Copper-Catalyzed Enantiotopic-Group-Selective Allylation of gem-Diborylalkanes

We report a copper-catalyzed enatiotopic-group-selective allylation of gem-diborylalkanes with allyl bromides. The combination of copper(I) bromide and H-8-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 trans-metalation of gem-diborylalkanes with chiral copper complex occurs to generate chiral alpha-borylalkyl-copper species for the first time. Additional synthetic applications to the synthesis of various chiral building blocks are also included.

Automated summary

A copper-catalyzed enatiotopic-group-selective allylation of gem-diborylalkanes with allyl bromides was reported in this study. The combination of copper(I) bromide and H-8-BINOL derived phosphoramidite ligand proved to be the most effective catalytic system, providing various enantioenriched homoallylic boronate esters under mild conditions. Experimental and theoretical studies elucidated the reaction mechanism and revealed the enatiotopic-group-selective trans-metalation of gem-diborylalkanes with chiral copper complex.