A highly enantioselective [4+2] cycloaddition involving aldehydes and β,γ-unsaturated-α-keto esters
作者:Nanda Kumar Katakam、Yejin Kim、Allan D. Headley
DOI:10.1016/j.tetasy.2017.09.019
日期:2017.11
A stereoselective inverse electron demand oxo-Diels-Alder reaction involving electron poor dienes (gamma-aryl-beta,gamma-unsaturated-alpha-keto ester) and electron rich dienophiles has been studied. These cycloaddition reactions are extremely useful for the construction of O-, N-, S-centered heterocyclic compounds, which are routinely used in both synthetic organic and medicinal chemistry. The [4+2] hetero cycloaddition reactions involving various aldehydes and beta,gamma-unsaturated-alpha-keto esters were carried out in which three different types of substituted proline catalysts were examined. For these reactions, high selectivities (enantiomeric excess 93-98%) were obtained using catalyst 3. Due to the bulkiness of catalyst 3, compared to the other catalysts tested, it is more efficient at catalyzing these type reactions. (C) 2017 Elsevier Ltd. All rights reserved.