The reaction thiiranes with isothiocyanates

• Published in: Nippon Kagakukai shi (1972) Vol. 1989; no. 1; pp. 63 - 67
• Main Authors: TAGUCHI, Yoichi, SHIBUYA, Isao, SUHARA, Yasuo
• Format: Journal Article
• Language: English
• Published: Tokyo Japan Science and Technology Agency 1989
• ISSN: 0369-4577; 2185-0925
• DOI: 10.1246/nikkashi.1989.63

The reaction of thiirane with methyl isothiocyanate in DMF gave N-methyl-1, 3-dithiolan-2-imine [1] and 3-methyl-1, 3-thiazolidine-2-thione [2]. The ratio of [1] to [2]. was largely increased by the addition of tertiary amine such as triethylamine, and decreased by addition of the salts such as tetraethylammonium bromide or lithium chloride. In the reaction of thiirane with phenyl isothiocyanate, the main product was N-phenyl-1, 3-dithiolan-2-imine even using lithium chloride catalyst at 120°C, though 3-phenyl-1, 3-thiazolidine-2thione was also formed in 12% yield. Reactions of substituted thiiranes such as methylthiirane with methyl isothiocyanate gave 1, 3-dithiolane-2-thiones in addition to the compounds corresponding to [1] and [2]. Although there are two possible structures concerning the compound corresponding to [2], it was determined to be 5-substituted compound by means of 13C-NMR spectroscopy. The mechanism was presumed as follows : the first step was the formation of 1, 3-dithiojanes and followed by the reaction of 1, 3-dithiolanes with thiirane to give 1, 3-thiazdlidine-2-thiones.