Enantioselective NHC-catalysed redox [4+2]-hetero-Diels-Alder reactions using α-aroyloxyaldehydes and unsaturated ketoesters

James E. Taylor, Alyn T. Davies, James J. Douglas, Gwydion Churchill, Andrew D. Smith

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)


N-Heterocyclic carbene (NHC)-catalysed redox [4+2]-hetero-Diels-Alder reactions of α-aroyloxyaldehydes with either β,γ-unsaturated α-ketoesters or α,β-unsaturated γ-ketoesters generates substituted syn-dihydropyranones in good yield with excellent enantioselectivity (up to >99:1 er). The product diastereoselectivity is markedly dependent upon the nature of the unsaturated enone substituent. The presence of either electron-neutral or electron-rich aryl substituents gives excellent diastereoselectivity (up to >99:5 dr), while electron-deficient aryl substituents give reduced diastereoselectivity. In these cases, the syn-dihydropyranone products are more susceptible to base-promoted epimerisation at the C(4)-position under the reaction conditions, accounting for the lower diastereoselectivity obtained.
Original languageEnglish
Pages (from-to)355-366
JournalTetrahedron: Asymmetry
Issue number2
Early online date19 Jan 2017
Publication statusPublished - 15 Feb 2017


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