Stereoretentive Addition of<i>N</i>-<i>tert</i>-Butylsulfonyl-α-Amido Silanes to Aldehydes, Ketones, α,β-Unsaturated Esters, and Imines
作者:Tsuyoshi Mita、Keisuke Saito、Masumi Sugawara、Yoshihiro Sato
DOI:10.1002/asia.201600270
日期:2016.5.20
Enantioenriched N‐tert‐butylsulfonyl‐α‐amido silanes were successfully reacted with aldehydes, ketones, imines, and α,β‐unsaturated esters in the presence of a sub‐stoichiometric amount of CsF (0.5 equiv) in 1,2‐dimethoxyethane (DME) at −20 °C to afford the corresponding coupling products with up to 89 % enantiospecificity in a retentive manner.
Synthesis of Arylglycine and Mandelic Acid Derivatives through Carboxylations of α-Amido and α-Acetoxy Stannanes with Carbon Dioxide
作者:Tsuyoshi Mita、Masumi Sugawara、Hiroyuki Hasegawa、Yoshihiro Sato
DOI:10.1021/jo202597p
日期:2012.3.2
Incorporation reactions of carbon dioxide (CO2) with N-Boc-alpha\-amido and a-acetoxy stannanes were developed using CsF as a mild tin activator. Monoprotected alpha-amido stannanes could be used, and the corresponding arylglycine derivatives were obtained in moderate-to-high yields under 1 MPa (10 atm) of CO2 pressure. alpha-Acetoxy stannanes also underwent carboxylation to afford mandelic acid derivatives in excellent yields under ambient CO2 pressure. Both transformations enabled the synthesis of alpha-tertiary and alpha-quaternary carboxylic acid derivatives. In addition, the chirality of (S)-N-tert-butylsulfonyl-alpha-amido stannanes was transferred with up to 90% inversion of configuration at 100 degrees C.