Synthesis of (±)-Glaucine and (±)-Neospirodienone via an One-Pot BischlerNapieralski Reaction and Oxidative Coupling by a Hypervalent Iodine Reagent

✍ Scribed by Wei-Jan Huang; Om V. Singh; Chung-Hsiung Chen; Shoei-Sheng Lee

• Book ID: 102256250
• Publisher: John Wiley and Sons
• Year: 2004
• Tongue: German
• Weight: 139 KB
• Volume: 87
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.200490005

✦ Synopsis

Abstract

Condensation of 3,4‐dimethoxybenzeneethanamine (3d) and various benzeneacetic acids, i.e., 4a–e, via a practical and efficient one‐pot Bischler–Napieralski reaction, followed by NaBH~4~ reduction, produced a series of 1‐benzyl‐1,2,3,4‐tetrahydroisoquinolines, i.e., 5a–e, in satisfactory yields (Scheme 3). Oxidative coupling of the N‐acyl and N‐methyl derivatives 6a–e of the latter with hypervalent iodine ([IPh(CF~3~COO)~2~]) yielded products with two different skeletons (Scheme 4). The major products from N‐acyl derivatives 6a–c were (±)‐N‐acylneospirodienones 2a–c, while the minor was the 3,4‐dihydroisoquinoline 7. (±)‐Glaucine (1), however, was the major product starting from N‐methyl derivative 6e. Possible reaction mechanisms for the formation of these two types of skeleton are proposed (Scheme 5).