An excellent new resolving agent for the diastereomeric resolution of rac-mandelic acid

Abstract Chiral mandelic acid ( S )- 1 , which is an important precursor for stereoselective transformations and a versatile intermediate for pharmaceuticals, was resolved with the Pope and Peachey method. Enantiopure 1-amino-3-phenoxypropan-2-ol ( S )- 2 , a key intermediate for pharmaceuticals, was used to resolve rac -mandelic acid rac - 1 successfully for the first time. The less soluble salt ( S )- 1 ·( S )- 2 ·H 2 O could be obtained in 77% yield and 98% de ( E 75%) using ( S )- 2 and LiOH in water. The crystal structure of the less soluble salt ( S )- 1 ·( S )- 2 ·H 2 O showed that the water molecule played a key role in forming the crystals.