The present invention provides a synthetic process for producing bortezomib using a novel intermediate. The present invention also provides a process for purifying bortezomib anhydride, and a new crystalline polymorph of bortezomib anhydride.
A synthetic process for producing bortezomib comprising converting racemic boronic esters, such as the pinacol α-aminoboronic ester, into mixtures of diastereomers [6] by reaction with a suitably protected L-phenylalanine derivative (see Scheme 3), such as N—BOC-L-phenylalanine. The protecting group of the L-phenylalanine moiety is then removed, such as by reacting the diastereomers [6] with an acid, such as hydrochloric acid, to form a mixture of amine salt diastereomers [7] which is then subjected to conditions under which the desired diastereomer (R,S)-[7] is selectively isolated, such as by crystallization, chromatography or stereoselective hydrolysis. The separated desired diastereomer (R,S)-[7] is then converted into bortezomib or bortezomib anhydride.
Asymmetric Copper-Catalyzed Synthesis of α-Amino Boronate Esters from <i>N</i>-<i>tert</i>-Butanesulfinyl Aldimines
作者:Melissa A. Beenen、Chihui An、Jonathan A. Ellman
DOI:10.1021/ja800829y
日期:2008.6.1
A general and efficient new method for the asymmetric synthesis of a-amino boronate esters has been developed. The key step is the Cu(I)-catalyzed addition of bis(pinacolato)diboron to N-tert-butanesulfinyl aldimines, which proceeds in good yields (52-88%) and with very high diastereoselectivities (>96:2) for a variety of aldimine substrates. This method was applied to an efficient synthesis of bortezomib, a potent a-amino boronic acid inhibitor of the proteasome that is in clinical use for the treatment of multiple myeloma and mantle cell lymphoma.