Method for selectively preparing imidazo [1, 2-a] pyridine derivative by synergistically regulating rhodium catalysis through solvent and basic salt

Abstract

The invention discloses a method for selectively preparing an imidazo [1, 2-a] pyridine derivative by synergistically regulating rhodium catalysis through a solvent and alkali salt, which comprises the following steps: taking 2-aryl imidazo [1, 2-a] pyridine or substituted 2-aryl imidazo [1, 2-a] pyridine and alpha-chloro-aryl ethyl ketone or substituted alpha-chloro-aryl ethyl ketone as initial raw materials; the metal rhodium catalyst is used for catalyzing the carbon-hydrogen bond activation reaction to prepare the imidazo [1, 2-a] pyridine derivative, the reaction condition is mild, the selectivity and yield are high, the safety is high, and industrial production is facilitated; according to the invention, 2-aryl imidazo [1, 2-a] pyridine or substituted 2-aryl imidazo [1, 2-a] pyridine and alpha-chloro-aryl ethyl ketone or substituted alpha-chloro-aryl ethyl ketone are used as initial raw materials for the first time, a reaction is regulated and controlled by simultaneously adjusting a solvent and basic salt, and a formyl methyl imidazo [1, 2-a] pyridine compound or 6-aryl naphtho [1 ', 2': 4, 5-difluoro-2-pyridine-2-one or 6-aryl naphtho [1 ', 2': 4, 5-difluoro-2-pyridine-2-one is prepared from the same initial raw materials. According to the invention, different products of the 5, 5] imidazo [1, 2-a] pyridine compound are synthesized, and the application universality is increased.

Description

Technical Field

[0001] This invention relates to the field of chemical synthesis technology, and in particular to a method for the selective preparation of imidazo[1,2-a]pyridine derivatives by rhodium catalysis synergistically controlled by solvent and basic salt. Background Technology

[0002] Imidazolo[1,2-a]pyridine compounds are extremely important nitrogen-containing heterocyclic compounds, whose skeletons are widely found in natural products, bioactive molecules, and drug molecules. These compounds are also key intermediates in the synthesis of pharmaceutical and functional materials. Therefore, the preparation methods and applications of these compounds have attracted great attention from chemists. However, their synthetic methods are currently limited. α-chloroaryl ketones, as important coupling reagents, have been reported in the synthesis of acylated and nitrogen-containing heterocyclic compounds. However, their synthesis has certain drawbacks, such as harsh reaction conditions, cumbersome synthetic steps, or the synthesis of only one product from the same starting materials—either an acylated or cyclized product. These shortcomings limit their widespread application in the synthetic field. Summary of the Invention

[0003] Therefore, based on the above background, this invention provides a method for the selective preparation of imidazo[1,2-a]pyridine derivatives by synergistic regulation of solvent and basic salt using rhodium catalysis. This invention uses 2-arylimidazo[1,2-a]pyridine or substituted 2-arylimidazo[1,2-a]pyridine, α-chloroaryl ethyl ketone or substituted α-chloroaryl ethyl ketone as starting materials, and uses a rhodium catalyst to catalyze the carbon-hydrogen bond activation reaction. The reaction conditions are simple and mild, facilitating industrial production. Furthermore, the reaction can be regulated by simultaneously adjusting the solvent and basic salt, allowing the preparation of formylmethylimidazo[1,2-a]pyridine compounds or 6-arylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine compounds from the same starting materials, thus increasing their applicability.

[0004] The technical solution provided by this invention is as follows:

[0005] A method for selectively preparing imidazo[1,2-a]pyridine derivatives by synergistic regulation of solvent and basic salt using rhodium catalysis involves using compounds A and B as starting materials under heating conditions, and using a rhodium catalyst to catalyze the carbon-hydrogen bond activation reaction. By simultaneously adjusting the types of solvent and basic salt, formylmethylimidazo[1,2-a]pyridine compounds or 6-arylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine compounds can be selectively prepared.

[0006] The compound A is 2-arylimidazo[1,2-a]pyridine or substituted 2-arylimidazo[1,2-a]pyridine;

[0007] The compound B is α-chloroaryl ethyl ketone or substituted α-chloroaryl ethyl ketone;

[0008] The solvent for selectively preparing formylmethylimidazo[1,2-a]pyridine compounds is selected from at least one of tetrahydrofuran, 1,4-dioxane or p-xylene, and the basic salt is selected from acetate.

[0009] The solvent for selectively preparing 6-arylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine compounds is selected from at least one of trifluoroethanol, hexafluoroisopropanol or methanol, and the basic salt is selected from carbonates;

[0010] The structural formula of the formylmethylimidazo[1,2-a]pyridine compound is shown in the following formula (I):

[0011]

[0012] The structural formula of the 6-arylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine compound is shown in Formula (II) below.

[0013]

[0014] In formulas (I) and (II), R1, R2, and R3 are each independently selected from one of hydrogen, alkyl, halogen, ester, and trifluoromethyl groups.

[0015] Furthermore, the rhodium catalyst is selected from at least one of dichloro(pentamethylcyclopentadienyl)rhodium(III) dimer, rhodium hexafluoroantimonylic acid (triacetonitrile-pentamethylcyclopentadienyl) and rhodium pentamethylcyclopentadienyl acetate.

[0016] Furthermore, the acetate is selected from at least one of sodium acetate or cesium acetate.

[0017] Furthermore, the carbonate is selected from at least one of sodium carbonate or lithium carbonate.

[0018] Further, the substituted 2-arylimidazo[1,2-a]pyridine is a benzene ring of 2-arylimidazo[1,2-a]pyridine in which at least one of the para or meta positions is substituted; the substituted α-chloroaryl ethyl ketone is a benzene ring of α-chloroaryl ethyl ketone in which at least one of the para or meta positions is substituted.

[0019] The substituent is selected from one of alkyl, halogen, ester, or trifluoromethyl groups.

[0020] Furthermore, the molecular formula of the 2-arylimidazo[1,2-a]pyridine or the substituted α-chloroaryl ethyl ketone is shown in formula (III):

[0021]

[0022] The molecular formula of the α-chloroaryl ethyl ketone or substituted α-chloroaryl ethyl ketone is shown in formula (IV) below:

[0023]

[0024]

[0025] In formulas (III) and (IV), R1, R2, and R3 are each independently selected from one of hydrogen, alkyl, halogen, ester, or trifluoromethyl.

[0026] Furthermore, the formylmethylimidazo[1,2-a]pyridine compound with the structural formula of formula (1) specifically includes any of the following compounds:

[0027]

[0028] Furthermore, the 6-arylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine compounds with the structural formula of formula (II) specifically include any of the following compounds:

[0029]

[0030] Furthermore, it specifically includes the following steps:

[0031] 1) Disperse 2-arylimidazo[1,2-a]pyridine or substituted 2-arylimidazo[1,2-a]pyridine, α-chloroaryl ethyl ketone or substituted α-chloroaryl ethyl ketone in a solvent;

[0032] 2) Stir the reaction at a temperature of 80-100℃, and then separate the reacted materials.

