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).