Catalytic stereoselective cascade reactions of quinols with trifluoromethyl ketones: direct access to CF₃-containing 1,3-dioxolanes

A general and efficient synthesis of CF₃-containing 1,3-dioxolanes using Et₃N-catalyzed ketalization/oxa-Michael cascade of quinols with trifluoromethyl ketones is described. The reaction works efficiently under mild reaction conditions and produces the desired products in 68%–95% yields with acceptable diastereoselectivities. In addition, the reaction proceeds smoothly to give the desired product 3a in 92% yield and with high ee (80%) in the presence of a chiral catalyst (DHQ)₂PHAL.