Microwave-assisted Pd(OH)2-catalyzed direct C−H arylation of free-(NH2) adenines with aryl halides

A direct C−H arylation of free-(NH2) adenines using Pd(OH)2/C (Pearlman’s catalyst) and stoichiometric amount of copper iodide under ligandless microwave activation is described. This new protocol proved to be highly effective to synthesize a variety of 8-aryladenine derivatives 3 without prior protection of the amino substituent. The arylation reaction takes place rapidly within few minutes and allows the coupling to proceed regioselectively at the 8-position with a wide range of aryl halides including aryl iodides, bromides and the less reactive aryl chlorides.