Highly Enantioselective Synthesis of α ‐Trifluoromethyldihydropyrans Using a Chiral Trifluoroethyl‐substituted Thiourea Catalyst Derived from Amino Acid

An enantioselective Michael addition of ethyl 4,4,4‐trifluoro‐3‐oxobutanoate to α , β ‐unsaturated ketone esters using a chiral alkyl‐substituted thiourea catalyst is reported. Excellent levels of stereo‐induction (up to 98% ee ) under mild reaction conditions were obtained to afford the corresponding α ‐trifluoromethyldihydropyrans.