Enhanced activity of enantioselective (salen)Mn(III) epoxidation catalysts through supramolecular complexation

✍ Scribed by Gregory A. Morris; SonBinh T. Nguyen; Joseph T. Hupp

• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 121 KB
• Volume: 174
• Category: Article
• ISSN: 1381-1169
• DOI: 10.1016/s1381-1169(01)00165-0

✦ Synopsis

Salen)Mn(III) catalysts show increased turnover numbers in the catalytic asymmetric epoxidation of conjugated olefins upon addition of bulky Lewis acids (LA) such as zinc tetraphenylporphyrin (ZnTPP). Up to 3-fold increase in total catalytic activity and at least a 20-fold increase in catalyst stability was observed with a (salen)Mn catalyst bearing pendant 5,5 -bis-pyridyl groups. This latter enhancement is primarily attributed to formation of a coordination triad, which provides steric protection for the catalyst from bimolecular decomposition. Supramolecular complex formation enhanced the catalyst's stability without compromising its enantioselectivity.