Organic Disulfides and Related Substances. 46. Derivatives of 2-(Benzylsulfinyl)ethanethiol

Article abstract of DOI:10.1021/jo00360a035

In a further study of the little known class of mercapto sulfoxides and their derivatives 2-(benzylsulfinyl)-ethanethiol (9a) could be kept only for minutes at ca. 25 deg C in CH2Cl2, but the key intermediate, S-<2-(benzylsulfinyl)ethyl> p-toluenethiosulfonate (17), was quite stable; 17 was prepared by reaction of 2-(benzylsulfinyl)ethyl chloride (7) with sodium p-toluenethiosulfonate (10).Reaction of the thiosulfonate 17 with Na2S under usual conditions gave 2-(benzylsulfinyl)ethyl disulfide (8), rather than the expected trisulfide (11), but a two-phase reaction with dilute solutions protected the trisulfide and led to 11 (69percent yield); aqueous Na2S converted 11 to 8.Reaction of 17 with a thiol, RSH, under usual conditions gave only the symmetrical disulfide, RSSR, but unsymmetrical disulfides could be obtained at -70 deg C .Solutions of 12-16 resisted change for 21-66 h in the dark, for 19-66 h in ambient light, for 7-11 h in refluxing EtOAc (dark), and for 19-36 h in refluxing EtOH (dark); in UV light, however, reaction began in 7-20 min.The order of increasing resistance to change, under all conditions, was 12 < 16 < 13 < 14 < 15.The di- (8) and trisulfide (11) were much more resistant than any of the unsymmetrical disulfides under all conditions.Neighboring group effects of the -S- and -S(O)- functions appeared to play a role in several instances.