Collect. Czech. Chem. Commun. 1981, 46, 607-625

4,4-Dimethyl-A-homocholestane derivatives

Helena Velgová and Jorga Smolíková

Institute of Organic Chemistry and Biochemistry, Czechoslovak Academy of Sciences, 166 10 Prague 6


The synthesis of epimeric bromo ketones VII, VIII, XXV and XXVI, derived from 4,4-dimethyl-A-homo-4a-cholesten-3-one (I) and 4,4-dimethyl-A-homo-5-cholesten-3-one (XIII) is described in this paper. In the case of bromo ketones VII, VIII and XXV the IR data demonstrate the presence of conformers both with a quasi-axial and a quasi-equatorial bromine atom in the equilibrium mixture, the quasi-equatorial conformer being the predominant component. On the basis of IR, CD and 1H-NMR data the conformation of the ring A in compounds VII, VIII, XXV and XXVI is discussed.