Über die Umlagerung von Benzo[ b ]‐1, 4‐thiazepinen und 1, 4‐Thiazepinen

The rearrangement of differently substituted 1, 4‐thiazepines under various reaction conditions has been investigated. 2‐Phenyl‐4‐methylthio‐benzo [ b ]‐1, 4‐thiazepine ( 3 ) and 2‐phenyl‐benzo [ b ]‐1, 4‐thiazepine‐4 (5 H )‐thione ( 2 ) extrude sulfur under the catalytic influence of bases and rearrange into 2‐methylthio‐4‐phenyl‐quinoline ( 4 ) and 4‐phenyl‐thiocarbostyril ( 6 ) respectively. Under the same conditions, 2‐phenyl‐4‐methylthio‐2, 3‐dihydro‐benzo [ b ]‐1, 4‐thiazepine ( 11 ) rearranges to 2‐styryl‐benzothiazine ( 12 ), whereas the dioxide 18 shows no tendency to rearrange. 2,7‐Diphenyl‐hexahydro‐1,4‐thiazepine‐5‐one( 19 ) could be converted into 2‐styryl‐5‐phenyl‐2‐thiazoline ( 20 ) by treatment with polyphosphoric acid. The possible mechanisms of these rearrangements are discussed.