Anomalous Ring Cleavage of 1,3-Dithiole- and 1,3-Diselenole-2-thiones under the Cross-Coupling Conditions Using Triethyl Phosphite

The ring cleavage of 4,5-ethylenedioxy-1,3-dithiole- and -1,3-diselenole-2-thiones, followed by the reaction with 4,5-bis (methoxycarbonyl)-1,3-diselenole-2-one took place under the phosphite-mediated cross-coupling conditions to afford 2-thioxo- and 2-(selenoxomethylidene)-1,3-diselenoles. The structure of 4,5-bis(methoxycarbonyl)-2-(thioxoalkylidene)-1,3diselenole was confirmed by X-ray analysis.