Diastereoselective Conjugate Radical Additions to ~-Pyrones

Abstract

A convenient protocol for functionalization of ~-pyrones has been developed. Conjugate radical addition and tandem addition-trapping protocols allowed accessing highly substituted pyrones in a single operation with high selectivity. Different radical sources were utilized in the reaction. nOe experiments were performed to confirm the relative stereochemistry of the substituents in the conjugate addition products. Initial studies on the enantioselectivity of the reaction were carried out. Unfortunately, the catalysts chosen for the initial studies did not show any promise regarding enantioselectivity.