Vinylogous Michael Addition of α,β-Unsaturated γ-Butyrolactams to Enones

Significance

A direct organocatalytic asymmetric vinylogous Michael addition of α,β-unsaturated γ-butyrolactam 2 with α,β-unsaturated ketones 1 is reported. With trifunctional catalyst 4 in combination with an acid co-catalyst 5 (N-Boc-l-Trp), the corresponding Michael adducts 3 could be obtained in high yields and excellent enantio- and diastereoselectivities. This transformation showed a broad substrate scope with regard to the enones, and aromatic, aliphatic, cyclic and acylic vinyl ketones can all be converted with excellent stereoselectivity. The synthetic utility of the addition products was exemplified by the authors with the manipulation on the α,β-unsaturated γ-butyrolactam moiety like dihydroxylation, conjugate addition, and reduction.