An Efficient Synthesis of 3 H-Pyrrolo[3,2- d]pyrimidin-4(5 H)-one Derivatives via an Iminophosphorane.

The iminophosphorane ( 3), obtained from reaction of ethyl 3-amino-4-cyano-1-phenyl-1 H-pyrrole-2-carboxylate ( 2) with triphenylphosphine, hexachloroethane, and triethylamine, reacted with aromatic isocyanates to give carbodiimides ( 4). Further reaction of 4 with various amines, phenols, or ROH to give 2,3,5,7-tetrasubstituted 3 H-pyrrolo[3,2- d]pyrimidine-4(5 H)-ones ( 6) in satisfactory yields in the presence of catalytic amount of sodium alkoxide or solid potassium carbonate. [ABSTRACT FROM AUTHOR]