Asymmetric synthesis using reactions with modest group selectivity

The isomeric purity of products from certain group-selective reactions can be significantly amplified when reactions can occur sequentially. The theoretical basis for a strategy that exploits reactions with modest enantiotopic group selectivity for asymmetric synthesis is described. The relationships between conversion, yield, and isomeric purity for such a process are calculated using a simple kinetic model. A simple method for selecting candidate group-selective reactions from known face-selective reactions is presented. Application of the strategy is illustrated with the reduction of D -glucose and D -galactose derived dialdehydes with B-isopinocampheyl-9-borabicyclo[3.3.1]nonane (Alpine-Borane®).