Abstract The reaction of 3-(dimethylamino)-1-oxo-1H-naphtho [2, 1-b] pyran-2-carbaldehyde (Ia) with o-phenylenediamines or N-monosubstituted o-phenylenediamines in refluxing glacial acetic acid afforded the corresponding naphtho [1′, 2′: 5, 6] pyrano [2, 3-b][1, 5] benzodiazepin-15-(8H) ones V in very good yields. A similar result was achieved when the reaction was carried out in refluxing pyridine, using N-monosubstituted o- ...