Upon irradiation with light at 2537 Å 2-alkyl-2-thiazolines (1) underwent rearrangement to N- alkenylthioamides (2 and 3) as the major pathway and fragmentation to a nitrile and an episulphide as the minor one. Evidence is provided for the intermediary formation of a valence bond isomer, N-thioacylaziridine, followed by its photochemical transformation into N-alkenylthioamides.
