Potential bile acid metabolites: IV. Inversion of 7α‐hydroxyl; ursodeoxycholic acid

Abstract
A new method for inversion of chenodeoxycholic to ursodeoxycholic acid which does not involve an intermediary ketone is described. Methyl chenodeoxycholate‐3‐cathylate‐7‐mesylate undergoes a mild reaction with potassium superoxide‐18‐crown ether‐6 in DMSO to give ursodeoxycholic acid in good yield.