A Highly Stereoselective Synthesis of Glycidic Amides Based on a New Class of Chiral Sulfonium Salts: Applications in Asymmetric Synthesis

A new type of chiral sulfonium salts that are characterized by a bicyclic system has been designed and synthesized from α‐amino acids. Their corresponding ylides, which were prepared by basic treatment of the sulfonium salts, reacted smoothly with a broad array of simple and chiral aldehydes to provide trans‐epoxy amides in reasonable to very good yields and excellent stereoselectivities (>98 %). The obtained epoxy amides were found to be useful as synthetic building blocks. Thus, they were reduced into their corresponding epoxy alcohols and subjected to oxirane‐ring‐opening reactions with different types of nucleophiles. Un nuevo tipo de sales de sulfonio quirales, caracterizadas por contener un sistema bicíclico, ha sido diseñado y sintetizado desde α‐amino ácidos. Sus correspondientes iluros, preparados por tratamiento básico de las sales de sulfonio, reaccionaron suavemente con una amplia gama de aldehidos simples y quirales para dar las epoxiamidas trans en rendimientos desde razonables a muy buenos, y estereoselectividad excelente estimada en más de un 98 %. Las epoxiamidas obtenidas probaron ser útiles building blocks. Así, éstas fueron reducidas a sus correspondientes epoxialcoholes y, además, fueron sometidas a reacciones de apertura del anillo de oxirano con diferentes tipos de nucleófilos. Salty but sweet: Chiral sulfonium salts that featured a bicyclic system reacted with carbonyl compounds to afford epoxy amides with excellent stereoselectivity. A wide array of 1,2‐functionalized systems was prepared by oxirane‐ring‐opening reactions (see scheme).