Dithiocinnamates, methyl

Nitriles can be used as starting material for the bisdithioesters (62 n = 4, 5, lO), whereas the derivatives with shorter chain lengths (62 n = l-3), as well as methyl dithiocinnamate (63), are accessible from /VA -disubstituted thioamides via the corresponding imidothioate iodides. Methyl di-thioacrylate (65), the simplest unsaturated dithioester, was prepared by flash vacuum thermolysis of a precursor dithioester (64), which had been obtained from the corresponding nitrile (equation 64). It can be isolated as a red monomeric compound at 77 K but dimerizes rapidly at room temperature. The p,7-unsaturated isoprene derivative (66) and the methyl 2-arylpropanedithioates (67) were prepared from phenyl isothiocyanate and used as educts for syntheses of lavandulal and ar-curcumene. Also ethyl furane 3-carbodithioate (68), as prepared from the nitrile, has found application in syntheses of the natural products egona ketone and ar-turmerone. ... 

Methyl dithiocinnamate was obtained in low yield from styrylmagnesium bromide by reaction with CSj and methylation with Mel, and in better yield by bw-temperature thiolysis of the thioimidate (117). At room temperature the thiolysis was complicated by addition of HjS to give the saturated sulphide analogous to (114). The dithiocinnamate dimerizes reversibly, by [4 + 2]cyclo-addition, to form a product that was assigned the structure (118) on n.m.r. evidence. 

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