Synthesis of pyrrolo[2,1-a]phthalazines by 1,3-dipolar cycloaddition of phthalazinium N-ylides with alkenes in the presence of tetrakis-pyridine cobalt (II) dichromate

✍ Scribed by Jian Zhou; Yuefei Hu; Hongwen Hu

• Publisher: Journal of Heterocyclic Chemistry
• Year: 2000
• Tongue: English
• Weight: 308 KB
• Volume: 37
• Category: Article
• ISSN: 0022-152X
• DOI: 10.1002/jhet.5570370524

✦ Synopsis

Abstract

We describe here, for the first time, that 1‐cyano‐3‐benzoyl‐1,2,3,10b‐tetrahydropyrrolo[2,1‐a]phthalazine (8), prepared by 1,3‐dipolar cycloaddition of 2‐phenacyl phthalazinium bromide (6a) with acrylonitrile (7a), can be aromatized by tetrakis‐pyridine cobalt (II) dichromate (TPCD) to give 1‐cyano‐3‐benzoylpyrrolo[2,1‐α]phthalazine (9a) in good yield. Furthermore, a general and convenient one‐pot procedure for preparation of pyrrolo[2,1‐α]phthalazines (9a‐p) was developed by 1,3‐dipolar cycloaddition of phthala zinium N‐ylides (6a‐c) with alkenes (7a‐g) in the presence of TPCD.