Preparation of 2R, 3S, 2'R-nadolol enantiomer using S-(-)-menthyl chloroformate as a chiral derivatizing reagent.

Stereoisomers of nadolol were derivatized with S-(-)-menthyl chloroformate((-)-MCF) forming their diastereomers, RSR-nadolol-(-)-MCF, SRS-nadolol-(-)-MCF, RRS-nadolol-(-)-MCF and SSRnadolol-(-)-MCF. Diastereomeric mixture were then chromatographically resolved by preparative HPLC (JAIGEL-ODS-BP-L, 500 × 25 mm column) eluted with methanol-water (84:16, v/v) at flow rate 2.5 mL/min. RSR-nadolol-(-)-MCF diastereomer was hydrolyzed with 5% LiOH at 80°C for 48 h, and the decomposed mixture was further purified by semi-preparative HPLC. The purity and final yield of RSR-nadolol were 99.97% and 12.95%, respectively.