Asymmetric Organocatalytic Synthesis of Highly Substituted Cyclohexenols by Domino Double-Michael Reactions of 1-Hydroxy-1,4-dien-3-ones and 2-Alkylidenemalononitriles

A facile asymmetric synthetic protocol to afford 2,6-disubstituted 4-hydroxy-3-oxocyclohex-3-ene-1,1-dicarbonitriles has been developed through the domino double-Michael addition of 1,5-disubstituted 1-hydroxy-1,4-dien-3-ones to 2-alkylidenemalononitriles using quinine as the catalyst. This simple organocatalytic domino process provides access to various highly functionalized chiral 4-hydroxy-3-oxocyclohex-3-enes, which are the rarely reported chiral diketo cyclohexane analogues, in moderate-to-good yields and enantioselectivities and with excellent diastereoselectivities (>25:1 dr).