Enantioselective Binaphthophosphepine-Promoted [3+2] Annulations of N-Ts- and N-DPP-Imines with Allenoates and 2-Butynoates

✍ Scribed by Nathalie Pinto; Nicolas Fleury-Brégeot; Angela Marinetti

• Publisher: John Wiley and Sons
• Year: 2008
• Tongue: English
• Weight: 251 KB
• Volume: 2009
• Category: Article
• ISSN: 1434-193X
• DOI: 10.1002/ejoc.200800598

✦ Synopsis

Abstract

The use of binaphthophosphepine 1a as a catalyst for the [3+2] cyclisation between allenoates or 2‐butynoates andimines was investigated. The effects of the imine protecting group on both the catalytic activity and enantioselectivity were determined by comparing the behaviour of N‐tosyl‐ and N‐DPP‐imines. The N‐DPP‐imines displayed lower reactivity, but afforded the desired pyrrolines in higher enantiomeric excess (73–92 % ee). The DPP protecting group was removed from the final pyrrolines under mild conditions to afford the corresponding secondary amines. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)