Electrophilic 2-Thienylselenenylation of Thiophene. Preparation of Oligo(seleno-2,5-thienylenes)

The substitution reactions of thiophene and 2-methylthiophene with the electrophilic selenenylating agent produced from the 2,2′-dithienyl diselenide by oxidation with iodobenzene diacetate involve only the α-positions and give rise to the formation of oligo(seleno-2,5-thienylenes). Products deriving from the attack at the α-positions of thiophene and 2-methylthiophene were also observed starting from the 5,5′-dimethyl-2,2′-dithienyl diselenide. The same electrophilic reagents reacted with furan and 2-methylfuran to afford a mixture of the mono- and di-substituted compounds.