A method for copper-catalyzed synthesis of alpha, beta-unsaturated aldehyde compounds

Abstract

The application provides a method for synthesizing an alpha, beta-unsaturated aldehyde compound by using copper as a catalyst, using an alkyne as a reaction raw material, using silane as a hydrogen source, using N, N-dimethylformamide dimethyl acetal as a formyl source, and using a carbene copper as a catalyst to efficiently synthesize the alpha, beta-unsaturated aldehyde compound. The method avoids the use of flammable and explosive and toxic synthesis gas, the raw material is cheap and easy to obtain, the reaction condition is mild, the operation is simple, the substrate has a wide application range, and excellent stereoselectivity and regioselectivity are obtained. The product alpha, beta-unsaturated aldehyde compound is an important intermediate for synthesizing complex molecules such as drugs and natural products, and the method has important significance in the fields of medicines, pesticides and fine chemicals.

Description

TECHNICAL FIELD

[0001] The application relates to a copper-catalyzed synthesis method of an alpha, beta-unsaturated aldehyde compound and belongs to the field of organic synthesis and fine chemical industry. BACKGROUND

[0002] The hydroformylation reaction of carbon-carbon unsaturated bond is one of the most powerful tools for synthesizing aldehyde compounds, which has important significance in academic research and industrial production. Alpha, beta-unsaturated aldehyde compounds are important intermediates in organic synthesis, and the hydroformylation reaction of alkynes is the preferred method for synthesizing alpha, beta-unsaturated aldehydes. Compared with the more studied hydroformylation reaction of alkenes, the corresponding alkyne reaction has received less attention, and the main challenge is how to inhibit the hydrogenation reaction to generate saturated aldehydes and alkenes. In the past few decades, rhodium and palladium have been found to be efficient and highly selective catalysts, which provide a class of hydroformylation methods for alkynes. However, these catalytic systems have a common shortcoming, that is, using highly flammable and toxic synthetic gas (CO / H2) as a hydrogen source and formyl source.

[0003] In 2019, the You Jingsong research group reported the first rhodium-catalyzed alkyne hydroformylation without synthetic gas. The method provides hydrogen source and formyl source through n-butyl aldehyde. This new method effectively overcomes the challenge brought by synthetic gas (Angew. Chem., Int. Ed., 2019, 58, 7440-7444). Subsequently, the Ding Kui-ling and Zhou Qilin team reported another rhodium-catalyzed alkyne hydroformylation without synthetic gas, using formic acid as a substitute for synthetic gas (Org. Lett., 2021, 23, 2074-2077). Recently, the Chikkali research group uses formamide as a synthetic gas substitute and uses iron to catalyze the hydroformylation of alkynes (ChemCatChem, 2023, 15, e202201394). In view of the important position of alpha, beta-unsaturated aldehyde in synthetic chemistry, it is of great significance to continue to find high-selectivity catalytic systems and cheap and easily available synthetic gas substitutes for chemical products in the fields of medicine, pesticides and fine chemicals.

[0004] In recent years, copper-catalyzed hydrocarbonylation of multi-carbon-carbon unsaturated bonds has become a research hotspot. The catalytic cycle generally starts from the formation of Cu-H from copper, silane and an external base, followed by migration insertion into a double bond or a triple bond to generate an organocopper intermediate, and further carbon capture by an electrophilic reagent to generate a functionalized organic compound (Chem. Rev., 2008, 108, 2916-2927; Chem. Rev., 2016, 116, 8318-8372). N,N-dimethylformamide dimethyl acetal can generate highly active iminium cation and methoxy anion in situ (Tetrahedron Lett., 2004, 45, 5043-5046; RSC Adv., 2015, 5, 91326-91329; J. Org. Chem., 2014, 79, 936-942). The methoxy anion can activate silane and copper to generate a copper hydride reagent. The alkyne undergoes migration insertion with the copper hydride to generate an alkenyl copper reagent. The iminium cation acts as an electrophilic trapping reagent to capture the intermediate alkenyl copper reagent.

