Copper-Catalyzed Enantiotopic-Group-Selective Allylation of gem-Diboryl alkanes

Minjae Kim, Bohyun Park, Minkyeong Shin, Suyeon Kim, Junghoon Kim, Mu-Hyun Baik* and Seung Hwan Cho* 

 We report a copper-catalyzed enatiotopic-group-selective allylation of gem-diborylalkanes with allyl bromides. The combination of copper(I) bromide and H8–BINOL derived phosphoramidite ligand proved to be the most effective catalytic system to provide various enantioenriched homoallylic boronate esters, containing a boron-substituted stereogenic center that is solely derived from gem-diborylalkanes, in good yields with high enantiomeric ratios under mild conditions. Experimental and theoretical studies have been conducted to elucidate the reaction mechanism, revealing how the enatiotopic-group-selective transmetalation of gem-diborylalkanes with chiral copper complex occurs to generate chiral α-borylalkyl-copper species for the first time. Additional synthetic applications to the synthesis of various chiral building blocks are also included.   https://pubs.acs.org/doi/10.1021/jacs.0c11750