[0033] Furthermore, the molar ratio of 2-arylimidazo[1,2-a]pyridine or substituted 2-arylimidazo[1,2-a]pyridine, α-chloroaryl ethyl ketone or substituted α-chloroaryl ethyl ketone to the rhodium catalyst is 1:(0.01~1):0.1;

[0034] The molar ratio of 2-arylimidazo[1,2-a]pyridine or substituted 2-arylimidazo[1,2-a]pyridine to a basic salt is 1:(1-3);

[0035] Furthermore, in step 2), material separation may be performed using methods such as recrystallization or column chromatography. Solvents used in recrystallization include acetone, ethyl acetate, ethanol, isopropanol, n-hexane, tetrahydrofuran, and dichloromethane. When using column chromatography for product separation, silica gel or alumina is used as the stationary phase, and a mixture of polar and non-polar solvents is selected as the developing solvent, such as dichloromethane-petroleum ether, ethyl acetate-petroleum ether, ethyl acetate-n-hexane, or dichloromethane-acetone.

[0036] The synthetic route of this invention is as follows:

[0037]

[0038] Based on the same inventive concept, this invention also provides the application of formylmethylimidazo[1,2-a]pyridine compounds or 6-arylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine compounds prepared by the method of solvent and basic salt synergistic regulation of rhodium catalysis for selective preparation of imidazo[1,2-a]pyridine derivatives in the preparation of pharmaceuticals or organic optoelectronic materials.

[0039] The beneficial effects achieved by this invention are as follows:

[0040] This invention uses 2-arylimidazo[1,2-a]pyridine or substituted 2-arylimidazo[1,2-a]pyridine, α-chloroaryl ethyl ketone or substituted α-chloroaryl ethyl ketone as starting materials, and uses a rhodium catalyst to catalyze a carbon-hydrogen bond activation reaction to prepare imidazo[1,2-a]pyridine derivatives. The reaction conditions are mild, with high selectivity, high yield and safety, which is more conducive to industrial production.

[0041] This invention discloses for the first time a method for preparing different products of formylmethylimidazo[1,2-a]pyridine or substituted 2-arylimidazo[1,2-a]pyridine, α-chloroaryl ethyl ketone or substituted α-chloroaryl ethyl ketone as starting materials, by simultaneously adjusting the solvent and basic salt to regulate the reaction, thereby increasing the breadth of their applications.

[0042] Instruction manual illustrations

[0043] Figure 1 This is the reaction mechanism of the present invention.

[0044] Figure 2 It is the 1-phenyl-2-(2-phenylimidazo[1,2-a]pyridin-3-yl)ethyl-1-one in Example 1 1 H NMR spectrum.

[0045] Figure 3It is the 1-phenyl-2-(2-phenylimidazo[1,2-a]pyridin-3-yl)ethyl-1-one in Example 1 13 C NMR spectrum.

[0046] Figure 4 It is the 1-phenyl-2-(6-fluoro-2-phenylimidazo[1,2-a]pyridin-3-yl)ethyl-1-one in Example 2 1 H NMR spectrum.

[0047] Figure 5 It is the 1-phenyl-2-(6-fluoro-2-phenylimidazo[1,2-a]pyridin-3-yl)ethyl-1-one in Example 2 13 C NMR spectrum.

[0048] Figure 6 It is the 1-phenyl-2-(7-chloro-2-phenylimidazo[1,2-a]pyridin-3-yl)ethyl-1-one in Example 3 1 H NMR spectrum.

[0049] Figure 7 It is the 1-phenyl-2-(7-chloro-2-phenylimidazo[1,2-a]pyridin-3-yl)ethyl-1-one in Example 3 13 C NMR spectrum.

[0050] Figure 8 It is the 1-phenyl-2-(2-(4-bromophenyl)imidazo[1,2-a]pyridin-3-yl)ethyl-1-one in Example 4 1 H NMR spectrum.

[0051] Figure 9 It is the 1-phenyl-2-(2-(4-bromophenyl)imidazo[1,2-a]pyridin-3-yl)ethyl-1-one in Example 4 13 C NMR spectrum.

[0052] Figure 10 It is the methyl 4-(3-(2-oxo-2-phenylethyl)imidazo[1,2-a]pyridin-2-yl)benzoate in Example 5. 1 H NMR spectrum.

[0053] Figure 11 It is the methyl 4-(3-(2-oxo-2-phenylethyl)imidazo[1,2-a]pyridin-2-yl)benzoate in Example 5. 13 C NMR spectrum.

[0054] Figure 12 It is the 1-phenyl-2-(2-(3-fluorophenyl)imidazo[1,2-a]pyridin-3-yl)ethyl-1-one in Example 6 1H NMR spectrum.

[0055] Figure 13 It is the 1-phenyl-2-(2-(3-fluorophenyl)imidazo[1,2-a]pyridin-3-yl)ethyl-1-one in Example 6 13 C NMR spectrum.

[0056] Figure 14 It is the 1-(4-chlorophenyl)-2-(2-phenylimidazo[1,2-a]pyridin-3-yl)ethyl-1-one in Example 7 1 H NMR spectrum.

[0057] Figure 15 It is the 1-(4-chlorophenyl)-2-(2-phenylimidazo[1,2-a]pyridin-3-yl)ethyl-1-one in Example 7 13 C NMR spectrum.

[0058] Figure 16 It is the 2-(2-phenylimidazol[1,2-a]pyridin-3-yl)-1-(thiophen-3-yl)ethyl-1-one in Example 8 1 H NMR spectrum.

[0059] Figure 17 It is the 2-(2-phenylimidazol[1,2-a]pyridin-3-yl)-1-(thiophen-3-yl)ethyl-1-one in Example 8 13 C NMR spectrum.

[0060] Figure 18 It is the 1-(3,4-dichlorophenyl)-2-(2-phenylimidazo[1,2-a]pyridin-3-yl)ethyl-1-one in Example 9 1 H NMR spectrum.

[0061] Figure 19 It is the 1-(3,4-dichlorophenyl)-2-(2-phenylimidazo[1,2-a]pyridin-3-yl)ethyl-1-one in Example 9 13 C NMR spectrum.

[0062] Figure 20 It is the 6-phenylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine from Example 10. 1 H NMR spectrum.

[0063] Figure 21 It is the 6-phenylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine from Example 10. 13 C NMR spectrum.

[0064] Figure 22It is the 6-phenyl-9-methylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine from Example 11. 1 H NMR spectrum.

[0065] Figure 23 It is the 6-phenyl-9-methylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine from Example 11. 13 C NMR spectrum.

[0066] Figure 24 It is the 6-phenyl-10-chloronaphtho[1',2':4,5]imidazo[1,2-a]pyridine from Example 12. 1 H NMR spectrum.

[0067] Figure 25 It is the 6-phenyl-10-chloronaphtho[1',2':4,5]imidazo[1,2-a]pyridine from Example 12. 13 C NMR spectrum.

[0068] Figure 26 It is the 3-iodo-6-phenylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine from Example 13. 1 H NMR spectrum.

[0069] Figure 27 It is the 3-iodo-6-phenylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine from Example 13. 13 C NMR spectrum.

[0070] Figure 28 It is the 3-trifluoromethyl-6-phenylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine from Example 14. 1 H NMR spectrum.

[0071] Figure 29 It is the 3-trifluoromethyl-6-phenylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine from Example 14. 13 C NMR spectrum.

[0072] Figure 30 It is the methyl 6-phenylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine-3-carboxylate from Example 15. 1 H NMR spectrum.

