Study on Hetero-Diels-Alder Reactions of alpha,beta-Unsaturated Trifluoromethyl Ketones with Acyclic Aliphatic Ketones

摘要

Hetero-Diels-Alder (HDA) reaction of alpha,beta-unsaturated trifluoromethyl ketones with acyclic aliphatic ketones has been developed. The effect of acids, the amounts of acid, and solvents on the reaction were investigated, and the optimal condition for the reaction was obtained. In the presence of N,N'-dimethylethylenediamine (10 mol%), p-nitrobenzoic acid (20 mol%), and toluene at room temperature as the reaction system, HDA reactions of the different alpha,beta-unsaturated trifluoromethyl ketones with acyclic aliphatic ketones, afforded trifluoromethylated tetrahydropyranone derivatives in high yields (up to 86%). All compounds were characterized by infrared, mass, proton nuclear magnetic resonance, and carbon-13 nuclear magnetic resonance.