Silicone-Supported Cinchona Alkaloid Derivatives as Insoluble Organocatalysts in the Enantioselective Dimerization of Ketenes

✍ Scribed by Damiano Cancogni; Alessandro Mandoli; Ravindra P. Jumde; Dario Pini

• Book ID: 102829139
• Publisher: John Wiley and Sons
• Year: 2012
• Tongue: English
• Weight: 682 KB
• Volume: 2012
• Category: Article
• ISSN: 1434-193X
• DOI: 10.1002/ejoc.201101320

✦ Synopsis

Abstract

A straightforward procedure is presented for the covalentimmobilization of ester and silyl ether derivatives of the__Cinchona__ alkaloid 10,11‐dihydroquinidine within insoluble cross‐linked silicone elastomeric films. These materials were effective heterogeneous organocatalysts in the asymmetric dimerization of ketenes, which provided chiral Weinreb β‐ketoamides in 28–83 % yield and 79–99 % ee in the course of several recycles. A productivity/enantioselectivity protocol is also proposed to better assess the relative merits of soluble and supported asymmetric catalytic systems towards process intensification.