SYNTHESIS OF TRITERPENE ANTIBIOTICS FROM BILE-ACIDS .4. CATALYTIC-HYDROGENATION OF METHYL-4,4-DIMETHYL-5-CHOLENE-3-ONE-24-OATE

Catalytic hydrogenation of methyl 4,4 dimethyl chol-5 en-3-one-24 oate, prepared from lithocholic acid has been carefully studied in a variety of conditions (solvent, temperature, pressure, nature and amount of catalyst). Fairly mild conditions have been found, which lead to the 5.alpha. dihydroderivative, and do not affect the .DELTA.8(9) double bond of lanosterol. Therefore, one of the major difficulties of the conversion of bile acids into tetracyclic triterpene antibiotics has been overcome.