Relationship between Dominant Conformation and Diastereoselectivity of O‐Acetal Formation of Saturated 2H‐3,1‐Benzothiazine‐2‐thiones

Abstract

Stereospecific formation of O‐acetals 4, 5 of the isomeric octahydro‐8a‐hydroxy‐4‐phenyl‐2H‐3,1‐benzothiazine‐2‐thiones 1–3 is reported. The stereoselectivity of the reaction is determined by the dominant conformations. During all reactions the phenyl substituent retains its equatorial position.