[0005] The present application uses alkyne as a reaction raw material, silane as a hydrogen source, N,N-dimethylformamide dimethyl acetal as a formyl source, and carbene copper as a catalyst to efficiently synthesize α,β-unsaturated aldehyde compounds. The method uses commercially available copper as a catalyst and inexpensive and readily available N,N-dimethylformamide dimethyl acetal as a formyl source, avoiding the use of toxic and flammable and explosive synthetic gas. The method is simple to operate, the reaction conditions are mild, the substrate applicability is wide, and excellent stereo- and regioselectivity is achieved. SUMMARY

[0006] The present application aims to provide a method for copper-catalyzed synthesis of α,β-unsaturated aldehyde compounds: using alkyne as a reaction raw material, N,N-dimethylformamide dimethyl acetal as a formyl source, silane as a hydrogen source, and carbene copper as a catalyst to synthesize α,β-unsaturated aldehyde compounds.

[0007] To achieve the above-mentioned application purposes, the present application provides a method for copper-catalyzed synthesis of α,β-unsaturated aldehyde compounds, and the synthesis path is as follows:

[0008]

[0009] The present application provides a method for copper-catalyzed synthesis of α,β-unsaturated aldehyde compounds, and the steps are as follows:

[0010] A dry Schlenk reaction tube is charged with a copper carbene catalyst and an alkyne of Formula 1, vacuumed using a Schlenk double-tube, and argon is introduced thereinto three times. Then, a solvent, a silane, and an N,N-dimethylformamide dimethyl acetal of Formula 2 are introduced thereinto under argon, the reaction system is sealed, the temperature of the reaction system is controlled at 80-110°C, and the reaction is stirred for 24-36 hours. After that, saturated NH4Cl solution and ethyl acetate are introduced thereinto to quench, the mixture is stirred for 30 minutes, and the separated organic phase is concentrated. The concentrated solution is separated by silica gel column chromatography to obtain an α,β-unsaturated aldehyde compound of Formula 3.

[0011] wherein Ar in Formula 1 and Formula 3 is selected from aryl, and R is selected from aryl or alkyl; the silane is selected from one of (C2H5O)3SiH, (C2H5O)2CH3SiH, or (C6H5)3SiH; the copper carbene catalyst is selected from one of IMesCuCl, IPrCuCl, SIMesCuCl, or SIPrCuCl; and the solvent is selected from one of 1,4-dioxane, toluene, or n-hexane.

[0012] In the above method, the molar ratio of the amounts of the alkyne 1, the N,N-dimethylformamide dimethyl acetal 2, the silane, and the copper carbene catalyst is 1.0:5.0-8.0:5.0-8.0:0.1-0.2. DETAILED DESCRIPTION

[0013] The present application will be further understood by the following examples, which are not intended to limit the scope of the present application.

[0014] Example 1: Preparation of (E)-2,3-diphenylpropenal

[0015]

[0016] A dry Schlenk reaction tube is charged with 19.5 mg (0.04 mmol) of a copper carbene catalyst IPrCuCl and 36 mg (0.2 mmol) of 1,2-diphenylacetylene, vacuumed using a Schlenk double-tube, and argon is introduced thereinto three times. Then, 0.5 mL of toluene, 256 uL (1.6 mmol) of methyldiethoxysilane, and 210 uL (1.6 mmol) of N,N-dimethylformamide dimethyl acetal are introduced thereinto under argon, the reaction system is sealed, the temperature of the reaction system is controlled at 110°C, and the reaction is stirred for 36 hours. After that, saturated NH4Cl solution and ethyl acetate are introduced thereinto to quench, the mixture is stirred for 30 minutes, and the separated organic phase is concentrated. The concentrated solution is separated by silica gel column chromatography to obtain (E)-2,3-diphenylpropenal at a yield of 46%. 1H NMR (500 MHz, CDC13) δ 9.77 (s, 1H), 7.40 (m, 4H), 7.32-7.26 (m, 1H), 7.25-7.17 (m, 6H). 13 C NMR (126 MHz, CDC13) δ 194.02, 150.26, 141.93, 134.15, 133.46, 130.87, 130.35, 129.46, 128.99, 128.63, 128.44.

