Abstract
The 3,3‐dichloro‐2,2,4,4‐tetramethylcyclobutanethione (4b) was prepared from the parent diketone by successive reaction with PCl~5~ and Lawesson reagent in pyridine. This new thioketone 4b was transformed into 1‐chlorocyclobutanesulfanyl chloride 5 and chloro 1‐chlorocyclobutyl disulfide 9 by treatment with PCl~5~ and SCl~2~, respectively, in chlorinated solvents (Schemes 1 and 2). These products reacted with S‐ and P‐nucleophiles by substitution of Cl^−^ at the S‐atom; e.g., the reaction with 4b yielded the di‐ and trisulfides 6b and 11, respectively. Surprisingly, only pentasulfide 12 was formed in the reaction of 9 with thiobenzophenone (Scheme 3). In contrast to 5 and 9, the corresponding chloro 1‐chlorocyclobutyl trisulfide 13 could not be detected, but reacted immediately with the starting thioketone 4b to give the tetrasulfide 14 (Scheme 4). Oxidation of 4b with 3‐chloroperbenzoic acid (__m__CPBA) yielded the corresponding thione oxides (= sulfine) 15, which underwent 1,3‐dipolar cycloadditions with thioketones 3a and 4b (Scheme 5). Furthermore, 4b was shown to be a good dipolarophile in reactions with thiocarbonylium methanides (Scheme 6) and iminium ylides (= azomethine ylides; Scheme 7). In the case of phenyl azide, the reaction with 4b gave the symmetrical trithiolane 25 (Scheme 8).