A convenient procedure for the synthesis of 5 beta-cholestane-3 alpha,7 alpha,12 alpha,25-tetrol via a modified homologation sequence of the intermediate 3 alpha,7 alpha,12 alpha-triformyloxy-24-oxo-25-diazo-25-homo-5 beta-cholane involving a homogeneous medium is described. This involves treating the intermediate alpha-diazoketone in methanol with a solution of silver benzoate in triethylamine. Grignard reaction of the resulting triformyloxy methyl homocholate yielded 5 beta-cholestane-3 alpha,7 alpha,12 alpha,25-tetrol. Large amounts of this bile alcohol were needed to further investigate the defect of cholic acid biosynthesis in patients with cerebrotendinous xanthomatosis (CTX).