Hydrochloric Acid → (R)-Dihydrolipoic acid

Participants

Reaction Conditions

Reaction Steps

The synthesis of a bidentate dithiol ligand was accomplished via the reduction of the coenzyme lipoic acid. The general procedure was described in I. C. Gunsalus, L. S. Barton, W. Gruber, J Am. Chem. Soc. 78:1763-1766 (1956). Sodium borohydride (1.2 g) was added in 30-50 mg portions to a stirring suspension of lipoic acid (6.0 g) in 117 mL of 0.25 M sodium bicarbonate in 0° C. water. The reaction was stirred for 45 minutes at 0° C., after which 100 mL toluene was added and the mixture was acidified to pH˜2 with hydrochloric acid. The toluene layer was collected and saved. The aqueous layer was washed three times with 15 mL toluene. The organic layers were combined, dried with anhydrous magnesium sulfate, filtered, and the solvent removed under vacuum, leaving behind the product dihydrolipoic acid as a yellow oil (yield 80%).

Provenance & Evidence