The rearrangement of 2‐benzyl‐5‐mesitoyl‐3(2H)‐isothiazolone to 2‐phenyl‐6‐mesitoyl‐3,4‐dihydro‐1,3‐thiazin‐4(2H)‐one

Abstract

Abstract2‐Benzyl‐5‐mesitoyl‐3(2H)‐isothiazolone (8) has been prepared from 3‐mesitoylpropionic acid (5). Reaction of the isothiazolone 8 with sodium ethoxide in ethanol has been found to yield an isomeric rearranged compound, which was characterized as 2‐phenyl‐6‐mesitoyl‐3,4‐dihydro‐1,3‐thiazin‐4(2H)‐one (9). This unexpected rearrangement is attributed to the abstraction of a benzylic hydrogen atom from the N‐benzyl group, followed by ring enlargement through cleavage of the isothiazolone SN bond.