Abstract
Treatment of ethyl propiolate (I) with thiourea or ammonium dithiocarbamate under neutral conditions gave diethyl cis-cis-β, β'-thioacrylate (II), stereospecifically. Analogously II was obtained from ethyl cis-β-chloroacrylate and the same reagents. II was easily converted to trans-trans-II (XII) by heating or irradiation. On the other hand, the reactions of β-substituted acetylenic acid esters (XVII a-f) with thiourea afforded the corresponding 1, 3-thiazine derivatives (XVIII a-f), unexpectedly. The reactions of propiolonitrile (XX), tetrolonitrile (XXIII) and phenylpropiolonitrile (XXV) with thiourea or ammonium dithiocarbamate afforded cis-cis-β, β'-thioacrylonitrile (XXI), cis-cis-β, β'-thiocrotononitrile (XXIV) and cis-cis-β, β'-thiocinnamonitrile (XXVI), respectively.
