Chiral vinyl dioxazaborocines in synthesis: asymmetric cuprate additions to β-boronyl acrylates and vinyl sulfones

The first examples of the addition of organometallic reagents to electron deficient boron-substituted olefins are reported. Thus, copper catalysed addition of Grignard reagents to chiral acryloyl and vinylsulfonyl dioxazaborocines, followed by oxidative removal of the boron, gives β-hydroxy esters and sulfones with asymmetric inductions up to 81 and 95% ee, respectively.