Asymmetric synthesis of epoxides from aldehydes mediated by (+)-(2R,5R)-2,5-dimethylthiolane
- 1 January 1999
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 1
- No. 6,p. 731-736
- https://doi.org/10.1039/a807623e
Abstract
Nonracemic epoxides were prepared by reaction of (+)-(2R,5R)-2,5-dimethylthiolane, benzyl bromide and a mineral base with an aldehyde. Various parameters (solvent, base, aldehyde, sulfide) have been investigated. These studies led to the optimisation of a practical and simple procedure. Acetonitrile or tert-butyl alcohol were used in the presence of water and potassium or sodium hydroxide at room temperature. These conditions gave 87–93% yields with aromatic or branched aliphatic aldehydes and enantiomeric excesses ranged from 66 to 96%. Kinetic studies and stereochemical analyses have been carried out and a transition state was suggested to rationalize the observed stereochemistry.Keywords
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