Catalytic enantiotopic-group-selective cross-couplings of achiral geminal bis(pinacolboronates) provide a route for the construction of nonracemic chiral organoboronates. In the presence of a chiral monodentate taddol-derived phosphoramidite ligand, these reactions occur with high levels of asymmetric induction. Mechanistic experiments with chiral 10B-enriched geminal bis(boronates) suggest that the reaction occurs by a stereochemistry-determining transmetalation that occurs with inversion of configuration at carbon.

Under the influence of a chiral palladium catalyst, 1,1-bis(pinacolboronate) esters undergo asymmetric cross-coupling with bromoalkenes to generate nonracemic allyl boronates with high levels of enantioselectivity. The so-formed allyl boronates may be oxidized with hydrogen peroxide to provide secondary allylic alcohols or with nitrosobenzene to furnish nonracemic tertiary allylic alcohols. Mechanistic experiments suggest the operation of a pathway involving outer-sphere stereoinvertive transmetalation.

The catalytic Suzuki-Miyaura cross-coupling with chiral γ,γ-disubstituted allylboronates in the presence of RuPhos ligand occurs with high regioselectivity and enantiospecificity, furnishing nonracemic compounds with quaternary centers. Mechanistic experiments suggest that the reaction occurs by transmetallation with allyl migration, followed by rapid reductive elimination.

Nonracemic Allylic Boronates Through Enantiotopic-Group-Selective Cross--Coupling of Geminal Bis(boronates) and Vinyl Halides. -Under the influence of a chiral palladium catalyst, 1,1-bis(pinacolboronate) esters undergo asymmetric cross-coupling with bromoalkenes to generate nonracemic allyl boronates with high levels of enantioselectivity. Resulting allyl boronates can be used for further transformations. Mechanistic experiments suggest a pathway involving outer-sphere stereoinvertive transmetalation. -(POTTER, B.; SZYMANIAK, A. A.; EDELSTEIN, E. K.; MORKEN*, J. P.; J. Am. Chem. Soc. 136 (2014) 52, 17918-17921, http://dx.

A stereospecific Suzuki—Miyaura coupling of highly substituted allylboronates with C‐electrophiles provides a highly regiospecific and enantiospecific access to quarternary carbon centres.