 7.8 Hz, 1H), 7.62 (d, J = 2.6 Hz, 1H), 7.46 (d, J = 7.9 Hz, 2H), 7.42 (d, J = 7.4 Hz, 1H), 7.36 (d, J = 16.6 Hz, 1H), 7.18–7.09 (m, 4H), 7.06 (d, J = 16.6 Hz, 1H), 2.30 (s, 3H). 13 <13C> NMR (101 MHz, DMSO) δ 137.47, 136.22, 135.83, 129.67, 126.15, 125.83, 125.63, 123.77, 122.16, 121.98, 120.27, 120.05, 114.21, 112.34, 21.25.

[0154] Example 39: 1 <1H> NMR (400 MHz, DMSO-d6) δ 11.26 (s, 1H), 7.98 (d, J = 7.8 Hz, 1H), 7.59 (d, J = 2.5 Hz, 1H), 7.51 (d, J = 8.4 Hz, 2H), 7.41 (d, J = 8.6 Hz, 1H), 7.27 (d, J = 16.6 Hz, 1H), 7.17–7.03 (m, 3H), 6.92 (d, J = 8.3 Hz, 2H), 3.76 (s, 3H). 13 <13C> NMR (101 MHz, DMSO) δ 158.46, 137.44, 131.69, 127.07, 125.72, 125.63, 123.59, 122.11, 120.78, 120.26, 119.95, 114.56, 114.34, 112.30, 55.55.

[0155] Example 40: 1 <1H> NMR (400 MHz, DMSO-d6) δ 11.33 (s, 1H), 8.01 (d, J = 8.0 Hz, 1H), 7.64–7.60 (m, 3H), 7.43 (d, J = 7.5 Hz, 1H), 7.38 (d, J = 16.6 Hz, 1H), 7.21–7.08 (m, 5H). 13C NMR (101MHz, DMSO) δ161.33 (d, J = 242.8Hz), 137.48, 135.63 (d, J = 3.0Hz), 127.56 (d, J = 7.7Hz), 1 26.45,125.59,122.97,122.59,122.23,120.32,120.11,115.85(d,J=21.2Hz),114.06,112.37.

[0156] Example 42: 1 H NMR(400MHz,DMSO-d6)δ11.37(s,1H),8.01(d,J=7.8Hz,1H),7.66(s,1H),7.55–7.50(m,4H ),7.47(d,J=16.6Hz,1H),7.43(d,J=7.9Hz,1H),7.19–7.12(m,2H),7.07(d,J=16.7Hz,1H). 13 C NMR (101MHz, DMSO) δ138.43,137.52,131.88,127.84,126.98,125.56,124.07,122.31,120.37,120.23,119.20,113.98,112.41.

[0157] Example 44: 1 H NMR (400MHz, DMSO-d6) δ11.34(s,1H),7.95(d,J=7.1Hz,1H),7.68–7.65(m,2H),7.44(d,J= 7.4Hz,1H),7.32(d,J=16.4Hz,1H),7.23(d,J=13.6Hz,1H),7.21–7.09(m,5H),2.42(s,3H). 13 C NMR (101MHz, DMSO) δ137.63,137.51,134.77,130.73,126.67,126.61,125.6 0,124.44,124.10,122.22,121.24,120.24,120.10,114.49,112.42,20.16.

[0158] Example 45: 1¹H NMR (400 MHz, DMSO-d₆) δ 11.32 (s, 1H), 8.00 (d, J=7.7 Hz, 1H), 7.64 (d, J=2.6 Hz, 1H), 7.43 (s, 1H), 7.42–7.39 (m, 2H), 7.36 (d, J=7.9 Hz, 1H), 7.23 (t, J=7.6 Hz, 1H), 7.18–7.09 (m, 2H), 7.06 (d, J=16.6 Hz, 1H), 7.00 (d, J=7.6 Hz, 1H), 2.33 (s, 3H). 13 ¹³C NMR (101 MHz, DMSO) δ 138.93, 138.02, 137.49, 128.95, 127.41, 126.46, 126.43, 125.62, 123.83, 123.17, 122.80, 122.21, 120.29, 120.11, 114.17, 112.36, 21.57.