[0073] Figure 31 It is the methyl 6-phenylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine-3-carboxylate from Example 15. 13 C NMR spectrum.

[0074] Figure 32 It is the 6-(4-chlorophenyl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine from Example 16. 1 H NMR spectrum.

[0075] Figure 33 It is the 6-(4-chlorophenyl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine from Example 16. 13 C NMR spectrum.

[0076] Figure 34 It is the 6-(3-methylphenyl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine from Example 17. 1 H NMR spectrum.

[0077] Figure 35 It is the 6-(3-methylphenyl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine from Example 17. 13 C NMR spectrum.

[0078] Figure 36 It is the 6-(3,4-dichlorophenyl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine from Example 18. 1 H NMR spectrum.

[0079] Figure 37 It is the 6-(3,4-dichlorophenyl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine from Example 18. 1 H NMR spectrum.

[0080] Figure 38 This is a schematic diagram of the fluorescence characteristics of Examples 10-18 under 365nm ultraviolet light. Detailed Implementation

[0081] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0082] This invention relates to the selective preparation of formylmethylimidazo[1,2-a]pyridine compounds or 6-arylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine compounds by using 2-arylimidazo[1,2-a]pyridine or substituted 2-arylimidazo[1,2-a]pyridine, α-chloroaryl ethyl ketone or substituted α-chloroaryl ethyl ketone as starting materials under heating conditions, and using a rhodium catalyst to catalyze a carbon-hydrogen bond activation reaction. By simultaneously adjusting the types of solvent and basic salt, the invention aims to prepare formylmethylimidazo[1,2-a]pyridine compounds or 6-arylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine compounds.

[0083] like Figure 1 As shown, the synthesis mechanism analysis of the present invention may be as follows:

[0084] In mechanism circle 1 (left figure), firstly, the active species generated by the reaction of the rhodium catalyst with acetate inserts into the C(3)-H of 2-arylimidazo[1,2-a]pyridine, forming intermediate A'. Subsequently, the oxygen atom of α-chloroaryl ketone coordinates with rhodium to generate alkyl species B', and the nucleophilic C(aryl)-Rh species further attacks the methylene group of α-chloroaryl ketone, generating α-aryl ketone intermediate C'. Finally, the formylmethylimidazo[1,2-a]pyridine compound is released from C' through a proton decomposition process, accompanied by the regeneration of the rhodium catalyst.

[0085] In mechanism circle 2 (right figure), firstly, under the synergistic effect of carbonate and alcohol solvent, the rhodium catalyst and 2-arylimidazo[1,2-a]pyridine are activated via CH bond to generate intermediate A. Subsequently, the oxygen atom of α-chloroaryl ketone coordinates with rhodium to generate alkyl species B, and the nucleophilic C(aryl)-Rh species further attacks the methylene group of α-chloroaryl ketone to generate α-aryl ketone intermediate C. Intermediate C undergoes inversion to give intermediate D. Finally, D undergoes intramolecular nucleophilic addition to give 6-arylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine compounds.

[0086] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0087] The 2-arylimidazo[1,2-a]pyridine used in the following examples was synthesized according to the literature Iron-Catalyzed Dehydrogenative sp3–sp2 Coupling via Direct Oxidative C–H Activation of Acetonitrile, Org. Lett. 2017, 19, 2226. The specific process is as follows:

[0088]

[0089] NaHCO3 (15.6 mmol, 1.56 equivalents) was added to an ethanol solution containing 2-bromoaryl ethyl ketone (10.0 mmol, 1.0 equivalent) and 2-aminopyridine (12.5 mmol, 1.25 equivalent). The reaction mixture was stirred at room temperature for 6 hours. After the reaction was completed, the precipitated solid was filtered, washed, dried, and recrystallized to obtain 2-arylimidazo[1,2-a]pyridine.

[0090] Example 1: Synthesis of 1-phenyl-2-(2-phenylimidazo[1,2-a]pyridin-3-yl)ethyl-1-one

[0091] In a 25 mL reactor, dichloro(pentamethylcyclopentadienyl)rhodium(III) dimer (0.0062 g, 0.01 mmol), 2-phenylimidazo[1,2-a]pyridine (0.039 g, 0.2 mmol), α-chloroacetophenone (0.046 g, 0.3 mmol), sodium acetate (0.0164 g, 0.2 mmol), and tetrahydrofuran (1 mL) were added as solvent. The mixture was stirred at 80 °C for 24 h. Column chromatography (silica gel, 200-300 mesh; developing solvent: petroleum ether: ethyl acetate) yielded 0.043 g of 1-phenyl-2-(2-phenylimidazo[1,2-a]pyridin-3-yl)ethyl-1-one, in 68% yield.

[0092] The CAS number of the dichloro(pentamethylcyclopentadienyl)rhodium(III) dimer in the raw materials of this embodiment is 12354-85-7, which was purchased from Titan Technology Exploration Platform;

[0093] α-Chloroacetophenone, CAS number 532-27-4, was purchased from Titan Technology Exploration Platform.

[0094] The reaction route in this embodiment is shown below:

[0095]

[0096] The product, 1-phenyl-2-(2-phenylimidazo[1,2-a]pyridin-3-yl)ethyl-1-one, is a brown solid. The product was characterized by nuclear magnetic resonance (NMR), see attached figure. Figure 2 and attached Figure 3 As shown, the specific spectral analysis is as follows: 1 H NMR(CDCl3,500MHz)δ7.96(d,J=5.0Hz,2H),7.88(d,J=10.0Hz,1H),7.67-7.63(m,3H),7.60-7.57 (m,1H),7.45-7.42(m,4H),7.39-7.37(m,1H),7.20-7.16(m,1H),6.79-6.76(m,1H),4.71(s,2H);13 C{ 1 H} NMR (CDCl3, 125MHz) δ194.8,145.2,144.7,135.6,134.4,133.9,128.9,128.7,128.6,128.5,127.9,124.5,123.8,117.5,113.7,112.4,34.7.

[0097] Example 2: Synthesis of 1-phenyl-2-(6-fluoro-2-phenylimidazo[1,2-a]pyridin-3-yl)ethyl-1-one

[0098] In a 25 mL reactor, dichloro(pentamethylcyclopentadienyl)rhodium(III) dimer (0.0062 g, 0.01 mmol), 2-phenyl-6-fluoro-imidazo[1,2-a]pyridine (0.043 g, 0.2 mmol), α-chloroacetophenone (0.046 g, 0.3 mmol), sodium acetate (0.0164 g, 0.2 mmol), and tetrahydrofuran (1 mL) were added as solvent. The mixture was stirred at 80 °C for 24 h. Column chromatography (silica gel, 200-300 mesh; developing solvent: petroleum ether: ethyl acetate) yielded 0.036 g of 1-phenyl-2-(6-fluoro-2-phenylimidazo[1,2-a]pyridin-3-yl)ethyl-1-one, in 54% yield.

