Synthesis of pyrazole analogues of isoaptazepine

Abstract
The synthesis of the novel tetracyclic rings 5 and 6 is described starting from 4‐cyano‐1‐methyl‐5(1H‐pyrrol‐1‐yl)‐1H‐pyrazole and its 3‐(1H‐pyrrol‐1‐yl)‐ isomer, respectively. The pathway employed is based on a one‐pot double annelation reaction involving the transformation of 13 into the required tetracyclic derivative 16. Lithium aluminum hydride/sulfuric acid reduction of the last compound furnished 5. A similar way was used for the synthesis of 6 by cyclization of 20.