Dearomatizing Disrotatory Electrocyclic Ring Closure of Lithiated N-Benzoyloxazolidines

Abstract

Loss of aromaticity ensues when N-benzoyl oxazolidines are lithiated and undergo a 6π disrotatory electrocyclization (see scheme). The stereochemistry of the cyclization shows it to be a new example of an electrocyclic ring closure. The cis-tricyclic products epimerize to their more stable trans diastereoisomers in aqueous acid.