[0099] The reaction route in this embodiment is shown below:

[0100]

[0101] The product, 1-phenyl-2-(6-fluoro-2-phenylimidazo[1,2-a]pyridin-3-yl)ethyl-1-one, is a yellow solid. The product was characterized by nuclear magnetic resonance (NMR), see attached figure. Figure 4 and attached Figure 5 As shown, the specific spectral analysis is as follows: 1 HNMR (CDCl3, 500MHz) δ7.99 (d, J = 5.0Hz, 2H), 7.90-7.89 (m, 1H), 7.67-7.62 (m, 4H), 7.49-7.40 (m, 5H), 7.17-7.14 (m, 1H), 4.70 (s, 2H); 13 C{ 1 H}NMR(CDCl3,125MHz)δ194.4,153.3(d, 1 J C-F =236.3Hz),146.1,142.9,135.5,134.1(d, 2 J C-F =20.0Hz),128.9,128.8,128.6(d,4 J C-F =3.8Hz), 128.1, 118.0 (d, 4 J C-F =8.8Hz), 116.4(d, 2 J C-F =25.0Hz),115.3,110.8,110.5,34.8.

[0102] Example 3: Synthesis of 1-phenyl-2-(7-chloro-2-phenylimidazo[1,2-a]pyridin-3-yl)ethyl-1-one

[0103] In a 25 mL reactor, dichloro(pentamethylcyclopentadienyl)rhodium(III) dimer (0.0062 g, 0.01 mmol), 2-phenyl-6-chloroimidazolo[1,2-a]pyridine (0.046 g, 0.2 mmol), α-chloroacetophenone (0.046 g, 0.3 mmol), sodium acetate (0.0164 g, 0.2 mmol), and tetrahydrofuran (1 mL) were added as solvent. The mixture was stirred at 80 °C for 24 h. Column chromatography (silica gel, 200-300 mesh; developing solvent: petroleum ether: ethyl acetate) yielded 0.034 g of 1-phenyl-2-(7-chloro-2-phenylimidazolo[1,2-a]pyridin-3-yl)ethyl-1-one, with a yield of 49%.

[0104] The reaction route in this embodiment is shown below:

[0105]

[0106] The product, 1-phenyl-2-(7-chloro-2-phenylimidazo[1,2-a]pyridin-3-yl)ethyl-1-one, is a yellow solid. The product was characterized by nuclear magnetic resonance (NMR), see attached figure. Figure 6 and attached Figure 7 As shown, the specific spectral analysis is as follows: 1 H NMR (CDCl3, 500MHz) δ7.98-7.96 (m, 2H), 7.77 (d, J = 10.0Hz, 1H), 7.67-7.61 ( m,4H),7.48-7.45(m,4H),7.42-7.40(m,1H),6.82-6.80(m,1H),4.72(s,2H); 13 C{ 1 H}NMR(CDCl3,125MHz)δ143.0,136.7,134.0,132.6,128.8,128.5,128.2,127.9,126.9,124.5,123.3,122.6,120.7,112.2.

[0107] Example 4: Synthesis of 1-phenyl-2-(2-(4-bromophenyl)imidazo[1,2-a]pyridin-3-yl)ethyl-1-one

[0108] In a 25 mL reactor, rhodium hexafluoroantimonylic acid (triacetonitrile-pentamethylcyclopentadienyl) (0.0083 g, 0.01 mmol), 2-(4-bromophenyl)imidazo[1,2-a]pyridine (0.055 g, 0.2 mmol), α-chloroacetophenone (0.046 g, 0.3 mmol), potassium acetate (0.0196 g, 0.2 mmol), and 1,4-dioxane (1 mL) were added as solvent. The mixture was stirred at 100 °C for 18 h. Separation was performed by column chromatography (silica gel, 200-300 mesh; developing solvent: n-hexane: ethyl acetate) to give 0.03 g of 1-phenyl-2-(2-(4-bromophenyl)imidazo[1,2-a]pyridin-3-yl)ethyl-1-one, yield 38%.

[0109] The reaction route in this embodiment is shown below:

[0110]

[0111] The product, 1-phenyl-2-(2-(4-bromophenyl)imidazo[1,2-a]pyridin-3-yl)ethyl-1-one, is a yellow solid. The product was characterized by nuclear magnetic resonance (NMR), see attached figure. Figure 8 and attached Figure 9 As shown, the specific spectral analysis is as follows: 1 HNMR(CDCl3,500MHz)δ8.01(d,J=10.0Hz,2H),7.92(d,J=10.0Hz,1H),7.70-7.6 3(m,2H),7.60-7.48(m,6H),7.27-7.23(m,1H),6.86-6.83(m,1H),4.73(s,2H); 13 C{ 1 H}NMR (CDCl3, 125MHz) δ194.6,145.3,143.6,135.6,134.0,133.4,131.9,130.1,129.0,128.5,124.7,123.8,122.2,117.7,113.9,112.6,34.7.

[0112] In this embodiment, the rhodium hexafluoroantimonylic acid (triacetonitrile-pentamethylcyclopentadienyl) used as a raw material has the CAS number 59738-27-1 and was purchased from Anaiji Chemical.

[0113] Example 5: Synthesis of methyl 4-(3-(2-oxo-2-phenylethyl)imidazo[1,2-a]pyridin-2-yl)benzoate

[0114] In a 25 mL reactor, rhodium hexafluoroantimonylic acid (triacetonitrile-pentamethylcyclopentadienyl) (0.0083 g, 0.01 mmol), 2-(4-carboxymethylphenyl)imidazo[1,2-a]pyridine (0.051 g, 0.2 mmol), α-chloroacetophenone (0.046 g, 0.3 mmol), potassium acetate (0.0196 g, 0.2 mmol), and 1,4-dioxane (1 mL) were added as solvent. The mixture was stirred at 100 °C for 18 h. Separation was performed by column chromatography (silica gel, 200-300 mesh; developing solvent: n-hexane: ethyl acetate) to give 0.03 g of methyl 4-(3-(2-oxo-2-phenylethyl)imidazo[1,2-a]pyridin-2-yl)benzoate, yield 40%.

[0115] The reaction route in this embodiment is shown below:

[0116]

[0117] The product, methyl 4-(3-(2-oxo-2-phenylethyl)imidazo[1,2-a]pyridin-2-yl)benzoate, is a yellow solid. The product was characterized by nuclear magnetic resonance (NMR), see attached figure. Figure 10 and attached Figure 11 As shown, the specific spectral analysis is as follows: 1 HNMR(CDCl3,500MHz)δ8.14-8.12(m,2H),8.02-8.00(m,2H),7.95-7.93(m,1H),7.78-7.76(m,2H),7.71-7.69 (m,1H),7.66-7.62(m,1H),7.51-7.48(m,2H),7.27-7.24(m,1H),6.87-6.84(m,1H),4.77(s,2H),3.95(s,3H); 13 C{ 1 H}NMR(CDCl3,125MHz)δ194.5,166.9,145.4,143.6,139.1,135.6,134.0,130. 0,129.4,129.0,128.5,128.4,124.9,123.8,117.8,114.6,112.7,52.1,34.7.

[0118] Example 6: Synthesis of 1-phenyl-2-(2-(3-fluorophenyl)imidazo[1,2-a]pyridin-3-yl)ethyl-1-one

[0119] In a 25 mL reactor, rhodium hexafluoroantimonylic acid (triacetonitrile-pentamethylcyclopentadienyl) (0.0083 g, 0.01 mmol), 2-(3-fluorophenyl)imidazo[1,2-a]pyridine (0.043 g, 0.2 mmol), α-chloroacetophenone (0.046 g, 0.3 mmol), potassium acetate (0.0196 g, 0.2 mmol), and 1,4-dioxane (1 mL) were added as solvent. The mixture was stirred at 100 °C for 18 h. Separation by column chromatography (silica gel, 200-300 mesh; developing solvent: n-hexane: ethyl acetate) yielded 0.029 g of 1-phenyl-2-(2-(3-fluorophenyl)imidazo[1,2-a]pyridin-3-yl)ethyl-1-one, with a yield of 44%.

