Synthetic applications of 3,4-bis(trimethylsilyl)thiophene: unsymmetrically 3,4-disubstituted thiophenes and 3,4-didehydrothiophene

A novel method for the synthesis of unsymmetrically 3,4-disubstituted thiophenes was developed based on the intermolecular thiazole-alkyne Diels-Alder reactions involving 3,4-bis(trimethylsilyl)thiophene. The synthetic strategy was characterized by the formation of the [2+2]- and [4+2]-cycloaddition adducts of 3,4-didehydrothiophene via 1,3-dipolar cycloadditions. Furthermore, the synthetic process was characterized by 3,4-bromothiophene modification and intermolecular thiazole-alkyne Diels-Alder reactions with 3,4-bis(trimethylsilyl)thiophene.