Organocatalytic Asymmetric Synthesis of Functionalized 3,4‐Dihydropyran Derivatives

Organocatalysis can control both the chemo-, diastereo- and enantioselectivity in the domino addition of 1,3-cycloalkanediones to α,β-unsaturated aldehydes providing optically active 3,4-dihydropyrans (see scheme) with excellent enantioselectivies and good diastereoselectivities for a broad range of aryl- and aliphatic-substituted α,β-unsaturated aldehydes. The 3,4-dihydropyrans were transformed to various important derivatives.