Enantio- and Diastereoselective Synthesis of Hydroxy Bis(boronates) via Cu-Catalyzed Tandem Borylation/1,2-Addition

Catalytic enantioselective synthesis of 1-hydroxy-2,3-bisboronate esters through multicomponent borylation/1,2-addition is reported. Catalyst and substrates are readily available, form both a C–B and C–C bond, and generate up to three contiguous stereocenters. The reaction is tolerant of aryl, vinyl, and alkyl aldehydes and ketones in up to 95% yield, >20:1 dr, and 99:1 er. Intramolecular additions to aldehydes and ketones result in stereodivergent processes. The hydroxy bis­(boronate) ester products are amenable to site-selective chemical elaboration.