Lewis acid-Lewis base-catalysed enantioselective addition of alpha-ketonitriles to aldehydes
2007 (English)In: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 349, no 3, 364-372 p.Article in journal (Refereed) Published
Additions of structurally diverse alpha-ketonitriles to aromatic and aliphatic prochiral aldehydes yielding highly enantioenriched acylated cyanohydrins were achieved using a combination of a titanium salen dimer and an achiral or chiral Lewis base. In most cases high yields and high enantioselectivities were observed. The ee was moderate in the initial part of the reaction but increased over time. This could be avoided, and higher ees obtained, by keeping the titanium complex, in the presence or absence of aldehyde and ketonitrile, at -40 degrees C prior to the addition of the Lewis base. A mechanism initiated by nucleophilic attack of the tertiary amine at the carbonyl carbon atom of the ketonitile is supported by C-13 labelling experiments.
Place, publisher, year, edition, pages
2007. Vol. 349, no 3, 364-372 p.
Lewis acids; Lewis bases; O-acylcyanohydrins; Salen; Titanium
IdentifiersURN: urn:nbn:se:kth:diva-6916DOI: 10.1002/adsc.200600365ISI: 000244268900015ScopusID: 2-s2.0-33947594481OAI: oai:DiVA.org:kth-6916DiVA: diva2:11763
QC 201008092007-03-222007-03-222010-08-09Bibliographically approved