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Highly Active Polymer‐Supported (Salen)Al Catalysts for the Enantioselective Addition of Cyanide to α,β‐Unsaturated Imides
Author(s) -
Madhavan Nandita,
Weck Marcus
Publication year - 2008
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.200700491
Subject(s) - catalysis , chemistry , enantioselective synthesis , cyanide , norbornene , polymer , synergistic catalysis , conjugate , organic chemistry , polymer chemistry , combinatorial chemistry , polymerization , mathematical analysis , mathematics
In this contribution, we describe polymer‐supported ( R,R )‐(salen)AlCl complexes that were immobilized on poly(norbornene)s and display excellent activities and enantioselectivies as catalysts for the 1,4‐conjugate addition of cyanide to α,β‐unsaturated imides. These supported catalysts could be recycled up to 5 times without compromising catalyst activities or selectivities. Furthermore, the catalyst loadings could be reduced from 10–15 mol%, the common catalyst loadings for non‐supported (salen)Al catalysts, to 5 mol%, a decrease of metal content by 50–66%, without lowering product yields or enantioselectivities. Kinetic studies indicated that the polymer‐supported catalysts are significantly more active than their corresponding unsupported analogues, which makes this catalyst system key to a successful implementation of this catalytic transformation into the fine chemical and pharmaceutical industries.