A GENERAL SYNTHETIC ROUTE TO 4-SUBSTITUTED-2,2'-BITHIOPHENES

A new synthetic route to 4-substituted-2,2'-bithiophenes has been deve loped utilizing 3-bromo-2,2'-bithiophene (1). Formation of the bithien yllithium adduct via halogen-metal exchange was found to be problemati c and resulted in complex mixtures of products. The Grignard reagent o f 1 can be obtained easily via the ''entrainment'' method, allowing th e production of 4-substituted-2,2'-bithiophenes (where substituent = o ctyl, hydroxyethyl, hydroxymethyl, carboxy, carbomethoxy, acetoxyethyl , and acetoxymethyl).