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■ Reactions of Elemental Sulfur and Selenium with Some Asetylenic Compounds. Formation of Thiophenes and Selemophenes

Juzo Nakayama, Rie Yomoda, and Masamatsu Hoshino

*Department of Chemistry, Faculty of Science, Saitama University, Saitama, Saitama 338-8570, Japan

Abstract

The reaction o f 3-butyn-2-one with elemental sulfur at 205-215 °C in benzene in a stainless autoclave afforded 2,4- and 2,5-diacetylthiophenes in 43% and 22% yields, respectively. Under similar conditions, the reaction with elemental selenium gave 2,4-and 2,5-diacetylselenophenes in 32% and 29% yields, respectively. Diphenylacetylene reacted with sulfur and selenium to produce tetraphenylthiophene (78%) and tetraphenylselenophene (38%, respectively. The reaction of di(2-thienyl)acetylene with sulfur provided tetra(2-thienyl)thiophene in 57% yield. The reaction of dimethyl acetylenedicarboxylate with sulfur in the presence of diphenylacetylene afforded 2,3-bis(methoxycarbonyl)-4,5-diphenylthiophene (29%) and tetrakis(methoxycarbonyl)thiophene (15%). On the basis of these results, the mechanism for the formation of thiophenes and selenophenes is disccused.