High-field NMR studies of 3β-tetrahydropyranyloxy steroids

Szendi, Z.

doi:10.1016/s0039-128x(00)00103-3

Cited by 2 publications

(2 citation statements)

References 20 publications

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“…In contrast, the shift for the proton at C-3 for 3a -sterols is 0.5 ppm downfield compared to that for 3b-sterols (Kirk et al, 1990). In addition, the shift of the carbon atom C-3 (76.8-77.3 ppm, Table 2) is similar to that reported for 3b-tetrahydropyranyloxysterols (76 ppm; Szendi et al, 2000). The NMR data thus confirm the structures of Ia and IIIa, but they do not allow elucidation of the R/S stereochemistry of the steryl alkyl ethers.…”

Section: Synthesis Of Cholesteryl Alkyl Etherssupporting

confidence: 67%

Structural identification of steryl alkyl ethers in marine sediments

Schouten

Rampen

Geenevasen

et al. 2005

Organic Geochemistry

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Steryl alkyl ethers have been reported to occur in immature marine sediments up to Cretaceous age. Here, we report their unambiguous structural identification in Holocene sediments from the Arabian Sea, Pleistocene sediments from the southeast Atlantic and a Miocene sediment from the Monterey formation through chemical degradation experiments and synthesis. We show that the main steryl alkyl ethers in sediments from the southeast Atlantic are cholest-5-enyl 3b-(2-dodecanyl) ether and cholest-5-enyl 3b-(3-dodecanyl) ether together with their 24-methyl and 24-ethyl pseudo-homologues. Steryl alkyl ethers in sediments from the Arabian Sea are dominated by cholest-5-enyl 3b-(5-decanyl) ether and cholest-5-enyl 3b-(4-decanyl) ether together with their 24-methyl and 24-ethyl pseudo-homologues. The structures suggest that these compounds are formed by direct biosynthesis by as yet unknown marine organisms.

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Section: Synthesis Of Cholesteryl Alkyl Etherssupporting

confidence: 67%

Structural identification of steryl alkyl ethers in marine sediments

Schouten

Rampen

Geenevasen

et al. 2005

Organic Geochemistry

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“…64 Assignments for the carbon atom resonances of 7α-, 11α-, 12α-, and 17α-OTHP ether rings were made by comparison with reported 1 H/ 13 C NMR data on steroidal OTHP ethers. 71,72 A strong characteristic difference between the (R) and (S) isomers was observed for the dioxygenated C-2′ carbon atom resonance, which was found either at ca. 100−103 ppm for 7α-(R)-, 11α-(R)-, and 12α-(S)OTHP isomers or at ca.…”

Section: Journal Of Medicinal Chemistrymentioning

confidence: 99%

Synthesis of New Steroidal Inhibitors of P-Glycoprotein-Mediated Multidrug Resistance and Biological Evaluation on K562/R7 Erythroleukemia Cells

et al. 2015

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A simple route for improving the potency of progesterone as a modulator of P-gp-mediated multidrug resistance was established by esterification or etherification of hydroxylated 5α/β-pregnane-3,20-dione or 5β-cholan-3-one precursors. X-ray crystallography of representative 7α-, 11α-, and 17α-(2'R/S)-O-tetrahydropyranyl ether diastereoisomers revealed different combinations of axial-equatorial configurations of the anomeric oxygen. Substantial stimulation of accumulation and chemosensitization was observed on K562/R7 erythroleukemia cells resistant to doxorubicin, especially using 7α,11α-O-disubstituted derivatives of 5α/β-pregnane-3,20-dione, among which the 5β-H-7α-benzoyloxy-11α-(2'R)-O-tetrahydropyranyl ether 22a revealed promising properties (accumulation index 2.9, IC50 0.5 μM versus 1.2 and 10.6 μM for progesterone), slightly overcoming those of verapamil and cyclosporin A. Several 7α,12α-O-disubstituted derivatives of 5β-cholan-3-one proved even more active, especially the 7α-O-methoxymethyl-12α-benzoate 56 (accumulation index 3.8, IC50 0.2 μM). The panel of modulating effects from different O-substitutions at a same position suggests a structural influence of the substituent completing a simple protection against stimulating effects of hydroxyl groups on P-gp-mediated transport.

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High-field NMR studies of 3β-tetrahydropyranyloxy steroids

Cited by 2 publications

References 20 publications

Structural identification of steryl alkyl ethers in marine sediments

Structural identification of steryl alkyl ethers in marine sediments

Synthesis of New Steroidal Inhibitors of P-Glycoprotein-Mediated Multidrug Resistance and Biological Evaluation on K562/R7 Erythroleukemia Cells

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