[0120] The reaction route in this embodiment is shown below:

[0121]

[0122] The product, 1-phenyl-2-(2-(3-fluorophenyl)imidazo[1,2-a]pyridin-3-yl)ethyl-1-one, is a yellow solid. The product was characterized by nuclear magnetic resonance (NMR), see attached figure. Figure 12 and attached Figure 13 As shown, the specific spectral analysis is as follows: 1 HNMR(CDCl3,500MHz)δ8.02-8.00(m,2H),7.94-7.92(m,1H),7.71-7.69(m,1H),7.66-7.62(m,1H),7.51 -7.48(m,2H),7.45-7.41(m,3H),7.27-7.24(m,1H),7.11-7.08(m,1H),6.87-6.84(m,1H),4.76(s,2H); 13 C{ 1 H}NMR(CDCl3,125MHz)δ194.5,162.1,145.3,135.6,134.0,130.2(d, 4 J C-F =8.8Hz),128.9,128.5,124.8,124.2(d, 4 J C-F =3.8Hz),123.8,117.8,115.5(d, 2 J C-F =22.5Hz), 114.8(d, 2 J C-F =20.0Hz),114.0,112.6,34.6.

[0123] Example 7: Synthesis of 1-(4-chlorophenyl)-2-(2-phenylimidazo[1,2-a]pyridin-3-yl)ethyl-1-one

[0124] In a 25 mL reactor, pentamethylcyclopentadienyl rhodium acetate (0.0071 g, 0.02 mmol), 2-phenylimidazo[1,2-a]pyridine (0.039 g, 0.2 mmol), 4-chlorobenzoylmethyl chloride (0.057 g, 0.3 mmol), cesium acetate (0.0384 g, 0.2 mmol), and p-xylene (1 mL) were added as solvent. The mixture was stirred at 90 °C for 20 h. Column chromatography (silica gel, 200-300 mesh; developing solvent: petroleum ether: dichloromethane) yielded 0.026 g of 1-(4-chlorophenyl)-2-(2-phenylimidazo[1,2-a]pyridin-3-yl)ethyl-1-one, in 37% yield.

[0125] The reaction route in this embodiment is shown below:

[0126]

[0127] The product, 1-(4-chlorophenyl)-2-(2-phenylimidazo[1,2-a]pyridin-3-yl)ethyl-1-one, is a yellow solid. The product was characterized by nuclear magnetic resonance (NMR), see attached figure. Figure 14 and attached Figure 15 As shown, the specific spectral analysis is as follows: 1 HNMR(CDCl3,500MHz)δ7.97(d,J=5.0Hz,1H),7.87(d,J=5.0Hz,2H),7.70-7.66(m,3H),7 .51-7.47(m,2H),7.44-7.39(m,3H),7.26-7.23(m,1H),6.87-6.84(m,1H),4.72(s,2H); 13 C{ 1 H}NMR (CDCl3, 125MHz) δ193.6,145.3,144.8,140.4,134.4,133.9,130.0,129.2,128.8,128.6,128.1,124.6,123.8,117.7,113.2,112.5,34.8.

[0128] In this embodiment, the CAS number of the raw material, pentamethylcyclopentadienyl rhodium acetate, is 46930-83-0, and it was purchased from Anaiji Chemical.

[0129] 4-Chlorobenzoylmethyl chloride, CAS number 937-20-2, was purchased from Titan Technology Exploration Platform.

[0130] Example 8: Synthesis of 2-(2-phenylimidazolium[1,2-a]pyridin-3-yl)-1-(thien-3-yl)ethyl-1-one

[0131] In a 25 mL reactor, pentamethylcyclopentadienyl rhodium acetate (0.0071 g, 0.02 mmol), 2-phenylimidazo[1,2-a]pyridine (0.039 g, 0.2 mmol), 3-chloroacetylthiophene (0.048 g, 0.3 mmol), cesium acetate (0.0384 g, 0.2 mmol), and p-xylene (1 mL) were added as solvent. The mixture was stirred at 90 °C for 20 h. Column chromatography (silica gel, 200-300 mesh; developing solvent: petroleum ether: dichloromethane) yielded 0.044 g of 2-(2-phenylimidazo[1,2-a]pyridin-3-yl)-1-(thiophen-3-yl)ethyl-1-one, with a yield of 69%.

[0132] The reaction route in this embodiment is shown below:

[0133]

[0134] The product, 2-(2-phenylimidazolium[1,2-a]pyridin-3-yl)-1-(thiophen-3-yl)ethyl-1-one, is a yellow solid. The product was characterized by nuclear magnetic resonance (NMR), see attached image. Figure 16 and attached Figure 17 As shown, the specific spectral analysis is as follows: 1 H NMR(CDCl3,500MHz)δ8.02-7.99(m,2H),7.71-7.67(m,3H),7.54-7.53(m,1H),7.50-7.47(m, 2H),7.42-7.41(m,1H),7.33-7.31(m,1H),7.24-7.21(m,1H),6.85-6.83(m,1H),4.64(s,2H); 13 C{ 1 H} NMR (CDCl3, 125MHz) δ189.0,145.2,144.7,140.7,134.5,133.2,128.8,128.7,128.0,127.1,126.8,124.5,124.0,117.6,113.6,112.4,36.0.

[0135] In this embodiment, the CAS number of 2-chloro-1-(thiophen-3-yl)ethane-1-one was 50460-10-1, and it was purchased from Tianjin Anhao Biotechnology Co., Ltd.

[0136] Example 9: Synthesis of 1-(3,4-dichlorophenyl)-2-(2-phenylimidazo[1,2-a]pyridin-3-yl)ethyl-1-one

[0137] In a 25 mL reactor, pentamethylcyclopentadienyl rhodium acetate (0.0071 g, 0.02 mmol), 2-phenylimidazo[1,2-a]pyridine (0.039 g, 0.2 mmol), 2,3',4'-trichloroacetophenone (0.067 g, 0.3 mmol), cesium acetate (0.0384 g, 0.2 mmol), and p-xylene (1 mL) were added as solvent. The mixture was stirred at 90 °C for 20 h. Column chromatography (silica gel, 200-300 mesh; developing solvent: petroleum ether: dichloromethane) yielded 0.029 g of 1-(3,4-dichlorophenyl)-2-(2-phenylimidazo[1,2-a]pyridin-3-yl)ethyl-1-one, in 39% yield.

[0138] The reaction route in this embodiment is shown below:

[0139]

[0140] The product 1-(3,4-dichlorophenyl)-2-(2-phenylimidazo[1,2-a]pyridin-3-yl)ethyl-1-one is a yellow solid. The product was characterized by nuclear magnetic resonance (NMR), see attached figure. Figure 18 and attached Figure 19 As shown, the specific spectral analysis is as follows: 1 HNMR(CDCl3,500MHz)δ7.99-7.97(m,2H),7.72-7.66(m,4H),7.52-7.43(m,4H),7.27-7.23(m,1H),6.88-6.85(m,1H),4.70(s,2H); 13 C{ 1 H}NMR(CDCl3,125MHz)δ192.6,145.4,145.0,138.6,134.9,134.2,133.6,130. 9,130.6,128.9,128.6,128.2,127.5,124.7,123.8,117.7,112.7,112.6,34.9.

