A method for synthesizing a beta(z) type alkenyl silane compound

Abstract

This invention discloses a β ( Z A method for synthesizing alkenylsilanes of type [Cp*Rh( μ -Cl)3RhCp*][X](Cp*:pentamethylcyclopentadienyl; X:Cl ‑ BF4 ‑ CF3SO3 ‑ Complex-catalyzed hydrosilylation of alkynes enables highly regioselective and stereoselective synthesis. β ( Z () type alkenylsilane compounds. The complex catalyst used in this invention can be recovered and reused by adding a weakly polar solvent to the reaction product and then filtering; at the same time, this invention overcomes the... β ( Z The synthesis of alkenylsilanes is difficult due to their thermodynamic instability. However, the reaction conditions are mild and the operation is simple, making them promising for future applications.

Description

TECHNICAL FIELD

[0001] The present application relates to a synthesis method of a beta(Z) type alkenyl silane compound. BACKGROUND

[0002] Organosilanes are a class of very important synthetic unit compounds [a) Langkopf, E.; Schinzer, D. Chem. Rev. 1995, 95, 1375-1408], which have a wide range of applications in the fields of synthetic chemistry, medicinal chemistry and material chemistry research. Alkenylsilanes are a class of common organosilanes, which form alkenyl ion synthons by connecting the carbon-carbon double bond through the silane substituent. At present, the synthesis of alkenylsilanes through the hydrosilylation of alkynes is the most atom-economical synthesis method [a) Angew. Chem. Int. Ed., 2004, 43, 2749]. The hydrosilylation of terminal alkynes produces three different stereoisomers of beta(E), beta(Z) and alpha alkenylsilanes. Among them, it is difficult to synthesize beta(Z) type alkenylsilanes with high regioselectivity and high stereoselectivity due to the presence of thermodynamic instability.

[0003] In the current research, the beta(Z) type hydrosilylation of alkynes usually uses metal complexes with platinum (Pt), ruthenium (Ru), rhodium (Rh), iridium (Ir) noble metals as active centers as catalysts [a) Carmona E. et al. Chem. Commun., 2015, 51, 17008; b) Ojima I. et al. Organometallics, 1990, 9, 3127; c) Saito S. et al. Org. Lett., 2017, 19, 5204; d) Oro L. A. et al. Chem. Commun., 2012, 48, 9480], but the recycling of the catalyst has not been reported. SUMMARY

[0004] The problem to be solved by the present application is to provide a synthesis method of beta(Z) type alkenylsilanes, which is a method for synthesizing beta(Z) type alkenylsilanes with high regioselectivity and high stereoselectivity by catalyzing the hydrosilylation of alkynes with [Cp*Rh(μ-Cl)3RhCp*][X] (Cp*: pentamethylcyclopentadienyl; X: Cl - , BF4 - , CF3SO3 - ) complex.

[0005] The present application is realized by the following technical solutions:

[0006] The application discloses a synthesis method of beta(Z) type alkenyl silane, which comprises the following steps: taking acetylene as a reaction substrate, taking silane as a silicon source, taking complex [Cp*Rh(mu-Cl)3RhCp*][X] as a catalyst, and reacting at 20-40 DEG C for a period of time to obtain beta(Z) type alkenyl silane, wherein the molar ratio of acetylene, silane and [Cp*Rh(mu-Cl)3RhCp*][X] is 1:1:0.01-0.02.

[0007] Further, the structural formula of the acetylene is R 1 is any one of alkyl, aryl, heteroaryl and substituted aryl. The structure of the silane is wherein R 2 , R 3 and R 4 are any one of alkyl, aryl and alkoxy. The structural formula of the [Cp*Rh(mu-Cl)3RhCp*][X] complex is X is any one of Cl, BF4 - and CF3SO3 - .

[0008] Further, the synthesis method disclosed by the application involves an organic solvent, and the organic solvent is selected from any one of chloroform, dichloromethane, acetonitrile, toluene, tetrahydrofuran, benzene, carbon tetrachloride, diethyl ether, petroleum ether and n-hexane.

[0009] Further, in the synthesis method disclosed by the application, the reaction temperature is 20-40 DEG C, and the reaction temperature is preferably 20-30 DEG C. The reaction time is 1-2 hours.

[0010] Further, the synthesis method disclosed by the application further comprises the following steps: after the reaction is completed, a weak polar solvent is added to the reaction system, and then filtration is carried out to obtain a filtrate and a solid. The obtained solid is the catalyst, and the catalyst can be reused after being dried. The filtrate obtained by filtration is separated through recrystallization, thin layer chromatography, column chromatography or reduced pressure distillation to obtain the alkenyl silane product.

