Highly Enantioselective Intermolecular Alkylation of Aldehydes with Alcohols by Cooperative Catalysis of Diarylprolinol Silyl Ether with Brønsted Acid

Two cooperative systems: I/2,3,4-trihydroxybenzoic acid and I/TfOH effect highly enantioselective intermolecular α-alkylation of aldehydes. These systems afford functionalized aldehydes in high yields, and with excellent ee and de values with broad substrate scope (see scheme; R1=alkyl, R2,R3=aryl, or R2=ferrocenyl, R3=phenyl, or R2=indolyl, R3=phenyl).