Practical implications of boron-to-zinc transmetalation for the catalytic asymmetric arylation of aldehydes

Transmetalation from aryl boronic acids and triaryl boroxines to diethylzinc takes place within minutes following a two-step, low-energy pathway (see picture), according to density functional calculations and reaction microcalorimetry measurements. The experimental conditions for a practical, atom-economical, and highly enantioselective catalytic arylation of a variety of aldehydes have been developed from these data.