Dithiolans, 1,3-Dithians, and their Selenium Analogues

Yamabe, H. Kato, and T. Yonezawa, Bull. Chem. Soc. Japan, 1971, 44, 604. 

Hayashi, M. Furukawa, Y. Fujino, T. Nakao, and S. Inoue, Chem. and Pharm. 

The conversion of active-methylene compounds into 2-alkylidene derivatives of 1,3-dithiolans by base-catalysed condensation with carbon disulphide followed by treatment with 1,2-dihalogenoalkanes has been further exemplified, and extended to the synthesis of substituted alkyl-idene derivatives of 1,3-diselenolans and 1,3-diselenans. With dimethyl malonate, carbon diselenide, and either 1,2-dibromoethane or 1,3-dibromo-propane, for example, the compounds (142) and (143), respectively, were formed. Analogously, the dithiolate anion obtained from deoxybenzoin 

Methods for the preparation of tetrathioethylenes, including cyclic derivatives of general structure (145), have been summarized, and the 

Olefins reacted with 5-phenyl-l,2,4-dithiazole-3-thiones when irradiated to give 1,3-dithiolan derivatives, cyclohexene for example giving (150), which on acid hydrolysis unexpectedly gave (151). The m-fusion of the rings in (151) was established by its conversion into cyclohexene on treatment with triethyl phosphite. Olefins with electron-withdrawing substituents did not react with 5-phenyl-l,2,4-dithiazole-3-thione, suggesting that free-radical intermediates, and not 1,3-dipolar intermediates, were involved in the initial addition. The hitherto unknown l,3-dithiolan-4-thione system has been synthesized cyclohexane-1,1-dithiol reacted 

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