Reactions of acetylenes, possessing bulky alkyl substituents, with S2Cl2. Unexpected formation of alpha-oxothioketones, thiirene 1-oxides, and 1,2-dithietes

The reaction of di-t-butylacetylene with S2Cl2, followed by purification wi th silica-gel column chromatography, gave 2,2,5,5-tetramethyI-4-oxo-3-hexan ethione (4a) (37%) and 2,3-di-t-butylthiirene I-oxide (5a) (10%), which wer e formed by hydrolysis of the initial product, 2,3-di-t-butyl-2,3-dichloroe pisulfide (3a). The same work-up of the reaction mixture of di(1-adamantyl) acetylene with S2Cl2 provided 2-oxoethanethione (4b) (4-33%), thiirene 1-ox ide (5b) (8-27%) and 1,2-dithiete (9b) (3-21%). The reaction of 2,2,5,5,6,6 ,9,9-octamethyl-3,7-decadiyne (Ic) with S2Cl2 furnished a 4H,5H-thiepin (12 ) as the sole product in 99% yield. (C) 2000 Elsevier Science Ltd. All righ ts reserved.