[0017] Example 2: Preparation of (E)-2,3-di(4-methylphenyl)acrylaldehyde

[0018]

[0019] Into a dry Schlenk reaction tube, 8.0 mg (0.02 mmol) of carbene copper IMesCuCl and 41.2 mg (0.2 mmol) of 1,2-di(4-methylphenyl)acetylene were added, vacuumized using a Schlenk double-tube, and argon was introduced. This process was repeated three times. Under the argon atmosphere, 0.5 mL of 1,4-dioxane, 192 uL (1.2 mmol) of methyldiethoxysilane, and 158 uL (1.2 mmol) of N,N-dimethylformamide dimethyl acetal were added, and the reaction system was sealed. The temperature of the reaction system was controlled at 100°C, and the reaction was stirred for 30 hours. Saturated NH4Cl solution and ethyl acetate were added to quench the reaction, and the mixture was stirred for 30 minutes. The separated organic phase was concentrated, and the concentrated solution was separated by silica gel column chromatography to obtain (E)-2,3-di-p-tolylacrylaldehyde with a yield of 65%. 1 H NMR (500 MHz, CDC13) δ 9.72 (s, 1H), 7.32 (s, 1H), 7.21 (d, J = 7.8 Hz, 2H), 7.14-7.02 (m, 6H), 2.38 (s, 3H), 2.30 (s, 3H). 13 C NMR (126 MHz, CDC13) δ 194.26, 150.25, 141.11, 140.84, 138.09, 131.53, 130.89, 130.60, 129.70, 129.31, 129.27, 21.56, 21.49.

[0020] Example 3: Preparation of (E)-2,3-di(4-fluorophenyl)acrylaldehyde

[0021]

[0022] 16.2 mg (0.04 mmol) of carbene copper IMesCuCl and 42.8 mg (0.2 mmol) of 1,2-bis(4-fluorophenyl)acetylene were added to a dry Schlenk reaction tube. The tube was evacuated using a Schlenk double-row tube and purged with argon gas three times. Under argon gas purging, 0.5 mL of 1,4-dioxane, 184 μL (1.0 mmol) of triethoxysilane and 132 μL (1.0 mmol) of N,N-dimethylformamide dimethyl acetal were added. The reaction system was sealed and the temperature was controlled at 100 °C. After stirring for 24 hours, saturated NH4Cl solution and ethyl acetate were added to quench the reaction. The mixture was stirred for 30 minutes, extracted, and separated. The separated organic phase was concentrated, and the concentrate was separated by silica gel column chromatography to obtain (E)-2,3-bis(4-fluorophenyl)propenal with a yield of 79%. 1 H NMR (500MHz, CDCl3) δ9.74 (s, 1H), 7.36 (s, 1H), 7.24-7.06 (m, 6H), 6.94 (t, J = 8.6Hz, 2H). 13 CNMR (126MHz, CDCl3) δ193.61, 163.69 (d, J = 253.3Hz), 162.86 (d, J = 248.2Hz), 149.24, 140.58 (d, J = 1.6Hz), 132.82 (d, J=8.5Hz), 131.36 (d, J=8.1Hz), 130.19 (d, J=3.4Hz), 128.93 (d, J=3.4Hz), 116.23 (d, J=21.5Hz), 115.96 (d, J=21.8Hz).

[0023] Example 4: Preparation of (E)-2,3-bis(4-chlorophenyl)propenal

[0024]

[0025] 16.2 mg (0.04 mmol) of carbene copper SIMES CuCl and 50 mg (0.2 mmol) of 1,2-di(4-chlorophenyl)acetylene were added to a dry Schlenk reaction tube. The tube was evacuated using a Schlenk double-row tube and purged with argon gas three times. Under argon gas purging, 0.5 mL of 1,4-dioxane, 184 μL (1.0 mmol) of triethoxysilane and 132 μL (1.0 mmol) of N,N-dimethylformamide dimethyl acetal were added. The reaction system was sealed and the temperature was controlled at 100 °C. After stirring for 30 hours, saturated NH4Cl solution and ethyl acetate were added to quench the reaction. The mixture was stirred for 30 minutes, extracted, and separated. The separated organic phase was concentrated, and the concentrate was separated by silica gel column chromatography to obtain (E)-2,3-di(4-chlorophenyl)propenal with a yield of 45%.1 H NMR (500 MHz, CDC13) δ 9.74 (s, 1H), 7.39-7.37 (m, 2H), 7.35 (s, 1H), 7.24-7.22 (m, 2H), 7.13-7.12 (m, 4H). 13 CNMR (126 MHz, CDC13) δ 193.29, 149.05, 141.05, 136.62, 134.78, 132.30, 131.91, 131.37, 130.93, 129.42, 129.13.

