Stereogenic boron in 2-amino-1,1-diphenylethanol-based boronate–imine and amine complexes

Abstract

Racemic boronate-imine and boronate-amine complexes 8 and 10, both featuring a stereogenic boron atom were synthesized from 2-amino-1,1-diphenylethanol (5) and characterized by crystal structure analyses. Proof of enantiomerism at the boron center for the novel boronate-amine complex 10 was established by separation of the enantiomers. Racemization barriers were found to be in the same range for both amine and imine complexes (100-110 kJ/mol).