7 beta-hydroxy bile alcohols: Facile synthesis and 2D H-1 NMR studies of 5 beta-cholestane-3 alpha,7 beta,12 alpha,25-tetrol

A rapid and easily performed procedure for the synthesis of 5 beta-cholestane-3 alpha, 7 beta, 12 alpha, 25-tetrol by means of an efficient homologation sequence of the intermediate, 3 alpha, 7 beta, 12 alpha-triformyloxy-24-oxo-25-diazo-25-homo-5 beta-cholane is described. The reaction sequence involved treating the intermediate, alpha-diazoketone in methanol with 3% AgNO3 or Ag2O, anhydrous Na2CO3, Na2S2O3/H2O resulting in the formation of homoursocholic acid in high yield. Esterification of the homoursocholic acid in methanol containing a catalytic amount of methanesulfonic acid under microwave irradiation conditions gave methyl homoursocholate. The subsequent treatment of methyl homoursocholate with methyl magnesium iodide provided 5 beta-cholestane-3 alpha,7 beta,12 alpha,25-tetrol in 88% yield The products and synthetic intermediates prepared in these studies were fully characterized by the results of 1D and 2D NMR, and high-resolution mass spectral studies. These studies will help in further investigation of the defect of cholic acid biosynthesis in patients with cerebrotendinous xanthomatosis (CTX) as well as other inborn errors of bile acid metabolism. (C) 1997 by Elsevier Science Inc.