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.
A highly efficient methodology of asymmetric epoxidation based on a novel chiral sulfur ylide
A new type of chiral sulfur ylides has been synthesized and their reactivities against carbonyl compounds tested, showing a high degree of stereoselectivity in the formation of trans epoxy amides under very mild reaction conditions.