A Chiral Benzyl Group as a Chiral Auxiliary and Protecting Group for the Synthesis of Optically Active 1,2-Diols and (+)-Frontalin

Chelation-controlled asymmetric nucleophilic addition of a Grignard reagent to chiral -benzyloxy ketones gives the corresponding alcohols with high diastereoselectivities (up to 96% de) by 1,4-asymmetric induction. A chiral benzyl group is used as a chiral auxiliary as well as a protecting group for the synthesis of optically active 1,2-diols and (+)-frontalin.