Citric Acid → Obeticholic Acid

Participants

Reaction Conditions

Reaction Steps

A mixture of compound 6 (86 g, 205.4 mmol), water (688 mL) and 50% sodium hydroxide solution (56.4 mL) was reacted with sodium borohydride (7.77 g, 205.4 mmol) in a mixture of 50% wt. sodium hydroxide solution (1.5 mL) and water (20 mL) at 90° C. to 105° C. The reaction mixture was heated to reflux and stirred for at least 3 hours. For the workup, after the reaction was complete, the reaction mixture was cooled to approximately 80° C. and transferred to a cooled reactor. At 30° C. to 50° C., n-butyl acetate (860 mL) and citric acid (320.2 g, anhydrous) in water (491 mL) were added. The aqueous phase was separated and discarded after checking the pH-value to make sure that it was acidic. The organic phase was transferred and distilled. The residue is diluted with n-butyl acetate and was slowly cooled to 15° C. to 20° C. and the crude obeticholic acid was filtered using a centrifuge. The wet product was crystallized from n-butyl acetate. The product obeticholic acid was isolated and washed with n-butyl acetate (43 mL, 4 times) in an inert pressure filter. Drying was done in the pressure filter under vacuum at approximately 80° C. This led to 67.34 g (77.9%) of crystalline obeticholic acid. See example 3 for full details regarding the identification and characterization of crystalline obeticholic acid.

Provenance & Evidence