One-step eantioselective bioresolution for (S)-2-chlorophenylglycine methyl ester catalyzed by the immobilized Protease 6SD on multi-walled carbon nanotubes in a triphasic system

( S )-2-chlorophenylglycine methyl ester (( S )- 1 ) is a key chiral building block of clopidogrel, which is a widely administered antiaggregatory and antithrombotic drug. Herein, Protease 6SD was covalently immobilized on multi-walled carbon nanotubes (MWCNT), and the as-prepared immobilizate P-6SD@NH 2 -MWCNT was applied in the enantioselective resolution of ( R,S )- 1 to yield ( S )- 1 . In order to overcome the poor solubility of ( R,S )- 1 in aqueous solution, a novel triphasic reaction system constituting P-6SD@NH 2 -MWCNT, aqueous phase and methyl tert -butyl ether (MTBE) as the organic phase was constructed, which simultaneously improved the substrate solubility and the immobilizate recyclability. Under the optimized reaction conditions, P-6SD@NH 2 -MWCNT catalyzed 10 mM ( R,S )- 1 for 2 h, yielding optically pure ( S )- 1 (>99.0 % ee s ) with 70.74 % conversion of the ( R,S )- 1 . Moreover, P-6SD@NH 2 -MWCNT can be reused for 15 batches, displaying an exquisite recycling performance. It is for the first time that enantiomerically pure ( S )- 1 was successfully synthesized by protease-catalyzed one-step resolution.