Unusual reaction of a substituted benzothiazoline with sulphuryl chloride: formation of a 2,2′-(ethane-1,2-diylidene)bis-1,4-benzothiazine dye
Abstract
3-Acetyl-2-ethyl-2-phenylbenzothiazoline (1) reacts at room temperature with SO2Cl2 to give, in 67% yield, the dye (2), by way of the 1,4-benzothiazine (3) arising by a new ring expansion reaction.