[0159] Example 46: 1 ¹H NMR (400 MHz, DMSO-d₆) δ 11.38 (s, 1H), 8.08 (d, J=7.1 Hz, 1H), 7.97 (s, 1H), 7.88 (s, 3H), 7.86 (s, 1H), 7.71 (d, J=2.6 Hz, 1H), 7.60 (d, J=16.6 Hz, 1H), 7.51–7.41 (m, 3H), 7.28 (d, J=16.6 Hz, 1H), 7.21–7.13 (m, 2H). 13 ¹³C NMR (101 MHz, DMSO) δ 137.54, 136.71, 134.04, 132.44, 128.48, 128.02, 126.77, 126.72, 125.72, 125.65, 124.94, 123.78, 123.75, 123.69, 122.29, 120.37, 120.21, 114.26, 112.43.

[0160] Example 47: 1 ¹H NMR (400 MHz, DMSO-d₆) δ 11.40 (s, 1H), 8.76 (d, J=2.2 Hz, 1H), 8.38 (d, J=4.7 Hz, 1H), 8.03 (dd, J=13.8, 7.8 Hz, 2H), 7.69 (d, J=2.7 Hz, 1H), 7.56 (d, J=16.6 Hz, 1H), 7.44 (d, J=7.8 Hz, 1H), 7.36 (dd, J=8.0, 4.6 Hz, 1H), 7.20–7.09 (m, 3H). 13CNMR(101MHz,DMSO)δ147.94,147.48,137.52,134.75,131.91,127.19,125.54,125.13,124.13,122.36,120.39,120.29,119.90,113.99,112.44.

[0161] Example 48: 1 H NMR (400MHz, DMSO-d6) δ11.34(s,1H),7.95(d,J=7.8Hz,1H),7.64(d,J=2.6Hz,1H),7.42(d,J=7.9Hz ,1H),7.33(d,J=5.1Hz,1H),7.29(d,J=16.3Hz,1H),7.18–7.09(m,4H),7.02(dd,J=5.1,3.5Hz,1H). 13 C NMR (101MHz, DMSO-d6) δ144.54,137.53,128.25,126.87,125.36,124.76,123.49,122.76,122.30,120.27,120.20,117.56,113.64,112.42.

[0162] Example 54: 1 H NMR (400MHz, DMSO-d6): δ (ppm) 11.06 (br s,1H),7.76(d,J=7.8Hz,1H),7.38-7.36(m,2H),7.10(t,J=7.4Hz,1H),7.03(t,J=7.4Hz,1H), 6.53(d,J=16.0Hz,1H),6.15(dt,J=16.0,6.5Hz,1H),2.25-2.18(m,2H),1.08(t,J=7.4Hz,3H). 13 C NMR (100MHz, DMSO-d6): δ (ppm) 136.77, 127.31, 125.21, 123.86, 122.08, 121.32, 119.39, 119.13, 113.52, 111.65, 26.09, 14.20.

[0163] Examples 58-68

[0164] The application of the Pincer-type PNP manganese complex catalyst in the dehydrogenation coupling reaction of compounds I and II, as described in Examples 58-68, includes the following steps:

[0165] In a glove box, 1H-indole (29 mg, 0.25 mmol), phenylethanol (61 mg, 0.5 mmol), a base, [Mn]-1 catalyst (2.5 mg, 0.005 mmol), and an organic solvent were added sequentially to a 15 mL pressure-resistant tube equipped with a stir bar. The cap was tightened, and the pressure-resistant tube was placed in a metal module and reacted at the set temperature for 16 hours. After the reaction was complete, the tube was cooled in an ice-water bath, the cap was carefully opened, and the reaction products were quantitatively analyzed by gas chromatography (GC), and the yield was calculated. The base and its amount, organic solvent and its amount, set reaction temperature, and product yield used in Examples 58–68 are shown in Table 4.

