Bortezomib Impurity 32

(αS)-(1R,2R,3S,5R)-Pinanediol-1-amino-3-methylbutane-1-boronate Trifluoroacetic Acid Salt is an isomer of (αR)-(1S,2S,3R,5S)-Pinanediol-1-amino-3-methylbutane-1-boronate Hydrochloride (P458500), a bortezomib (B675700) intermediate. A boronic acid dipeptide derivative as proteasome inhibitors.