Synthesis of 1,4,5,6-tetrahydropyrazolo[3,4-d]pyrido[3,2-b]azepine

✍ Scribed by J. Donald Albright; Xuemei Du

• Publisher: Journal of Heterocyclic Chemistry
• Year: 2000
• Tongue: English
• Weight: 434 KB
• Volume: 37
• Category: Article
• ISSN: 0022-152X
• DOI: 10.1002/jhet.5570370107

✦ Synopsis

Abstract

The synthesis of 7,8‐dihydro‐5(6__H__)‐quinolinone (3) from commercially available 3‐amino‐2‐cyclohexen‐1‐one (1) and 3‐(dimethylamino)acrolein (4) in 23% yield avoids the preparation of propynal (2). Conversion of 5‐(4‐methylphenylsulfonyl)‐6,7,8,9‐tetrahydro‐5__H__‐pyrido[3,2‐b]azepine (12) to 6‐(4‐methylphenylsulfonyl)‐1,4,5,6‐tetrahydropyrazolo[3,4‐d]pyrido[3,2‐b]azepine (24) is described. Removal of the N‐(4‐methylphenylsulfonyl) group with 40% sulfuric acid in acetic acid gave the tricyclic azepine 26. Application of a similar series of reactions to 5‐(4‐nitrobenzoyl)‐6,7,8,9‐tetrahydro‐5__H__‐pyrido[3,2‐b]‐azepine (13) afforded 6‐(4‐nitrobenzoyl)‐1,4,5,6‐tetrahydropyrazolo[3,4‐d]pyrido[3,2‐b]azepine (25).