Asymmetric aziridination with chiral allyl aminosulfoxonium ylides:synthesis of alkenyl aziridine carboxylates and palladium-catalyzed E,trans/E,cis-isomerization of an alkenyl aziridine

摘要

Chiral cyclic and acyclic allyl aminosulfoxonium ylides have been generated from aminosulfoxonium-substituted beta,gamma-unsaturated alpha-amino acids(method A)and 1-alkenyl aminosulfoxonium salts(method B)upon treatment with DBU.Their application to the asymmetric aziridination of N-tert-butyl-sulfonyl imino ester,generated either in situ(method A)or externally added(method B),gave the corresponding alkenyl aziridine carboxylates with medium to high diastereoselectivity and enantio-selectivity.A highly stereoselective Pd(0)-catalyzed isomerization of an E,trans-configured alkenyl aziridine methanol derivative to its E-cis-isomer is described,which proceeded with retention of the double bond configuration.