Jolrmal o~~luoriize Cl!ernistr~~, 8 (1976) 2099222 0 Elsevier Sequoia S.A.. Lausanne Printed in the Netherlands Recetvcd: Decenlber 3. 1976 FLUORINATED STCROLS ____ PART II*: 26,27-POLYFLUORINATCD DESMOSTCROLS 9 . JOSEF E. tiERZ"", . I . ESk'ERAIJZAVAZQUEZ=iii, and SERGIO CRUZ 209 Departamento de Quimica, Centro de Investigaci6n y de Estudios Avanzados de1 IPrJ, Apartado Postal 14-740, Mgxico 14, D.F.,(Mgxico) and EBERHARD ZIETZ Organisch-Chemisches Institut der UniversitXt,Tanmann- strasse 2, GCIttingen (B.R.D.) SUMNARY The synthesis of polyfluorinated desmosterols by a '.iittig condensation between a steroidal triphenylpllosphonium ylid and polyfluorinated acetones is described. The mass spectra of these fluorinated steroids show significant differences from the unsubstituted parent compounds. INTRODUCTIOIi Desmosterol (cholest-5,24-diene-30-01) is known to be an intermediate in the biosynthesis of cholesterol (2) as well as in the formation of 24,25-dihydroxycholesterol and 24,25-di- hydroxycholecalciferol, which are precursors of Vitamin D 3 (3) * It has also been shown (4) that desmosterol, on incubation with an enzyme obtained from calf adrenal produces pregnenolone and 4-methyl-3-pentenoic acid, suggesting that it could be a di- i’; See ref. 1 To whom all correspondance should be directed ;'; $; f: This paper describes part of thesis presented by E.V. in partial fulfillment of the requirements for the degreee of Master of Sciences.