DMAP-Catalyzed 4+2 Cycloaddition of α,β-Unsaturated Carboxylic Acids with Ketones for Synthesis of α, β-Unsaturated δ-Lactones

摘要

The DMAP-catalyzed [4+2] cycloaddition of a,β-unsaturated carboxylic acids with ketones furnishing a,β-unsaturated δ-lactones in good yields (up to 80％) is described,which is the first example of remote γ-C(sp3)-H activation of a,β-unsaturated carboxylic acids facilitated by DMAP,a pyridine-based catalyst.