The controlled reaction of Beta-alkyldiisopinocampheylboranes with aldehydes providing a convenient procedure for the enantiomeric enrichment of the boronic ester products through kinetic resolution

Beta-alkyldiisopinocampheylboranes' (Ipc2BR) reaction with aldehydes leads to a nonenzymatic asymmetric synthesis of chiral boronate esters with an enantiomeric excess of not more than 99% from the former 81% to 96%. Aldehydes that have electron-deficient carbonyl groups have a faster rate of reaction. For this reason, addition of a Lewis acid increases the electron deficiency of aldehydes and hastens the reaction rate. The addition of aldehydes eventually results in the kinetic resolution of intermediate boronic esters.