[0026] Example 5: Preparation of (E)-4,4'-(3-oxoprop-1,2- dienyl)-dibenzoic acid di-tert-butyl ester

[0027]

[0028] Into a dry Schlenk reaction tube, 16.2 mg (0.04 mmol) of carbene copper IMesCuCl and 75.6 mg (0.2 mmol) of 4,4'-(ethyn-l,2-diyl)dibenzoic acid di-tert-butyl ester were added, vacuumed using a Schlenk double-tube, argon was introduced, and this process was repeated three times. Under the condition of argon introduction, 0.5 mL of 1,4-dioxane, 184 uL (1.0 mmol) of triethoxysilane, and 132 uL (1.0 mmol) of N,N-dimethylformamide dimethyl acetal were added, the reaction system was sealed, the temperature of the reaction system was controlled at 100°C, and the reaction was stirred for 24 hours. After quenching with saturated NH4Cl solution and ethyl acetate, stirring was performed for 30 minutes, the separated organic phase was concentrated, and the concentrated solution was separated by silica gel column chromatography to obtain (E)-4,4'-(3-oxoprop-1,2-dienyl)-dibenzoic acid di-tert-butyl ester with a yield of 53%; 1 H NMR (500 MHz, CDC13) δ 9.80 (s, 1H), 8.03 (d, J = 8.3 Hz, 2H), 7.85 (d, J = 8.4 Hz, 2H), 7.47 (s, 1H), 7.23 (dd, J = 8.2, 5.4 Hz, 4H), 1.61 (s, 9H), 1.57 (s, 9H). 13 C NMR (126 MHz, CDC13) δ 193.06, 165.46, 164.93, 149.13, 142.46, 137.52, 137.28, 133.34, 132.21, 130.41, 130.05, 129.67, 129.48, 81.64, 81.38, 28.31, 28.24.

[0029] Example 6: Preparation of (E)-2,3-di(3-methylphenyl)prop-2- enal

[0030]

[0031] Into a dry Schlenk tube was added 16.2 mg (0.04 mmol) of carbene copper IMesCuCl and 41.2 mg (0.2 mmol) of 1,2-di(3-methylphenyl)acetylene, vacuumed using a Schlenk double-tube, purged with argon, and 0.5 mL of 1,4-dioxane, 184 uL (1.0 mmol) of triethoxysilane, and 132 uL (1.0 mmol) of N,N-dimethylformamide dimethyl acetal were added under argon, the reaction system was sealed, and the temperature was controlled at 100 °C. After stirring for 36 h, the reaction was quenched with saturated NH4Cl solution and ethyl acetate, stirred for 30 min, and extracted and separated. The separated organic phase was concentrated, and the concentrate was separated by silica gel column chromatography to obtain (E)-2,3-di(3-methylphenyl)acrylaldehyde in a yield of 30%. 1 H NMR (500 MHz, CDC13) δ 9.74 (s, 1H), 7.33 (s, 1H), 7.29 (t, J = 7.6 Hz, 1H), 7.19 (d, J = 7.6 Hz, 1H), 7.11-6.95 (m, 6H), 2.35 (s, 3H), 2.23 (s, 3H). 13 C NMR (126 MHz, CDC13) δ 194.22, 150.39, 141.98, 138.56, 138.21, 134.12, 133.52, 131.90, 131.15, 129.87, 129.16, 128.84, 128.44, 127.86, 126.39, 21.57, 21.37.

[0032] Example 7: Preparation of (E)-2,3-di(3-trifluoromethylphenyl)acrylaldehyde

[0033]

[0034] Into a dry Schlenk tube, 16.2 mg (0.04 mmol) of copper carbene IMesCuCl and 62.8 mg (0.2 mmol) of 1,2-di(3-trifluoromethylphenyl)acetylene, 260 mg (1.0 mmol) of triphenylsilane were added, vacuumed using a Schlenk double-tube, and argon was introduced. This process was repeated three times. Under the argon atmosphere, 0.5 mL of 1,4-dioxane and 132 uL (1.0 mmol) of N,N-dimethylformamide dimethyl acetal were added, the reaction system was sealed, and the temperature of the reaction system was controlled at 100 °C. After stirring for 36 h, saturated NH4Cl solution and ethyl acetate were added for quenching, and stirring was performed for 30 min. The separated organic phase was concentrated, and the concentrated solution was separated by silica gel column chromatography to obtain (E)-2,3-di(3-trifluoromethylphenyl)prop-2-enal with a yield of 65%. 1 HNMR (500 MHz, CDC13) δ 9.81 (s, 1H), 7.67 (d, J = 7.9 Hz, 1H), 7.56 (t, J = 7.7 Hz, 2H), 7.49 (s, 1H), 7.45 (s, 1H), 7.43-7.30 (m, 4H). 13 C NMR (126 MHz, CDC13) δ 192.76, 148.83, 141.85, 134.29, 133.45, 133.02, 131.51, 129.68, 129.38, 127.33, 127.05, 126.43 (d, J = 3.8 Hz), 125.63 (d, J = 3.7 Hz), 125.01, 124.66, 122.84, 122.49.

