Organocatalytic Asymmetric Sulfa-Michael Addition of Thiols to α,β-Unsaturated Hexafluoroisopropyl Esters: Expeditious Access to (R)-Thiazesim
摘要:
A highly efficient organocatalytic asymmetric SMA reaction of hexafluoroisopropyl alpha,beta-unsaturated esters has been developed. Introducing electron-withdrawing hexafluoroisopropyl ester is crucial to enhancing the electrophilicity of unsaturated esters as SMA acceptors. The catalytic system performs well over a broad scope of alpha,beta-unsaturated esters and diversified thiols and provides facile access to (R)-thiazesim in a one-pot protocol.
Enantiospecific on-water bromination: a mild and efficient protocol for the preparation of alkyl bromides
作者:Francesco Alletto、Mauro F. A. Adamo
DOI:10.1039/d0gc02855j
日期:——
Herein we report the first example of an on-water enantiospecific synthesis of alkylbromides. This procedure allowed the conversion of secondary activated alkyl sulphides to benzylic alkylbromides, which were obtained in 80–99% yields. The reaction carried out on enantio-pure sulphides provided the corresponding bromides in high yields and enantioselectivity (up to 92% ee; 94% es) at room temperature