Our previous studies have shown vinyl sulfoxonium salts (α,β-unsaturated sulfoxonium salts) to be excellent Michael acceptors for the synthesis of 3,4-trans-γ-lactones. Investigation of chiral tetramines (Koga amines) as ligands for the reaction of lithium enediolates (derived from 2-arylacetic acids) with vinyl sulfoxonium salts resulted in γ-lactones being formed in moderate to good yields (up to 71%), with good diastereoselectivity in many cases (dr up to 10:1), and with moderate to high enantioselectivity (up to 91% ee). A change in the sense of diastereoselectivity from favoring the trans-isomer (in the absence of Koga amine) to favoring the cis-isomer was observed when a Koga tetramine was employed. As a result, stereodivergency through use of variations on the protocol was facilitated. Proposed models to rationalize diastereoselectivity and enantioselectivity will be presented. More recently, our group has begun explorations using vinyl phosphonium salts as Michael acceptors for analogous reactions. Details of reaction development and substrate scope will be presented.

Asymmetric synthesis of γ-lactones and related chiral building blocks through reaction of enediolates with vinyl onium salts

253rd National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.