aldolisation reaction of lithium ester enolates with chiral α,β-epoxyaldehydes 2a–2f has been investigated. The reaction proceeds with diastereofacial preference in favour of the anti isomer (anti:syn ≈ 4:1) and can be greatly enhanced in the case of cis α,β-epoxy-aldehydes 2a–2c by a synergic effect of temperature and enolate excess (anti:syn 13:1). The Felkin-Ahn model can explain the results obtained
Stereoselective reactions of α,β-epoxy-aldehydes; the formation of “chelation controlled” products
作者:Shouming Wang、Graham P. Howe、Ravinderjit S. Mahal、Garry Procter
DOI:10.1016/s0040-4039(00)92086-0
日期:1992.6
Treatment of the α,β-epoxy-aldehydes (1) and (2) with Lewis acids followed by in situ reaction with carbon nucleophiles produces halohydrins of the products of “chelationcontrolled” addition to the aldehyde with high diastereoselectivity; The regiochemistry of epoxide opening is determined by choice of Lewis acid.