[0141] In this embodiment, the CAS number of 2-chloro-1-(thiophen-3-yl)ethane-1-one is 42981-08-8, and it was purchased from Titan Technology Exploration Platform.

[0142] Example 10: Synthesis of 6-phenylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine

[0143] In a 25 mL reactor, dichloro(pentamethylcyclopentadienyl)rhodium(III) dimer (0.0062 g, 0.01 mmol), 2-phenylimidazo[1,2-a]pyridine (0.039 g, 0.2 mmol), α-chloroacetophenone (0.046 g, 0.3 mmol), sodium carbonate (0.0212 g, 0.2 mmol), and trifluoroethanol (1 mL) were added as solvent. The mixture was stirred at 100 °C for 12 h. Column chromatography (silica gel, 200-300 mesh; developing solvent: petroleum ether: ethyl acetate) yielded 0.056 g of 6-phenylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine, 95% yield.

[0144] The reaction route in this embodiment is shown below:

[0145]

[0146] The product, 6-phenylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine, is a yellow solid. The product was characterized by nuclear magnetic resonance (NMR), see attached image. Figure 20 and attached Figure 21 As shown, the specific spectral analysis is as follows: 1 H NMR(CDCl3,500MHz)δ8.92(d,J=10.0Hz,1H),7.99(d,J=5.0Hz,1H),7.87-7.86(m,2H),7.7 5-7.71(m,1H),7.65-7.61(m,1H),7.58-7.52(m,6H),7.35-7.32(m,1H),6.61-6.58(m,1H); 13 C{ 1 H}NMR(CDCl3,125MHz)δ147.8,141.8,138.2,131.5,129.4,128.9,128.3,128.2, 128.2,127.3,126.6,126.41,126.37,126.1,123.6,123.0,122.3,118.0,110.6.

[0147] Example 11: Synthesis of 6-phenyl-9-methylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine

[0148] In a 25 mL reactor, dichloro(pentamethylcyclopentadienyl)rhodium(III) dimer (0.0062 g, 0.01 mmol), 2-phenyl-5-methylimidazo[1,2-a]pyridine (0.042 g, 0.2 mmol), α-chloroacetophenone (0.046 g, 0.3 mmol), sodium carbonate (0.0212 g, 0.2 mmol), and trifluoroethanol (1 mL) were added as solvent. The mixture was stirred at 100 °C for 12 h. Column chromatography (silica gel, 200-300 mesh; developing solvent: petroleum ether: ethyl acetate) yielded 0.048 g of 6-phenyl-9-methylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine, with a yield of 79%.

[0149] The reaction route in this embodiment is shown below:

[0150]

[0151] The product, 6-phenyl-9-methylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine, is a yellow solid. The product was characterized by nuclear magnetic resonance (NMR), see attached image. Figure 22 and attached Figure 23 As shown, the specific spectral analysis is as follows: 1 H NMR(CDCl3,500MHz)δ8.90(d,J=10.0Hz,1H),7.98(d,J=10.0Hz,1H),7.77(d,J=1 0.0Hz,1H),7.73-7.70(m,1H),7.64-7.55(m,8H),7.20-7.18(m,1H),2.14(s,3H); 13 C{ 1 H}NMR(CDCl3,125MHz)δ147.0,141.8,138.3,131.4,130.5,129.5,128.8,128.29,12 8.26,128.2,126.3,126.19,126.18,124.3,123.3,122.9,122.2,120.0,117.2,18.4.

[0152] Example 12: Synthesis of 6-phenyl-10-chloronaphtho[1',2':4,5]imidazo[1,2-a]pyridine

[0153] In a 25 mL reactor, dichloro(pentamethylcyclopentadienyl)rhodium(III) dimer (0.0062 g, 0.01 mmol), 2-phenyl-6-chloroimidazo[1,2-a]pyridine (0.046 g, 0.2 mmol), α-chloroacetophenone (0.046 g, 0.3 mmol), sodium carbonate (0.0212 g, 0.2 mmol), and trifluoroethanol (1 mL) were added as solvent. The mixture was stirred at 100 °C for 12 h. Column chromatography (silica gel, 200-300 mesh; developing solvent: petroleum ether: ethyl acetate) yielded 0.054 g of 6-phenyl-10-chloronaphtho[1',2':4,5]imidazo[1,2-a]pyridine, with a yield of 81%.

[0154] The reaction route in this embodiment is shown below:

[0155]

[0156] The product, 6-phenyl-10-chloronaphtho[1',2':4,5]imidazo[1,2-a]pyridine, is a yellow solid. The product was characterized by nuclear magnetic resonance (NMR), see attached image. Figure 24 and attached Figure 25 As shown, the specific spectral analysis is as follows: 1 H NMR (CDCl3, 500MHz) δ8.85 (d, J = 10.0 Hz, 1H), 7.99 (d, J = 10.0 Hz, 1H), 7.84 (s, 1H), 7.77-7.71 (m, 2H), 7.66-7.56 (m, 7H), 6.60-6.58 (m, 1H); 13 C{ 1 H}NMR(CDCl3,125MHz)δ147.5,142.2,137.8,133.9,131.6,129.4,129.1,12 8.5,128.3,127.8,126.7,126.6,125.9,124.1,123.0,122.2,116.6,112.4.

[0157] Example 13: Synthesis of 3-iodo-6-phenylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine

[0158] In a 25 mL reactor, rhodium hexafluoroantimonylic acid (triacetonitrile-pentamethylcyclopentadienyl) (0.0083 g, 0.01 mmol), 2-(4-iodophenyl)imidazo[1,2-a]pyridine (0.064 g, 0.2 mmol), α-chloroacetophenone (0.046 g, 0.3 mmol), potassium carbonate (0.0277 g, 0.2 mmol), and hexafluoroisopropanol (1 mL) were added as solvents, and the mixture was stirred at 80 °C for 24 h. Column chromatography (silica gel, 200-300 mesh; developing solvent: n-hexane: ethyl acetate) yielded 0.073 g of 3-iodo-6-phenylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine, with a yield of 87%.

[0159] The reaction route in this embodiment is shown below:

[0160]

[0161] The product, 3-iodo-6-phenylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine, is a yellow solid. The product was characterized by nuclear magnetic resonance (NMR), see attached image. Figure 26 and attached Figure 27 As shown, the specific spectral analysis is as follows: 1 H NMR(CDCl3,500MHz)δ8.59(d,J=5.0Hz,1H),8.32(d,J=5.0Hz,1H),7.94-7.92(m, 1H),7.82-7.80(m,2H),7.58-7.53(m,5H),7.38-7.32(m,2H),6.61-6.58(m,1H); 13 C{ 1 H}NMR(CDCl3,125MHz)δ148.0,141.6,137.7,136.7,134.8,133.0,129.3,129. 2,129.0,128.6,127.7,126.6,124.8,124.7,122.5,122.2,117.9,110.9,92.0.

