Figure 3. Effect of olefin concentration on e.e. and S_N2’ selectivity.

Lower alkene concentration and higher electrophile concentration can improve e.e. a, Changing the concentration of aryl olefin and/or allylic phosphate can impact e.e. With electron-neutral olefins the concentration of the allylic electrophile is mildly influential. However, with electron-deficient alkenes it is the olefin concentration that plays a major role. b, Higher chiral bis-phosphine loading leads to significant increase in e.e. See the Supplementary Information, Section 5, for experimental and analytical details. pin, pinacolato. c, Studies with D-labeled allylphosphate show that a phosphine ligand is needed for high S_N2’selectivity and that selectivity is reduced when there is excess aryl olefin, implying competitive reaction by an achiral Cu–B(pin) species.