[0035] Example 8: Preparation of (E)-2,3-di(3-cyanophenyl)prop-2-enal

[0036]

[0037] Into a dry Schlenk tube, 19.6 mg (0.04 mmol) of copper carbene SIPrCuCl and 45.6 mg (0.2 mmol) of 1,2-di(3-cyanophenyl)acetylene were added, vacuumed using a Schlenk double-tube, and argon was introduced. This process was repeated three times. Under the argon atmosphere, 0.5 mL of n-hexane, 295 uL (1.6 mmol) of triethoxysilane, and 210 uL (1.6 mmol) of N,N-dimethylformamide dimethyl acetal were added, the reaction system was sealed, and the temperature of the reaction system was controlled at 80 °C. After stirring for 36 h, saturated NH4Cl solution and ethyl acetate were added for quenching, and stirring was performed for 30 min. The separated organic phase was concentrated, and the concentrated solution was separated by silica gel column chromatography to obtain (E)-2,3-di(3-cyanophenyl)prop-2-enal with a yield of 44%. 1H NMR (500 MHz, CDC13) δ 9.80 (s, 1H), 7.75-7.70 (m, 1H), 7.62 (t, J = 8.2 Hz, 1H), 7.56 (t, J = 7.7 Hz, 1H), 7.48 (s, 3H), 7.44-7.33 (m, 3H). 13 C NMR (126 MHz, CDC13) δ 192.21, 148.04, 141.43, 134.58, 134.03, 134.00, 133.75, 133.66, 133.03, 132.56, 130.04, 129.81, 129.54, 118.19, 117.77, 113.47, 113.45.

[0038] Example 9: Preparation of (E)-2,3-di(2-chlorophenyl)prop-2-enal

[0039]

[0040] Into a dry Schlenk reaction tube, 16.2 mg (0.04 mmol) of carbene copper IMesCuCl and 50 mg (0.2 mmol) of 1,2-di(2-chlorophenyl)ethyne were added, vacuumized using a Schlenk double-tube, and argon was introduced. This process was repeated three times. Under the argon atmosphere, 0.5 mL of 1,4-dioxane, 160 uL (1.0 mmol) of methyldiethoxysilane, and 132 uL (1.0 mmol) of N,N-dimethylformamide dimethyl acetal were added, and the reaction system was sealed. The temperature of the reaction system was controlled at 100°C, and the reaction was stirred for 28 hours. Saturated NH4Cl solution and ethyl acetate were added to quench the reaction, and stirring was performed for 30 minutes. The separated organic phase was concentrated, and the concentrated solution was separated by silica gel column chromatography to obtain (E)-2,3-di(2-chlorophenyl)prop-2-enal at a yield of 25%. 1 H NMR (500 MHz, CDC13) δ 9.83 (s, 1H), 7.93 (s, 1H), 7.48-7.40 (m, 2H), 7.31 (td, J = 7.8, 1.7 Hz, 1H), 7.29-7.17 (m, 2H), 7.06 (dd, J = 7.6, 1.6 Hz, 1H), 6.97 (t, J = 7.6 Hz, 1H), 6.86 (dd, J = 7.9, 1.3 Hz, 1H). 13 C NMR (126 MHz, CDC13) δ 192.34, 146.48, 141.30, 135.23, 133.70, 132.43, 132.20, 131.17, 131.12, 130.21, 129.94, 129.90, 127.21, 126.64.