[0011] Further, the weak polar solvent is selected from at least one of n-hexane, n-pentane, n-heptane and n-octane. The adding amount of the weak polar solvent is 5-10 times of the volume of the reaction solvent.

[0012] Further, the synthesis reaction needs to be carried out under the protection of an inert atmosphere.

[0013] The application has the following beneficial effects:

[0014] The method of the present application provides a method for synthesizing beta(Z) type alkenyl silane compounds by the hydrosilylation reaction of acetylene with [Cp*Rh(mu-Cl)3RhCp*][X] as catalyst. Compared with the prior art, the method is suitable for various types of acetylene and silane, the reaction condition is mild, the operation is simple, and the atomic economy can reach 100%. The present application overcomes the difficulty of the thermodynamic instability of beta(Z) type alkenyl silane and the difficulty of its synthesis. In addition, the complex catalyst used in the method of the present application can be recovered and reused by adding a weak polar solvent to the reaction product and filtering. Because the metal complex catalyst is selected, the method of the present application has good functional group compatibility, high regioselectivity and high stereoselectivity, and the content of beta(Z) type alkenyl silane compounds in the synthesized product can reach more than 90 mol%, usually 91-99 mol%. DETAILED DESCRIPTION

[0015] The method of the present application is an effective method for synthesizing beta(Z) type alkenyl silane. The method is to synthesize beta(Z) type alkenyl silane with high regioselectivity and high stereoselectivity with the complex [Cp*Rh(mu-Cl)3RhCp*][X] as catalyst.

[0016] The molecular general formula of the alkenyl silane compound synthesized by the method of the present application is R 1 Any one of alkyl, aryl, heteroaryl and substituted aryl can be selected, and X is any one of Cl - , BF4 - , CF3SO3 - . R 2 may be any one of alkyl, aryl and alkoxy.

[0017] The alkenyl silane compound of the present application is obtained by reacting terminal alkyne and tertiary silane with [Cp*Rh(mu-Cl)3RhCp*][X] as catalyst in an organic solvent system. The reaction mechanism can be represented by the following formula:

[0018]

[0019] The general structure of the acetylene is: wherein R 1 is as described above; and the general structure of the catalyst is

[0020]

[0021] In the present application, the [Cp*Rh(mu-Cl)3RhCp*][X] complex catalyst can be selected from commercially available products or prepared according to conventional knowledge in the art.

[0022] In this invention, the [Cp*Rh(μ-Cl)3RhCp*][X] complex catalyst was synthesized according to the method reported in the literature Rybinskaya M.I., Kudinov AR, Kaganovich VS, J. Organometal. Chem., 1983, 246, 279.

[0023] The method of the present invention will be described in more detail below with reference to specific embodiments.

[0024] Example 1

[0025] Under the protection of an inert gas, phenylacetylene ( 1.5 mmol), triethylsilane (HSiEt3, Et is ethyl, 1.5 mmol), [Cp*Rh(μ-Cl)3RhCp*][BF4]( 0.03 mmol) was added to a dry Schlenk flask, and the mixture was reacted at 20 °C for 1 hour using chloroform (5 mL) as the reaction solvent. The product was treated with n-hexane (40 mL) and then filtered. The resulting solid was used as a catalyst and could be reused after drying. The filtrate was separated by column chromatography to obtain (Z)-1-triethylsilyl-2-phenylethylene.

[0026] A colorless oily substance, containing 98 mol% of β(Z)-configured alkenylsilane. 1 H NMR (400MHz, CDCl3, ppm): 7.46 (d, J=15.2Hz, 1H, CH=CHSiEt3), 7.23-7.33 (m, 5H, Ph-CH), 5.75 (d, J=15.2Hz, 1H, CH=CHSiEt3), 0.87 (t, J=7.9Hz, 9H, SiEt3-CH3), 0.53 (q, J=7.9Hz, 6H, SiEt3-CH2).

[0027] Example 2

[0028] Under the protection of an inert gas, phenylacetylene ( 1.5 mmol), triphenylsilane (HSiPh3, where Ph is phenyl, 1.5 mmol), [Cp*Rh(μ-Cl)3RhCp*][BF4]( 0.03 mmol) was added to a dry Schlenk flask, and the mixture was reacted at 30 °C for 2 hours using chloroform (5 mL) as the reaction solvent. The product was treated with n-hexane (40 mL) and then filtered. The resulting solid was used as a catalyst and could be reused after drying. The filtrate was separated by column chromatography to obtain (Z)-1-triphenylsilyl-2-phenylethylene.

