REACTIONS OF ELEMENTAL SULFUR AND SELENIUM WITH SOME ACETYLENIC COMPOUNDS. FORMATION OF THIOPHENES AND SELENOPHENES

Article abstract of DOI:10.3987/R-1987-08-2215

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