A highly enantioselective Piers-type hydrosilylation of simple ketones was successfully realized using a chiral frustrated Lewis pair of tri-tert-butylphosphine and chiral diene-derived borane as catalyst.A wide range...A highly enantioselective Piers-type hydrosilylation of simple ketones was successfully realized using a chiral frustrated Lewis pair of tri-tert-butylphosphine and chiral diene-derived borane as catalyst.A wide range of optically active secondary alcohols were furnished in 80%-99% yields with 81%-97% ee's under mild reaction conditions.展开更多
Main observation and conclusion In this work,a novel mode for the activation of N-heterocyclic carbene boranes(NHC-boranes)was developed by generating the highly reactive zwitterion species through hydride abstraction...Main observation and conclusion In this work,a novel mode for the activation of N-heterocyclic carbene boranes(NHC-boranes)was developed by generating the highly reactive zwitterion species through hydride abstraction with Lewis acid B(C_(6)F_(5))_(3) in an frustrated Lewis pairs manner.A broad range of alkenes including stilbenes,β-methylstyrenes,styrenes,and alkyl-alkenes were suitable substrates for the B(C_(6)F_(5))_(3)-catalyzed hydroboration to furnish the desired products in good to high yields.Significantly,excellent regioselectivities were obtained in some cases.Mechanistic studies indicate that the B-H bond cleavage is likely involved in the rate-determining step.In addition,an electrophilic addition of NHC-borenium cation to alkenes and the subsequent formation of carbocation are also postulated.The current work provides a promising method for the activation of stable borane adducts,which might lead to some interesting transformations in the future.展开更多
基金We are grateful for generous financial support from the National Natural Science Foundation of China (.21572231,21521002,and 21825108).
文摘A highly enantioselective Piers-type hydrosilylation of simple ketones was successfully realized using a chiral frustrated Lewis pair of tri-tert-butylphosphine and chiral diene-derived borane as catalyst.A wide range of optically active secondary alcohols were furnished in 80%-99% yields with 81%-97% ee's under mild reaction conditions.
基金the financial support from the National Natural Science Foundation of China(Nos.21871269 and 21521002).
文摘Main observation and conclusion In this work,a novel mode for the activation of N-heterocyclic carbene boranes(NHC-boranes)was developed by generating the highly reactive zwitterion species through hydride abstraction with Lewis acid B(C_(6)F_(5))_(3) in an frustrated Lewis pairs manner.A broad range of alkenes including stilbenes,β-methylstyrenes,styrenes,and alkyl-alkenes were suitable substrates for the B(C_(6)F_(5))_(3)-catalyzed hydroboration to furnish the desired products in good to high yields.Significantly,excellent regioselectivities were obtained in some cases.Mechanistic studies indicate that the B-H bond cleavage is likely involved in the rate-determining step.In addition,an electrophilic addition of NHC-borenium cation to alkenes and the subsequent formation of carbocation are also postulated.The current work provides a promising method for the activation of stable borane adducts,which might lead to some interesting transformations in the future.
