Preparation and purification of L-(+/-)-5-formyl-5,6,7,8-tetrahydrofolic acid

Reinvestigation of the conversion of folic acid to leucovorin [L-(+/-)-5-CHO-THF] led to improved methods for the synthesis of this drug, which is suitable for clinical use. Also, methods were developed for the chromatographic and nonchromatographic purification of less pure samples of L-(+/-)-5-CHO-THF.