Sequential three-component synthesis of 1,4-bis[6,9-dihydro-6-oxo-9-phenyl-1 H -purin-2-yl]piperazines

Abstract

A simple one-pot efficient method for the synthesis of 1,4-bis[6,9-dihydro-6-oxo-9-phenyl-1H-purin-2-yl]piperazines by a domino three-component process involves an aza-Wittig reaction/heterocyclisation in the presence of sodium ethoxide as catalyst. Ethyl 1-phenyl-5-[(triphenylphosphoranylidene)amino]-1H-imidazole-4-carboxylate reacted with aromatic isocyanate to give carbodiimide intermediates, followed by addition of piperazines to give the corresponding guanidine intermediates. The guanidine intermediates were cyclised in the presence of a catalytic amount of sodium ethoxide to give 1,4-bis(6,9-dihydro-6-oxo-9-phenyl-1H-purin-2-yl)piperazine derivatives in good yields.