Direct Catalytic Asymmetric Conjugate Addition of Saturated and Unsaturated Thioamides

Direct catalytic asymmetric conjugate
addition of thiolactams to
α,β-unsaturated thioamides was efficiently promoted by
a soft Lewis acid/hard Brønsted base cooperative catalyst in
a highly stereocontrolled manner. Thioamide functionality was crucial
to promote both the efficient enolization of thiolactam pronucleophiles
and the subsequent stereoselective conjugate addition to α,β-unsaturated
thioamides. Differential manipulation of the two thioamide functionalities
of the product highlights the synthetic utility of the present catalytic
system.