Reduction of .DELTA.24 of lanosterol in the biosynthesis of cholesterol by rat liver enzymes. II. Stereochemistry of addition of the C-25 proton

Synthesis and C-25 chirality of 26-hydroxycholesterols

“…A Hilger MK-III instrument was used for the measurement of all optical rotations. 4 The optical rotations of the samples of cholest-4-en-3on-26-ols were also recorded on a Rudoph and Son's photoelectric polarimeter.4 The CD measurements were carried out on a Jasco J-40 instrument. Chromatography, Gas chromatographic (GLC) analyses were performed on a Perkin-Elmer Model 811 instrument equipped with a flame ionization detector.…”

“…23% Optical Purity) (Hydroboration of 4 with Disiamylborane). The preparation of 4 and its selective hydroboration with disiamylborane to yield 6a was carried out exactly as previously described.68 The obtained 3-THP ether 6a was then hydrolyzed to the 3,26-diol 6b, mp 168.5°, [a]25D -35.9 ± 1.53°( c 1.31, CHClg). 25S, ca.…”

“…The 26-p -bromobenzoates 3b (derived from kyptogenin), 7b (derived from hydroboration of 26 with (+) -diisopinocampheylborane), 8b (derived from hydroboration of 25 with disiamylborane), and 8e (derived from hydroboration of 25 with (-)-diisopinocampheylborane) were prepared as previously described. 4,16 Preparation of Cholest-4-en-3¡9,26-diol 26-p-Bromobenzoates. (25S)-Cholest-4-en-3-on-26-ol p-bromobenzoate (8g, ca.…”

Microbiological Oxidation of Steroid Hydrocarbons

“…A third and potentially more promising pathway of sterol catabolism in some bacteria is side-chain oxidative degradation. Oxidation of a terminal methyl group of cholesterol has been reported using MJvobacrerium (Zaretskaya er al., 1968;Schubert et al, 1969;Galli-Keinle et al, 1973) and Nocardia species (Sih et al, 1968a). Subsequent side-chain breakdown appears to proceed via /I-oxidation or a similar process to give C2,, C,, and C,, carboxylic acids such as compound 1 (Fig.…”