Inhibitors of sterol synthesis. Synthesis and spectral properties of 3β-hydroxy-5α-cholestan-15-one and its 14β-epimer and their effects on 3-hydroxy-3-methylglutaryl coenzyme A reductase activity
3β-Hydroxy-5α-cholestan-15-one ( 2a) and its 14β-epimer 2b were prepared from 3β-acetoxy-5α-cholest-8(14)-ene ( 3). Hydroboration of 3 at 45–50°C gave a mixture of 5α, 14α-cholestane-3β, 15α-diol and 5α, 14β-cholestane-3β, 15β-diol, which were separated on silica gel as their 3β- tert-butyldimethyls...
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Published in | Chemistry and physics of lipids Vol. 74; no. 1; pp. 1 - 15 |
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Main Authors | , , , , , |
Format | Journal Article |
Language | English |
Published |
Elsevier Ireland Ltd
20.10.1994
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Subjects | |
Online Access | Get full text |
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Summary: | 3β-Hydroxy-5α-cholestan-15-one (
2a) and its 14β-epimer
2b were prepared from 3β-acetoxy-5α-cholest-8(14)-ene (
3). Hydroboration of 3 at 45–50°C gave a mixture of 5α, 14α-cholestane-3β, 15α-diol and 5α, 14β-cholestane-3β, 15β-diol, which were separated on silica gel as their 3β-
tert-butyldimethylsilyl ethers
5a and
5b. Oxidation of
5a with pyridinium chlorochromate, followed by desilylation with tetrabutylammonium fluoride gave
2a. Analogous transformations of
5b gave
2b contaminated with
2a. Desilylation of
5b followed by oxidation with pyridinium chlorochromate resulted in a mixture composed mainly of 5α, 14β-cholestane-3, 15-dione and
2b. Successive chromatographic separations on silica gel and reversed phase media gave
2b of high purity. Compound
2a was also prepared by lithium-ammonia reduction of 3β-hydroxy-5α-cholest-8(14)-en-15-one (96% yield) and by selective reduction of 5α-cholestane-3, 15-dione with lithium tri-
tert-butoxyaluminum hydride (90% yield). Isomers
2a and
2b were readily epimerized under acidic or basic conditions or under conditions used for gas chromatographic analysis. The purities of
2a and
2b were measured from nuclear magnetic resonance (NMR) spectra; chromatographic methods gave less reliable estimates of purity. NMR data also showed that ring C of the 14β sterols is predominantly in a chair conformation. The effects of
2a and
2b on the levels of 3-hydroxy-3-methylglutaryl coenzyme A reductase have been studied in Chinese hamster ovary cells. |
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ISSN: | 0009-3084 1873-2941 |
DOI: | 10.1016/0009-3084(94)90106-6 |