Individual oligomers possessing thiophenes linked by their 2-and 5-positions are conveniently prepared via 1, 3-butadiynes. These can be prepared in good yield by the Glaser symmetrical coupling of thienylacetylenes. Following the cyclization of the 1, 3- butadiyne unit into a thiophene with sodium sulfide, an oligomer possessing an odd number of thiophene rings is obtained. Oligomers with an even number of rings are accessible ...
