Domino Reaction of Arylglyoxals with Pyrazol-5-amines: Selective Access to Pyrazolo-Fused 1,7-Naphthyridines, 1,3-Diazocanes, and Pyrroles

New multicomponent domino reactions of arylglyoxals with pyrazol-5-amines have been established, providing selective access to unprecedented pyrazolo-fused 1,7-naphthyridines, 1,3-diazocanes, and pyrroles (up to 52 examples). The unreported dipyrazolo-fused 1,7-naphthyridines were regioselectively synthesized through a special double [3 + 2 + 1] heteroannulation accompanied by direct C–C formation between two electrophilic sites of arylglyoxals. The unusual [3 + 3 + 1 + 1] cyclization resulted in 20 examples of novel dipyrazolo-fused 1,3-diazocanes, whereas pyrrolo­[2,3-<i>c</i>]­pyrazoles were obtained in good yields by varying arylglyoxals <b>1</b> and pyrazol-5-amines <b>2</b> in the ratio 1:2. Mechanisms of formation of these three new types of heterocycles are also proposed