Synthesis of Chiral α-Mercapto-β-acylamido Esters via One-Pot Asymmetric Hydrosilylation-transacylation of α-cylthio-β-Enamino Esters

Chiral alpha-mercapto-beta-amino acid derivatives are highly significant for the development of new synthetic methodology and pharmaceutics. Until now, only a few catalytic asymmetric transformations for the synthesis of optically active alpha-mercapto-beta-aminoacid derivatives have been developed. In continuation of our ongoing research on asymmetric hydrosilylation, herein we report a one-pot asymmetric hydrosilylation-transacylation of N-unprotected alpha-acylthio-beta-enamino esters by employing a chiral picolinamide Lewis base as a catalyst. The reactions afforded a wide variety of alpha-mercapto-beta-acylamido esters with good yields (up to 99%) in good diastereoselectivities (> 20:1 d.r.) and moderate to good enantioselectivities (up to 86% ee). Furthermore, the absolute configuration of one product was determined and the configurations of other products were assigned by analogy. Finally, based on the absolute configuration of the product, a mechanism was proposed.