Transformation of Thiophene Derivatives into Compounds of Other Series

Abstract

Abstract Thiophene derivatives undergo some reductive transformations giving rise to numerous aliphatic, carbocyclic as well as to other heterocyclic systems. One type of these transformations includes as the first step the action of a reducing agent on thiophene compounds giving dihydro- or tetrahydrothiophene derivatives, and subsequent cleavage of the latter with another agent. While the use of catalytic hydrogenation in the thiophene series is essentially limited, there are now other methods - electrochemical reduction and ionic hydrogenation-leading to dihydro- and tetrahydrothiophenes, respectively. The other approach which is more widely used includes formally one-step reductive cleavage of thiophene rings with the scission of one or both C-S bonds. The most important methods of this type are reductive desulfurization with Raney nickel and the reductive cleavage by the action of alkali metals in liquid ammonia. In these processes thiophene plays the role of a “building block” the aromatic nature of...