EXTENSION OF THE HECK REACTION TO THE ARYLATION OF ACTIVATED THIOPHENES

The direct arylation of activated thiophenes was accomplished in moder ate to good yields using a Heck-type reaction with the mixture of Pd(O Ac)(2) and n-Bu4NBr as a catalytic system. This new arylation method i s applied to different derivatives and has proved to be compatible wit h sensitive functional groups. Furthermore, the substituent nature and position on the thiophene moiety influence the cross coupling. In par ticular the substitution is regiospecific when the heterocycle is subs tituted at position 2 with an electron withdrawing group. (C) 1998 Els evier Science S.A. All rights reserved.