Formal Alkynylation and Alkenylation of α,β-Unsaturated Aldehydes

Significance

The authors report a highly stereoselective organocatalytic one-pot protocol for the alkynylation and alkenylation of α,β-unsaturated aldehydes. A prolinol derivative catalyzed conjugate addition of β-keto heterocyclic sulfones (like 1) to α,β-unsaturated aldehydes (like 2) was the first step of this transformation sequence and gave key intermediates 4 with high enantioselectivity. Without isolation adducts 4 were subsequently converted into β-alkynylated aldehydes and 3-alkenylated alcohols respectively under conditions A or B. Further transformation of the aldehyde and the alcohol functionality to other useful functional groups were also demonstrated.