Synthesis of Chiral δ-Lactones via a Catalytic Hetero-Diels-Alder Reaction

Significance

The direct hetero-Diels-Alder reaction between a variety of unsaturated acid chlorides 1 and aldehydes 2 was achieved with a bifunctional Lewis acid-Lewis base catalytic system. The reaction provided a range of unsaturated δ-lactones with high enantioselectivity. The electron-poor aromatic aldehydes generally showed better conversions, although electron-rich aldehydes still gave high ee.