Isothiourea-mediated asymmetric Michael-lactonisation of trifluoromethylenones: a synthetic and mechanistic study
作者:Louis C. Morrill、James Douglas、Tomas Lebl、Alexandra M. Z. Slawin、David J. Fox、Andrew D. Smith
DOI:10.1039/c3sc51791h
日期:——
HBTM-2.1 promotes the catalytic asymmetric intermolecular Michael-lactonisation of arylacetic acids and trifluoromethylenones in the presence of pivaloyl chloride, giving C(6)-trifluoromethyldihydropyranones with high diastereo- and enantiocontrol (up to 95 : 5 dr and >99% ee) that are readily derivatised to diverse synthetic building blocks containing trifluoromethyl-stereogenicity. Kinetic studies indicate the reaction is first order with respect to both in situ formed mixed anhydride and catalyst concentration, with a primary kinetic isotope effect observed using α,α-di-deuterio 4-fluorophenylacetic acid, consistent with rate determining deprotonation of an intermediate acyl isothiouronium ion.
A Missing Link in Multisubstituted Pyrrolidines: Remote Stereocontrol Forged by Rhodium‐Alkyl Nitrene
作者:Xinxin Tang、Raj K. Tak、Hidetoshi Noda、Masakatsu Shibasaki
DOI:10.1002/anie.202212421
日期:2022.11.21
discovery together with the dearth of methods for synthesizing multisubstituted heterocycles with nonadjacent stereocenters, we report the stereoselective synthesis of remotely decorated, trisubstituted β-prolines via Rh-catalyzedC−Hamination. The present protocol addresses the prevalent limitations associated with substituted pyrrolidines.