[0029]

[0030] White solid, the product contains 99 mol% β(Z)-configured alkenylsilane. 1 H NMR (400MHz, CDCl3, ppm): 7.76 (d, J = 15.4Hz, 1H, CH = CHSiPh3), 7.57 (d, J = 6.8Hz, 6H, Ph-CH), 7.31-7.38 (m, 9H, Ph-CH), 7.1 9 (d, J = 7.2 Hz, 2H, Ph-CH), 7.05 (t, J = 6.8 Hz, 1H, Ph-CH), 6.95 (t, J = 6.8 Hz, 2H, Ph-CH), 6.38 (d, J = 15.4 Hz, 1H, CH = CHSiPh3).

[0031] Example 3

[0032] Under the protection of an inert gas, phenylacetylene ( 1.5 mmol), triethoxysilane (HSi(OEt)3, OEt is ethoxy, 1.5 mmol), [Cp*Rh(μ-Cl)3RhCp*][BF4]( 0.03 mmol) was added to a dry Schlenk flask, and the mixture was reacted with chloroform (5 mL) at 20 °C for 1.5 hours. The product was treated with n-hexane (40 mL) and then filtered. The resulting solid was used as a catalyst and could be reused after drying. The filtrate was separated by column chromatography to obtain (Z)-1-triethoxysilyl-2-phenylethylene.

[0033]

[0034] A colorless oily substance, containing 94 mol% β(Z)-configured alkenylsilane. 1 H NMR (400MHz, CDCl3, ppm): 7.58 (d, J = 7.2Hz, 2H, Ph-CH), 7.43 (d, J = 15.5Hz, 1H, CH = CHSi (OEt) 3), 7.28-7.36 (m, 3H, Ph-C H), 5.59 (d, J=15.5Hz, 1H, CH=CHSi(OEt)3), 3.76 (q, J=7.0Hz, 6H, Si(OEt)3-CH2), 1.15 (t, J=7.0Hz, 9H, Si(OEt)3-CH3).

[0035] Example 4

[0036] Under the protection of an inert gas, p-methylphenylacetylene ( 1.5 mmol), triethylsilane (HSiEt3, Et = ethyl, 1.5 mmol), [Cp*Rh(μ-Cl)3RhCp*] [BF4] (0.03 mmol) were added to a dry Schlenk flask with chloroform (5 mL) as the reaction solvent and reacted at 30 °C for 1.5 h. The product was treated with n-hexane (40 mL) and filtered. The solid catalyst was dried and reused. The filtrate was separated by column chromatography to obtain (Z)-1-triethylsilyl-2-(4-methylphenyl)ethene. 0.03 mmol) were added to a dry Schlenk flask with chloroform (5 mL) as the reaction solvent and reacted at 30 °C for 1.5 h. The product was treated with n-hexane (40 mL) and filtered. The solid catalyst was dried and reused. The filtrate was separated by column chromatography to obtain (Z)-1-triethylsilyl-2-(4-methylphenyl)ethene.

[0037]

[0038] Colorless oil, the content of the β(Z) configuration alkenylsilane in the product was 99 mol%. 1 H NMR (400 MHz, CDC13, ppm): 7.45 (d, J = 15.2 Hz, 1H, CH=CHSiEt3), 7.22 (d, J = 7.9 Hz, 2H, Ph-CH), 7.14 (d, J = 7.9 Hz, 2H, Ph-CH), 5.74 (d, J = 15.2 Hz, 1H, CH=CHSiEt3), 2.38 (s, 3H, 4-Ph-CH3), 0.92 (t, J = 7.9 Hz, 9H, SiEt3-CH3), 0.61 (q, J = 7.9 Hz, 6H, SiEt3-CH2).

[0039] Example 5

[0040] p-Chlorophenylacetylene (1.5 mmol), triethylsilane (HSiEt3, Et = ethyl, 1.5 mmol), [Cp*Rh(μ-Cl)3RhCp*] [BF4] (0.03 mmol) were added to a dry Schlenk flask with chloroform (5 mL) as the reaction solvent and reacted at 30 °C for 2 h. The product was treated with n-hexane (40 mL) and filtered. The solid catalyst was dried and reused. The filtrate was separated by column chromatography to obtain (Z)-1-triethylsilyl-2-(4-chlorophenyl)ethene. 1.5 mmol), triethylsilane (HSiEt3, Et = ethyl, 1.5 mmol), [Cp*Rh(μ-Cl)3RhCp*] [BF4] (0.03 mmol) were added to a dry Schlenk flask with chloroform (5 mL) as the reaction solvent and reacted at 30 °C for 1.5 h. The product was treated with n-hexane (40 mL) and filtered. The solid catalyst was dried and reused. The filtrate was separated by column chromatography to obtain (Z)-1-triethylsilyl-2-(4-methylphenyl)ethene.

