合成路线1

Separation of the Enantiomer: The enantiomers are separated from the racemic carboxylic acid (IV). After activation of the carboxylic acid group as imidazolide (V), this compound reacts with L-phenylglycinol and toluene sulfonic acid in DMF forming the diastereomeric mixture of L-phenylglycinolamides. These diastereomers can be separated by fractionated crystallization using ethanol (diastereomer VI) or a mixture of diethylether and isopropanol (diastereomer VII) as solvents. The release of enantiomerically pure carboxylic acids (VIII) and (IX) takes place by cleavage of the amide bond with sulfuric acid, neutralization and recrystallization from ethanol. The (R)-(-)-enantiomer is the active leukotriene synthesis inhibitor BAY X 1005.