[0166] Table 4. Examples 58-68: alkali and its dosage, organic solvent and its dosage, set reaction temperature, and product yield.

[0167]

[0168]

[0169] As can be seen from the table above, the reaction temperature, the type and amount of alkali, and the type and amount of solvent all have a significant impact on the reaction results. Specifically, this is reflected in the following:

[0170] 1) Under the same conditions, potassium hydroxide reacts better as an alkali than potassium tert-butoxide, sodium tert-butoxide, sodium ethoxide and potassium carbonate (compare Examples 34, 60-63).

[0171] 2) Under the same conditions, the yield of 1.2 equiv. of base (0.3 mol) was much higher than that of 1.0 equiv. of base (0.25 mol) and similar to that of 1.4 equiv. of base (0.35 mol) (Comparative Examples 43, 58, 59).

[0172] 3) Under the same conditions, the reaction was carried out in dioxane to obtain the highest yield (comparative examples 34, 64, and 65).

[0173] 4) Under the same conditions, decreasing or increasing the amount of solvent from 0.8 mL to 0.5 mL and 1.2 mL will reduce the yield (compare Examples 34, 66, and 67).

[0174] 6) Under the same conditions, lowering the reaction temperature from 165°C to 140°C will reduce the yield (Comparative Examples 34 and 68).

[0175] Comparative Example 4

[0176] The application of compounds I and II in the dehydrogenation coupling reaction of this embodiment differs from that of Example 35 only in that the catalyst [Mn]-1 in Example 35 is replaced with catalyst [Mn]-4, and the yield is trace (<1%).

[0177] Comparative Example 5

[0178] The application of compounds I and II in the dehydrogenation coupling reaction of this embodiment differs from that of Example 35 only in that the catalyst [Mn]-1 in Example 35 is replaced with catalyst [Mn]-5, with a yield of 5%.

[0179] Comparative Example 6

[0180] The application of compounds I and II in the dehydrogenation coupling reaction of this embodiment differs from that of Example 35 only in that the catalyst [Mn]-1 in Example 35 is replaced with catalyst [Mn]-6, with a yield of 9%.

[0181] Comparative Examples 35-37 and Comparative Examples 4-6 show that, using 1H-indole and phenylethanol as model substrates, catalysts [Mn]-1, [Mn]-2, and [Mn]-3 all exhibit excellent reaction performance, with [Mn]-1 achieving a 90% yield of the 1H-indole C3-alkenylated product. In contrast, NNP-type pincer-shaped manganese catalysts [Mn]-4, [Mn]-5, and [Mn]-6 only yielded lower conversion rates (<10%). This indicates that PNP-type pincer-shaped manganese catalysts have higher reactivity than NNP-type pincer-shaped manganese catalysts.

Claims

1. Application of Pincer-type PNP manganese complex catalyst in the dehydrogenation coupling reaction of compound I and compound II, wherein compound I is selected from one of the following compounds: Compound II is selected from one of the following compounds: The dehydrogenation coupling reaction is carried out by reacting compound I and compound II in an organic solvent under the action of a base and the catalyst of the Pincer type PNP manganese complex, at 165°C and under closed conditions for ≥6h. The amount of base used for each 0.25mmol compound II is 0.3~0.35mmol, and the volume of organic solvent used is 0.8mL. The base is potassium hydroxide, and the organic solvent is one or any combination of dioxane, toluene, and tetrahydrofuran. The molar ratio of compound I to compound II is ≥2:1; The structure of the Pincer-type PNP manganese complex catalyst is shown in Formula II: ； In formula II, R 3 is -H, X is -Br, and R2is one of isopropyl or cyclohexyl. The product of the dehydrogenation coupling reaction is selected from one of the following compounds: 。

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