The rearrangement of 20-substituted bisnorallocholanes and derivatives

The cephalostatins. 21. Synthesis of bis-steroidal pyrazine rhamnosides (1)

The synthesis of bis-steroidal pyrazines derived from 3-oxo-11,21-dihydroxypregna-4,17(20)-diene (4) and glycosylation of a D-ring side chain with α-L-rhamnose have been summarized. Rearrangement of steroidal pyrazine 10 to 14 was found to occur with boron triflouride etherate. Glycosylation of pyrazine 10 using 2,3,4-tri-O-acetyl-α-L-rhamnose iodide led to 1,2-orthoester-α-L-rhamnose pyrazine 17b. By use of a persilylated α-L-rhamnose iodide as donor, formation of the orthoester was avoided. Bis-steroidal pyrazine 10 and rhamnosides 17b and 21c were found to significantly inhibit cancer cell growth in a murine and human cancer cell line panel. Pyrazine 9 inhibited growth of the nosocomial pathogen Enterococcus faecalis.

Steroid-hindered 17 beta-tertiary alcohol: characterization of dehydrated compounds

Five dehydrated compounds obtained from a tert-butyldimethylsilylchloride/imidazole or an aqueous hydrochloric acid treatment of 17 alpha-butyl-3-O-methyl estradiol in refluxing solvent were purified and characterized. Three compounds were obtained from a direct vicinal proton elimination, the two others from a vicinal elimination after migration of methyl-18. Depending on the treatment, the proportions of dehydrated compounds are different. In addition, a general profile of experimental conditions providing a similar mixture of dehydrated compounds was also established for this steroid-hindered 17 beta-tertiary alcohol.

Novel perfluoroacyl derivatives of corticosteroids and related substances for potential use in quantitative gas chromatography mass spectrometry

We investigated the potential of perfluoroacylation for gas chromatographic mass spectrometric determination of corticosteroids and related substances. Structure elucidation of the reaction products was performed with high and low resolution mass spectrometry and with proton and carbon nuclear magnetic resonance spectrometry. Besides the well known 3-enol ester formation, 17β-methyl-18-nor-13(14)-ene steroids were formed via loss of the 17-α hydroxyl group followed by a Wagner-Meerwein rearrangement. Compounds that bear an 11β-hydroxy group formed additionally a 9(11) double bond when acetone was used as solvent, whereas acetonitrile or cyclohexane led to formation of 11β-perfluoroacyl esters. In particular, perfluoroacylation of cortisol led to a clearly defined product instead of complex mixtures observed before, which thus makes it a valuable alternative to methoxime formation-silylation of cortisol for quantitative gas chromatographic mass spectrometric analyses.