[0041] Example 10: Preparation of (Z)-2,3-di(thiophen-2-yl)prop-2-enal

[0042]

[0043] Into a dry Schlenk reaction tube was added 16.2 mg (0.04 mmol) of copper carbene IMesCuCl and 38 mg (0.2 mmol) of 1,2-di(thiophen-2-yl)ethyne, vacuumed using a Schlenk double-tube, purged with argon, and 0.5 mL of 1,4-dioxane, 184 uL (1.0 mmol) of triethoxysilane, and 132 uL (1.0 mmol) of N,N-dimethylformamide dimethyl acetal were added under argon, the reaction system was sealed, and the temperature was controlled at 100°C. After stirring for 28 hours, saturated NH4Cl solution and ethyl acetate were added to quench the reaction, and stirring was continued for 30 minutes. The separated organic phase was concentrated, and the concentrated solution was separated by silica gel column chromatography to obtain (Z)-2,3-di(thiophen-2-yl)prop-2-enal in a yield of 54%. 1 H NMR (500 MHz, CDC13) δ 9.69 (s, 1H), 7.72 (s, 1H), 7.55 (d, J = 5.0 Hz, 1H), 7.43 (d, J = 5.0 Hz, 1H), 7.37 (d, J = 3.5 Hz, 1H), 7.21-7.12 (m, 1H), 7.04 (dd, J = 8.0, 4.0 Hz, 2H). 13 C NMR (126 MHz, CDC13) δ 191.95, 144.23, 137.80, 135.32, 133.10, 132.32, 131.99, 129.06, 128.48, 127.82, 127.38.

[0044] Example 11: Preparation of (E)-2-phenylbut-2- enal

[0045]

[0046] Into a dry Schlenk reaction tube was added 16.2 mg (0.04 mmol) of carbene copper IMesCuCl, vacuumed using a Schlenk double-tube, argon was introduced, and this was repeated three times. Under argon, 0.5 mL of 1,4-dioxane, 25 uL (0.2 mmol) of 1-phenylpropyne, 184 uL (1.0 mmol) of triethoxysilane, and 132 uL (1.0 mmol) of N,N-dimethylformamide dimethyl acetal were added, the reaction system was sealed, the temperature of the reaction system was controlled at 100°C, and the reaction was stirred for 28 hours. After the reaction, saturated NH4Cl solution and ethyl acetate were added to quench the reaction, and the mixture was stirred for 30 minutes. The separated organic phase was concentrated, and the concentrated solution was separated by silica gel column chromatography to obtain (E)-2-phenylbut-2-enal with a yield of 30%. 1 H NMR (500 MHz, CDCI3) δ 9.62 (s, 1 H), 7.38 (m, 3H), 7.21-7.14 (m, 2H), 6.85 (q, J = 7.1 Hz, 1 H), 2.01 (d, J = 7.1 Hz, 3H). 13 C NMR (126 MHz, CDCI3) δ 193.66, 151.37, 145.16, 132.40, 129.61, 128.37, 128.07, 16.10.

Claims

1. A method for copper-catalyzed synthesis of α,β-unsaturated aldehyde compounds, comprising the following steps: Carbene copper catalyst and alkyne of general formula 1 were added to a dry Schlenk reaction tube. The tube was evacuated using a Schlenk double-row tube and purged with argon gas three times. Under argon gas purging, solvent, silane and N,N-dimethylformamide dimethyl acetal of general formula 2 were added. The reaction system was sealed and the temperature of the reaction system was controlled at 80-110°C. After stirring for 24-36 hours, saturated NH4Cl solution and ethyl acetate were added to quench the reaction. The mixture was stirred for 30 minutes, extracted, and separated. The separated organic phase was concentrated, and the concentrate was separated by silica gel column chromatography to obtain the α,β-unsaturated aldehyde compound of general formula 3. In general formulas 1 and 3, Ar is selected from aryl, and R is selected from aryl or alkyl. The silane is selected from one of (C2H5O)3SiH, (C2H5O)2CH3SiH or (C6H5)3SiH; The carbene copper catalyst is selected from one of IMesCuCl, IPrCuCl, SIMesCuCl, or SIPrCuCl; The solvent is selected from 1,4-dioxane, toluene, or n-hexane.

2. The method for copper-catalyzed synthesis of α,β-unsaturated aldehyde compounds according to claim 1, characterized in that... The molar ratio of alkyne 1:N,N-dimethylformamide dimethyl acetal 2:silane:copper carbene is 1.0:5.0~8.0:5.0~8.0:0.1~0.2.

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