[0041]

[0042] ​A colorless oily substance containing 95 mol% of β(Z)-configured alkenylsilane. ¹H NMR (400 MHz, CDCl₃, ppm): 7.38 (d, J = 15.2 Hz, 1H, CH = CHSiEt₃), 7.28 (d, J = 8.4 Hz, 2H, Ph-CH), 7.20 (d, J = 8.4 Hz, 2H, Ph-CH), 5.80 (d, J = 15.2 Hz, 1H, CH = CHSiEt₃), 0.87 (t, J = 7.9 Hz, 9H, SiEt₃-CH₃), 0.54 (q, J = 7.9 Hz, 6H, SiEt₃-CH₂).

[0043] Example 6

[0044] Under the protection of an inert gas, 1-heptyne ( 1.5 mmol), triethylsilane (HSiEt3, Et is ethyl, 1.5 mmol), [Cp*Rh(μ-Cl)3RhCp*][BF4]( 0.03 mmol) was added to a dry Schlenk flask, and the reaction was carried out at 20 °C for 1.5 hours using chloroform (5 mL) as the reaction solvent. The product was treated with n-hexane (40 mL) and then filtered. The resulting solid was used as a catalyst and could be reused after drying. The filtrate was separated by column chromatography to obtain (Z)-1-triethylsilyl-1-heptene.

[0045]

[0046] A colorless oily substance, containing 91 mol% of β(Z)-configured alkenylsilane. 1 H NMR (400MHz, CDCl3, ppm): 6.38 (dt, J = 14.3Hz, 7.3Hz, 1H, CH = CHSiEt3), 5.39 (d, J = 14.1Hz, 1H, CH = CHSiEt3), 2.09 (q, J = 7.3Hz, 2H, CH2CH = CH), 1.34-1.4 3(m,2H,CH3CH2),1.28-1.33(m,4H,CH2CH2CH2CH2),0.95(t,J=7.9Hz,9H,SiEt3-CH3),0.90(t,J=6.3Hz,3H,CH3CH2),0.61(q,J=7.9Hz,6H,SiEt3-CH2).

Claims

1. A method for synthesizing a β(Z) type alkenylsilane, comprising the following steps: taking an alkyne as a reaction substrate, taking silane as a silicon source, taking a complex [Cp*Rh(μ-Cl)3RhCp*][X] as a catalyst, and reacting in an organic solvent at 20-40°C for a period of time to obtain a β(Z) type alkenylsilane; after the reaction, adding a weak polar solvent to the reaction system, then filtering to obtain a filtrate and a solid, and the solid being the catalyst; filtering the filtrate, and separating by recrystallization, thin layer chromatography, column chromatography or vacuum distillation to obtain the alkenylsilane product. The molar ratio of the alkyne, the silane and the complex [Cp*Rh(μ-Cl)3RhCp*][X] is 1:1:0.01-0.

02. The structure of the alkyne is R 1 is any one of alkyl, aryl, heteroaryl; The silane has a structural formula of wherein R 2 , R 3 , R 4 is any one of alkyl, aryl, alkoxy; The complex [Cp*Rh(μ-Cl)3RhCp*][X] has a structural formula of X is Cl - , BF4 - , CF3SO3 - , or any one of them.

2. The method of synthesis according to claim 1, wherein, The organic solvent is selected from any one of chloroform, dichloromethane, acetonitrile, toluene, tetrahydrofuran, benzene, carbon tetrachloride, diethyl ether, petroleum ether and n-hexane.

3. The method of synthesis according to claim 1, wherein, The reaction temperature is 20-30°C.

4. The method of synthesis according to claim 1, wherein, The reaction time is 1-2 hours.

5. The method of synthesis according to claim 1, wherein, The weak polar solvent is selected from at least one of n-hexane, n-pentane, n-heptane and n-octane.

6. The method of synthesis according to claim 1 or 5, characterized in that, The weak polar solvent is added in an amount of 5-10 times the volume of the reaction solvent.

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