[0162] Example 14: Synthesis of 3-trifluoromethyl-6-phenylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine

[0163] In a 25 mL reactor, rhodium hexafluoroantimonylic acid (triacetonitrile-pentamethylcyclopentadienyl) (0.0083 g, 0.01 mmol), 2-(4-trifluoromethylphenyl)imidazo[1,2-a]pyridine (0.053 g, 0.2 mmol), α-chloroacetophenone (0.046 g, 0.3 mmol), potassium carbonate (0.0277 g, 0.2 mmol), and hexafluoroisopropanol (1 mL) were added as solvent, and the mixture was stirred at 80 °C for 24 h. Column chromatography (silica gel, 200-300 mesh; developing solvent: n-hexane:ethyl acetate) yielded 0.066 g of 3-trifluoromethyl-6-phenylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine, 90% yield.

[0164] The reaction route in this embodiment is shown below:

[0165]

[0166] The product, 3-trifluoromethyl-6-phenylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine, is a yellow solid. The product was characterized by nuclear magnetic resonance (NMR), see attached image. Figure 28 and attached Figure 29 As shown, the specific spectral analysis is as follows: 1 H NMR (CDCl3, 500MHz) δ8.98 (d, J = 5.0Hz, 1H), 8.26 (s, 1H), 7.89-7.83 (m, 3H), 7.62-7.57 (m, 6H), 7.38-7.35 (m, 1H), 6.64-6.61 (m, 1H); 13 C{ 1 H}NMR(CDCl3,125MHz)δ148.2,141.3,137.6,130.3,129.7,129.3,129.1,128.7,128.2,128.0,127.6,126.6,125.7(d, 3 J C-F =12.5Hz), 124.0, 123.5(d, 2 J C-F =25.0Hz), 122.0(d, 3 J C-F =10.0Hz), 118.1, 111.1.

[0167] Example 15: Synthesis of methyl 6-phenylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine-3-carboxylate

[0168] In a 25 mL reactor, rhodium hexafluoroantimonylic acid (triacetonitrile-pentamethylcyclopentadienyl) (0.0083 g, 0.01 mmol), 2-(4-carboxymethylphenyl)imidazo[1,2-a]pyridine (0.051 g, 0.2 mmol), α-chloroacetophenone (0.046 g, 0.3 mmol), potassium carbonate (0.0277 g, 0.2 mmol), and hexafluoroisopropanol (1 mL) were added as solvents, and the mixture was stirred at 80 °C for 24 h. Separation by column chromatography (silica gel, 200-300 mesh; developing solvent: n-hexane:ethyl acetate) yielded 0.052 g of methyl 6-phenylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine-3-carboxylate, with a yield of 74%.

[0169] The reaction route in this embodiment is shown below:

[0170]

[0171] The product, methyl 6-phenylnaphtho[1',2':4,5]imidazo[1,2-a]pyridine-3-carboxylate, is a yellow solid. The product was characterized by nuclear magnetic resonance (NMR), see attached image. Figure 30 and attached Figure 31 As shown, the specific spectral analysis is as follows: 1 HNMR(CDCl3,500MHz)δ8.90(d,J=10.0Hz,1H),8.72(s,1H),8.30-8.28(m,1H),7.85 -7.83(m,2H),7.63-7.56(m,6H),7.37-7.34(m,1H),6.62-6.60(m,1H),4.00(s,3H); 13 C{ 1 H}NMR(CDCl3,125MHz)δ167.3,148.2,141.3,137.7,131.0,130.6,129.3,129.1,129. 0,128.6,128.5,127.8,127.7,126.6,126.0,124.3,123.6,123.2,118.1,111.0,52.2.

[0172] Example 16: Synthesis of 6-(4-chlorophenyl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine

[0173] In a 25 mL reactor, 0.0071 g (0.02 mmol) of pentamethylcyclopentadienyl rhodium acetate, 0.039 g (0.2 mmol) of 2-phenylimidazo[1,2-a]pyridine, 0.057 g (0.3 mmol) of 4-chlorobenzoylmethyl chloride, 0.0148 g (0.2 mmol) of lithium carbonate, and 1 mL of methanol were added as solvent. The mixture was stirred at 90 °C for 18 h. Column chromatography (silica gel, 200-300 mesh; developing solvent: petroleum ether: dichloromethane) yielded 0.061 g of 6-(4-chlorophenyl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine, with a yield of 93%.

[0174] The reaction route in this embodiment is shown below:

[0175]

[0176] The product, 6-(4-chlorophenyl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine, is a yellow solid. The product was characterized by nuclear magnetic resonance (NMR), see attached image. Figure 32 and attached Figure 33 As shown, the specific spectral analysis is as follows: 1 H NMR(CDCl3,500MHz)δ8.90(d,J=10.0Hz,1H),7.97(d,J=10.0Hz,1H),7.89-7.85(m,2H),7.74-7.71(m ,1H),7.65-7.61(m,1H),7.58-7.55(m,2H),7.53-7.50(m,3H),7.38-7.34(m,1H),6.67-6.64(m,1H); 13 C{ 1 H}NMR(CDCl3,125MHz)δ147.9,141.9,136.7,134.5,131.4,130.8,129.2,128.2 ,127.4,126.8,126.6,126.5,126.3,126.2,123.8,123.0,122.0,118.1,110.9.

[0177] Example 17: Synthesis of 6-(3-methylphenyl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine

[0178] In a 25 mL reactor, 0.0071 g (0.02 mmol) of pentamethylcyclopentadienyl rhodium acetate, 0.043 g (0.2 mmol) of 2-phenylimidazo[1,2-a]pyridine, 0.051 g (0.3 mmol) of 3-methyl-2-chloroacetylbenzene, 0.0148 g (0.2 mmol) of lithium carbonate, and 1 mL of methanol were added as solvent. The mixture was stirred at 90 °C for 18 h. Column chromatography (silica gel, 200-300 mesh; developing solvent: petroleum ether: dichloromethane) yielded 0.058 g of 6-(3-methylphenyl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine, with a yield of 94%.

[0179] The reaction route in this embodiment is shown below:

[0180]

[0181] The product, 6-(3-methylphenyl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine, is a yellow solid. The product was characterized by nuclear magnetic resonance (NMR), see attached image. Figure 34 and attached Figure 35 As shown, the specific spectral analysis is as follows: 1 H NMR(CDCl3,500MHz)δ8.92(d,J=5.0Hz,1H),7.99(d,J=10.0Hz,1H),7.92-7.86(m,2H),7.75-7.71(m,1H ),7.65-7.63(m,1H),7.57(s,1H),7.48-7.45(m,1H),7.41-7.33(m,4H),6.63-6.60(m,1H),2.49(s,3H); 13 C{ 1 H}NMR(CDCl3,125MHz)δ147.8,141.7,138.7,138.1,131.5,130.1,129.1,128.8,128. 4,128.2,127.3,126.7,126.4,126.3,126.1,123.5,123.0,122.4,117.9,110.6,21.6.

[0182] In this embodiment, the CAS number of 3-methyl-2-chloroacetylbenzene is 21886-54-4, and it was purchased from Shanghai Bide Pharmaceutical Technology Co., Ltd.

