2-Thioxo-1,3-thiazepan-4-ones, a novel class of cyclic dithiourethanes with a 7-membered ring system

Article abstract of DOI:10.1002/jhet.5570360509

Reaction of isothiocyanates 1 with γ-thiobutyrolactone (2) in alkaline medium yielded 4-thiocarbamoylthiobutyric acids 3 after acidification, which could be cyclized to the 2-thioxo-1,3-thiazepan-4-ones 6. Additional reactions were observed with the formation of 6t from p- phenylenediisothiocyanate (1s) and with the formation of 6w from benzyl isothiocyanate (1t). 3-Acetylamino-γ-thiobutyrolactone (7) could also be used in this reaction yielding the butyric acid derivatives 3u-3w. Cyclization yielded the 1,3-thiazepane derivatives 6x, y which rearranged under ring contraction to the 1,3-thiazinanes 8a, b.