N-Heterocyclic Carbene-Mediated Enantioselective Addition of Phenols to Unsymmetrical Alkylarylketenes
作者:Carmen Concellón、Nicolas Duguet、Andrewâ D. Smith
DOI:10.1002/adsc.200900538
日期:2009.11
Chiral N-heterocyclic carbenes (NHCs) mediate the enantioselectiveaddition of 2-phenylphenol to unsymmetricalalkylarylketenes, delivering α-alkyl-α-arylacetic acid derivatives with good levels of enantiocontrol (up to 84% ee). Enantiodivergent stereochemical outcomes are observed using 2-phenylphenol and benzhydrol in the NHC-promoted esterification reaction using a triazolium precatalyst derived
Carbene-Catalyzed Dynamic Kinetic Resolution of Carboxylic Esters
作者:Xingkuan Chen、Jacqueline Zi Mei Fong、Jianfeng Xu、Chengli Mou、Yunpeng Lu、Song Yang、Bao-An Song、Yonggui Robin Chi
DOI:10.1021/jacs.6b00406
日期:2016.6.15
Carbene-catalyzed reaction of carboxylicesters has the potential to offer effective synthetic solutions that cannot be readily achieved by using the more conventional aldehyde-type substrates. Here we report the first carbene-catalyzed dynamic kinetic resolution of α,α-disubstituted carboxylicesters with up to 99:1 er and 99% yield. The present study clearly illustrates the unique power of carbene-catalyzed
Asymmetric esterification of ketenes catalyzed by an N-heterocyclic carbene
作者:Xiao-Na Wang、Hui Lv、Xue-Liang Huang、Song Ye
DOI:10.1039/b815139c
日期:——
The chiral N-heterocycliccarbene precursor 2, derived from L-pyroglutamic acid, was found to be an efficient precatalyst for the enantioselective esterification of alkylarylketenes with benzhydrol to give the corresponding esters in good yields with good to high enantioselectivities (up to 95% ee).