Application of 7-endo-trig Pictet–Spengler Cyclization to the Formation of the Benzazepine Ring: Synthesis of Benzazepinoindoles

✍ Scribed by Sudhir K. Sharma; Sunil Sharma; Piyush K. Agarwal; Bijoy Kundu

• Publisher: John Wiley and Sons
• Year: 2009
• Tongue: English
• Weight: 261 KB
• Volume: 2009
• Category: Article
• ISSN: 1434-193X
• DOI: 10.1002/ejoc.200801201

✦ Synopsis

Abstract

The preparation of benzazepinoindoles, fused heterocycles with a benzazepine moiety, was accomplished through an intramolecular 7‐endo‐trig Pictet–Spengler cyclization. The precursors comprising C‐3‐ or C‐2‐linked o‐aminobenzylindoles required for the cyclization were obtained either by treating indoles with o‐nitrobenzyl bromide followed by reduction of the nitro group or by treating 2‐nitrophenylacetic acid with DCC/DMAP followed by reduction of the aryl nitro functionality. Resulting substrates 5 and 6 were then subjected to the 7‐endo‐trig Pictet–Spengler reaction with a variety of aldehydes and ketones to furnish new polycyclic structures benzazepinoindoles. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)