Asymmetric Synthesis of Propranolol, Naftopidil and ( R )-Monobutyrin using a Glycerol Desymmetrization Strategy

Herein, an approach for desymmetrization of glycerol by using a readily available camphorsulfonamide as a starting material is described. The strategy for asymmetric synthesis of (R)/(S)-propranolol, (R)/(S)-naftopidil and (R)-monobutyrin with spiroketal formation by desymmetrization was employed and Mitsunobu reaction was used for epoxide and ether formation. Steglich esterification and CAN (cerium ammonium nitrate) mediated ketal deprotection, were key steps in the synthesis. Regioselective ring opening of epoxide gave desired molecule with good overall yield and optical purity.