1,2-diaminobenzimidazoles : Selective inhibitors of nitric oxide synthase derived from aminoguanidine

The synthesis of a series of novel 1,2-diaminobenzimidazoles is described. While the parent compound 4a is a weak, modestly selective inhibitor of the induced isoform of nitric oxide synthase (both mouse and human), a small structural change led to compound 5, a highly selective inhibitor of neuronal enzyme.