Cyclopenta-1,2-dithioles and cyclopenta-1,2-thiazines from new molecular rearrangements

Abstract

The cyclobutanone oxime 6 reacts with disulfur dichloride to give two unexpected 10π pseudoazulenes in low yield: the dark blue cyclopenta-1,2-dithiole 7 and the orange cyclopenta-1,2-thiazine 8; the benzo derivative 14 of this oxime gives the analogous benzo product 15 together with the methylene indene 16 in high yield; mechanisms based on abnormal Beckman rearrangements are proposed for the formation of all of these products.