Asymmetric Michael Addition of Cyanide to α,β‐Unsaturated Aldehydes Catalyzed by Diarylmethyl‐Substituted Diphenylprolinol Silyl Ethers: Thermodynamically Controlled Product Formation under Kinetic Enantioselective Catalysis

An enantioselective Michael/1,2‐addition reaction of cyanide to α,β‐unsaturated aldehydes catalyzed by diphenylprolinol silyl ether derivatives has been developed. While the 1,2‐addition reaction predominates at room temperature, elevating the temperature to 80°C favors a tandem 1,4‐addition (Michael)/1,2‐addition sequence, affording the corresponding adduct in good yield. This temperature‐dependent switch arises because the 1,2‐addition proceeds under kinetic control, whereas the 1,4‐addition is thermodynamically favored in the present system. A diarylmethyl‐substituted diphenylprolinol silyl ether bearing a bulky aryl group, such as 3,5‐dimethylphenyl, exhibited superior catalytic performance, providing high enantioselectivity even at elevated temperature. The resulting product, featuring both cyano and cyanohydrin moieties, serves as a versatile chiral intermediate amenable to further transformation into γ‐cyanoalcohols, β‐cyanoesters, and β‐cyanoamides.