Asymmetric synthesis: From transition metals to organocatalysis

Kocovsky, P. and Malkov, A. V. (2008) Asymmetric synthesis: From transition metals to organocatalysis. Pure and Applied Chemistry, 80(5), pp. 953-966. (doi:10.1351/pac200880050953)

Full text not currently available from Enlighten.

Publisher's URL: http://dx.doi.org/10.1351/pac200880050953

Abstract

Umpolung in the allylation reaction is discussed with examples drawn from transition-metal-catalyzed allylic substitution (with the allylic unit acting as an electrophile) and Lewis base-catalyzed allylation of aldehydes with allyltrichlorosilane (with the allyl acting as a nucleophile). Iridium-catalyzed electrophilic allylation of O-nucleophiles has been employed in our new approach to C-nucleoside analogs, where the C-O bond (rather than C-C) was constructed stereospecifically. Variation of the absolute configuration in the starting segments allowed the synthesis of all four combinations of D/L-α/ β-ribosides. In the nucleophilic allylation of aldehydes, chiral pyridine-type N-oxide catalysts are presented, in particular QUINOX and METHOX, and the intriguing behavior of QUINOX is discussed. Here, the π-π interactions between the substrate aldehyde and the catalyst are suggested to rationalize the experimental observations. Good correlation between the calculated energies for the transition states and the experimentally observed enantioselectivities has been obtained.

Item Type:Articles
Keywords:(PI-ALLYL)palladium complexes, absolute configuration, aldehydes. allylation. allylic substitution, allyltrichlorosilane, analogs, aromatic-aldehydes, asymmetric synthesis, behaviorm bond, catalyst, catalysts, catalyzed, allylic, alkylation, chiral, lewis-bases, co enantioselective, allylation, energies, energy, homoallylic alcohols, Ir-catalyzed, metal, metals, methox n-oxide, n-oxides, organic-synthesis, organocatalysis, oxidative addition, quinox, ribosides, state substitution, syn-anti dichotomy transition, transition, metals, transition-metal-catalyzed, transition-metals, transition-state, umpolung unit
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Malkov, Dr Andrei and Kocovsky, Professor Pavel
Authors: Kocovsky, P., and Malkov, A. V.
College/School:College of Science and Engineering > School of Chemistry
Journal Name:Pure and Applied Chemistry
Journal Abbr.:Pure Appl. Chem.
Publisher:Walter de Gruyter
ISSN:0033-4545
ISSN (Online):1365-3075
Published Online:01 January 2009

University Staff: Request a correction | Enlighten Editors: Update this record

Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
384741Organocatalysts in asymmetric reactions mediated by silicon reagentsPavel KocovskyEngineering & Physical Sciences Research Council (EPSRC)GR/T27051/01Chemistry