The catalytic potential of carbon nucleophiles has seldom been disclosed due to their reactivity toward carbon electrophiles to form stable carbon-carbon bonds,which are too strong to be cleaved for the expected catal...The catalytic potential of carbon nucleophiles has seldom been disclosed due to their reactivity toward carbon electrophiles to form stable carbon-carbon bonds,which are too strong to be cleaved for the expected catalytic cycles. We have developed an efficient catalytic cyanosilylation of carbonyl compounds with an in situ generated alkene/phosphine adduct,which is tuned not to couple with a carbonyl compound or an electron-deficient alkene under the reaction conditions when its nucleophilicity is trans-lated into catalytic activity. In the presence of 3 mol% of methyl acrylate and 3 mol% of triphenylphosphine,a broad range of alkyl,alkenyl,and aryl ketones and aldehydes undergo cyanosilylation reaction with trimethylsilyl cyanide at room temperature to yield structurally diversified cyanohydrin silyl ethers in excellent yields. By using methyl acrylate/triphenylphosphine as a highly effective nucleophilic catalyst system for the cyanosilylation of carbonyl compounds,this study demonstrates a new concept for the development of useful organocatalysis utilizing the nucleophilicity of alkene/phosphine adducts generated in situ.展开更多
The mechanisms of gold（I）-catalyzed cycloaddition of 1-（1-alkynyl） cyclopropyl ketones with nucleophiles have been investi- gated using density functional theory calculations at the B3LYP/6-31G （d, p） level of t...The mechanisms of gold（I）-catalyzed cycloaddition of 1-（1-alkynyl） cyclopropyl ketones with nucleophiles have been investi- gated using density functional theory calculations at the B3LYP/6-31G （d, p） level of theory. A polarizable continuum model （PCM） has been established in order to evaluate the effects of solvents on the reactions. The results of the calculations indicate that the first step of the catalytic cycle is the cyclization of the carbonyl oxygen onto the triple bond which forms a new and stable resonance structure of an oxonium ion and a carbocation intermediate. The subsequent ring expansion step results in the formation of the final product and regeneration of the catalyst. Furthermore, the regioselectivity and effect of substituents has been discussed, including an analysis of energy, bond length, and natural bond orbital （NBO） charge distributions in the rate-determining step. Our computational results are consistent with earlier experimental observations.展开更多
基金supported by the National Natural Science Foundation of China (20732006 and 20672105) and the Chinese Academy of Sciences
文摘The catalytic potential of carbon nucleophiles has seldom been disclosed due to their reactivity toward carbon electrophiles to form stable carbon-carbon bonds,which are too strong to be cleaved for the expected catalytic cycles. We have developed an efficient catalytic cyanosilylation of carbonyl compounds with an in situ generated alkene/phosphine adduct,which is tuned not to couple with a carbonyl compound or an electron-deficient alkene under the reaction conditions when its nucleophilicity is trans-lated into catalytic activity. In the presence of 3 mol% of methyl acrylate and 3 mol% of triphenylphosphine,a broad range of alkyl,alkenyl,and aryl ketones and aldehydes undergo cyanosilylation reaction with trimethylsilyl cyanide at room temperature to yield structurally diversified cyanohydrin silyl ethers in excellent yields. By using methyl acrylate/triphenylphosphine as a highly effective nucleophilic catalyst system for the cyanosilylation of carbonyl compounds,this study demonstrates a new concept for the development of useful organocatalysis utilizing the nucleophilicity of alkene/phosphine adducts generated in situ.
基金supported by the Natural Science Foundation of Gansu Province (10710RJZA114)
文摘The mechanisms of gold（I）-catalyzed cycloaddition of 1-（1-alkynyl） cyclopropyl ketones with nucleophiles have been investi- gated using density functional theory calculations at the B3LYP/6-31G （d, p） level of theory. A polarizable continuum model （PCM） has been established in order to evaluate the effects of solvents on the reactions. The results of the calculations indicate that the first step of the catalytic cycle is the cyclization of the carbonyl oxygen onto the triple bond which forms a new and stable resonance structure of an oxonium ion and a carbocation intermediate. The subsequent ring expansion step results in the formation of the final product and regeneration of the catalyst. Furthermore, the regioselectivity and effect of substituents has been discussed, including an analysis of energy, bond length, and natural bond orbital （NBO） charge distributions in the rate-determining step. Our computational results are consistent with earlier experimental observations.
