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Enantioselective and diastereoselective syntheses of cyanohydrin carbonates

Lookup NU author(s): Professor William Clegg, Dr Ross Harrington, Eisuke Ishibashi, Professor Michael North

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Abstract

A new and general synthesis of alkyl cyanoformates is presented starting from the appropriate alcohol and oxalyl chloride. This is used to prepare enantiomerically pure cyanoformates from enantiomerically pure primary and secondary alcohols. Optimal conditions for the addition of various achiral cyanoformates to aldehydes catalysed by an enantiomerically pure titanium(salen) catalyst in the presence of potassium cyanide as a cocatalyst are developed. Under these conditions, two chiral cyanoformates also reacted with aldehydes to give cyanohydrin carbonates. The stereochemistry of this process is predominantly determined by the stereochemistry of the titanium(salen) catalyst and the stereochemistry of two of the cyanohydrin carbonates was confirmed by X-ray crystallography. In a further extension of the chemistry, a homogeneous system in which the potassium cyanide/18-crown-6 complex is used as the cyanide cocatalyst has been developed and the kinetics of this reaction show that it displays first order kinetics, provided at least 2 mol % of the potassium cyanide complex are employed. © 2007 Elsevier Ltd. All rights reserved.

Publication metadata

Author(s): Belokon' YN, Clegg W, Harrington RW, Ishibashi E, Nomura H, North M

Publication type: Article

Publication status: Published

Journal: Tetrahedron

Year: 2007

Volume: 63

Issue: 39

Pages: 9724-9740

Date deposited: 14/06/2010

ISSN (print): 0040-4020

ISSN (electronic): 1464-5416

Publisher: Pergamon

URL: http://dx.doi.org/10.1016/j.tet.2007.07.016

DOI: 10.1016/j.tet.2007.07.016

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