Reactions of stable alpha-chlorosulfanyl chlorides with C=S-functionalized compounds

Abstract

The smooth reaction of 3-chloro-3-(chlorosulfanyl)-2,2,4,4-tetramethylcyclobutanone (3) with 3,4,5-trisubstituted 2,3-dihydro-1H-imidazole-2-thiones 8 and 2-thiouracil (10) in CH2Cl2/Et3N at room temperature yielded the corresponding disulfanes 9 and 11 (Scheme 2), respectively, via a nucleophilic substitution of Cl- of the sulfanyl chloride by the S-atom of the heterocyclic thione. The analogous reaction of 3-cyclohexyl-2,3-dihydro-4,5-diphenyl-1H-imidazole-2-thione (8b) and 10 with the chlorodisulfanyl derivative 16 led to the corresponding trisulfanes 17 and 18 (Scheme 4), respectively. On the other hand, the reaction of 3 and 4,4- dimethyl-2-phenyl-1,3-thiazole-5(4H)-thione (12) in CH2Cl2 gave only 4,4-dimethyl-2-phenyl-1,3-thiazol-5(4H)-one (13) and the trithioorthoester derivative 14, a bis-disulfane, in low yield (Scheme 3). At -78°, only bis(1-chloro-2,2,4,4-tetramethyl-3-oxocyclobutyl)polysulfanes 15 were formed. Even at -78°, a 1 : 2 mixture of 12 and 16 in CH2Cl2 reacted to give 13 and the symmetrical pentasulfane 19 in good yield (Scheme 5). The structures of 11, 14, 17, and 18 have been established by X-ray crystallography.