A synthesis of 2-aryl-3-hydroxybenzothiophenes and analogs by the base promoted cyclization of N-phenyl-2-(benzylthio)benzamides
摘要:
A new methodology is described for the synthesis of 3-hydroxybenzothiophenes, 3-hydroxypyridothiophenes, and the corresponding selenophene analogs by the base promoted cyclization of corresponding 2-(benzylthio)arenecarboxanilides. The starting materials are readily prepared using directed metalation of the corresponding arenecarboxanilides.
and α-acetammido benzyl carbanions by means of a two-step sequence involving highly diastereoselective α-C-alkylation with alkyl halides followed by displacement of the sulfinyl residue (which can be recovered and recycled) by a hydroxyl, a chlorine or an acetamido, respectively, under non-oxidative Pummererconditions. The scope and limits of the method, including a stereoselective version of the