[0183] Example 18: Synthesis of 6-(3,4-dichlorophenyl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine

[0184] In a 25 mL reactor, pentamethylcyclopentadienyl rhodium acetate (0.0071 g, 0.02 mmol), 2-phenylimidazo[1,2-a]pyridine (0.039 g, 0.2 mmol), 2,3',4'-trichloroacetophenone (0.067 g, 0.3 mmol), lithium carbonate (0.0148 g, 0.2 mmol), and methanol (1 mL) were added as solvent. The mixture was stirred at 90 °C for 18 h. Column chromatography (silica gel, 200-300 mesh; developing solvent: petroleum ether: dichloromethane) yielded 0.063 g of 6-(3,4-dichlorophenyl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine, with a yield of 87%.

[0185] The reaction route in this embodiment is shown below:

[0186]

[0187] The product, 6-(3,4-dichlorophenyl)naphtho[1',2':4,5]imidazo[1,2-a]pyridine, is a yellow solid. The product was characterized by nuclear magnetic resonance (NMR), see attached image. Figure 36 and attached Figure 37 As shown, the specific spectral analysis is as follows: 1 H NMR(CDCl3,500MHz)δ8.89(d,J=10.0Hz,1H),7.97(d,J=5.0Hz,1H),7.92-7.87(m,2H),7 .76-7.72(m,2H),7.67-7.63(m,2H),7.52(s,1H),7.44-7.37(m,2H),6.73-6.70(m,1H); 13 C{ 1 H}NMR(CDCl3,125MHz)δ147.9,141.9,138.3,133.2,132.8,131.3,131.2,130.9,128.8 ,128.3,127.5,126.9,126.6,126.3,126.2,125.5,123.9,123.1,121.6,118.2,111.2.

[0188] The fluorescence properties of the products prepared in Examples 10 to 18 under 365 nm ultraviolet light were tested, and the results are shown in the appendix. Figure 38 As shown, by Figure 38 It is evident that the products prepared in Examples 10 to 18 have potential applications as organic optoelectronic materials.

[0189] The present invention and its embodiments have been described above. This description is not restrictive, and the embodiments shown are only one of the embodiments of the present invention. The actual structure is not limited to this. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A method for the selective preparation of imidazo[1,2-a]pyridine derivatives catalyzed by rhodium, synergistically regulated by a solvent and a basic salt, characterized in that, Under the condition of heating, formylmethyl imidazo[1,2-a]pyridine compounds or 6-aryl naphtho[1',2':4,5]imidazo[1,2-a]pyridine compounds are selectively prepared by using compound A and compound B as starting materials, using metal rhodium catalyst to catalyze carbon-hydrogen bond activation reaction, and by simultaneously adjusting the types of solvent and basic salt; The compound A is 2-aryl imidazo[1,2-a]pyridine or substituted 2-aryl imidazo[1,2-a]pyridine; The compound B is α-chloro aryl ethanone or substituted α-chloro aryl ethanone; The solvent for selectively preparing the formylmethyl imidazo[1,2-a]pyridine compound is selected from at least one of tetrahydrofuran, 1,4-dioxane or p-xylene, and the basic salt is selected from acetate; The solvent for selectively preparing the 6-aryl naphtho[1',2':4,5]imidazo[1,2-a]pyridine compound is selected from at least one of trifluoroethanol, hexafluoroisopropanol or methanol, and the basic salt is selected from carbonate; The structural formula of the formylmethyl imidazo[1,2-a]pyridine compound is shown in the following formula (I): The structural formula of the 6-aryl naphtho[1',2':4,5]imidazo[1,2-a]pyridine compound is shown in the following formula (II) In the formula (I) and formula (II), R1, R2 and R3 are independently selected from one of hydrogen, alkyl, halogen, ester group or trifluoromethyl.

2. The method for synergistically regulating rhodium-catalyzed selective preparation of imidazo[1,2-a]pyridine derivatives by solvent and basic salt according to claim 1, characterized in that, The metal rhodium catalyst is selected from at least one of dichloro(pentamethylcyclopentadienyl) rhodium (III) dimer, hexafluoroantimonate(triethyl nitrile-base-pentamethylcyclopentadienyl) rhodium and pentamethylcyclopentadienyl rhodium acetate.

3. The method for the selective preparation of imidazo[1,2-a]pyridine derivatives catalyzed by rhodium with the synergistic control of solvents and basic salts according to claim 1, characterized in that, The acetate is selected from at least one of sodium acetate and cesium acetate.

4. The method for synergistically modulating rhodium catalysis by a solvent and a basic salt for selectively preparing imidazo[1,2-a]pyridine derivatives according to claim 1, characterized in that, The carbonate is selected from at least one of sodium carbonate and lithium carbonate.

5. The method for synergistically regulating rhodium catalysis to selectively prepare imidazo[1,2-a]pyridine derivatives by using solvent and basic salt according to claim 1, wherein The substituted 2-aryl imidazo[1,2-a]pyridine is at least one of para or meta position of the benzene ring of 2-aryl imidazo[1,2-a]pyridine substituted by a substituent; The substituted α-chloro aryl ethanone is at least one of para or meta position of the benzene ring of α-chloro aryl ethanone substituted by a substituent; The substituent is selected from one of alkyl, halogen, ester group or trifluoromethyl.

6. The method for synergistically regulating rhodium catalysis to selectively prepare imidazo[1,2-a]pyridine derivatives by using solvent and basic salt according to claim 5, wherein The 2-aryl imidazo[1,2-a]pyridine or substituted α-chloro aryl ethanone is shown in the following formula (III): The α-chloro aryl ethanone or substituted α-chloro aryl ethanone is shown in the following formula (IV): In the formula (III) and formula (IV), R1, R2 and R3 are independently selected from one of hydrogen, alkyl, halogen, ester group and trifluoromethyl.

7. The method for the selective preparation of imidazo[1,2-a]pyridine derivatives catalyzed by rhodium with the synergistic regulation of solvents and basic salts according to claim 1, characterized in that, The formylmethyl imidazo[1,2-a]pyridine compound with the structural formula as formula (I) is specifically any one of the following compounds:

8. The method for synergistically modulating rhodium catalyzed selective preparation of imidazo[1,2-a]pyridine derivatives by solvent and basic salt according to claim 1, characterized in that, The 6-aryl naphtho[1',2':4,5]imidazo[1,2-a]pyridine compounds of structural formula (II) are specifically any one of the following compounds:

9. The method for the selective preparation of imidazo[1,2-a]pyridine derivatives catalyzed by rhodium according to any one of claims 1 to 8, characterized in that, It specifically comprises the following steps: 1) Compound A, compound B, catalyst and basic salt are added into a solvent for dispersion; The molar ratio of compound A, compound B and rhodium catalyst is 1:(0.01-1):0.1; The molar ratio of compound A and basic salt is 1:(1-3); 2) Stirring the reaction at a temperature of 80-100℃, and after separation of the reaction material, it is ready.

10. The use of the formylmethyl imidazo[1,2-a]pyridine compound or 6-aryl naphtho[1',2':4,5]imidazo[1,2-a]pyridine compound prepared by the method of synergistically regulating rhodium catalysis to selectively prepare imidazo[1,2-a]pyridine derivatives with a solvent and a basic salt according to any one of claims 1 to 9 in the preparation of a drug or an organic optoelectronic material.

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