PubMed · 13410374
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
F N MITCHELL, J E MITCHELL. 1957. Vitamin-D-resistant rickets.. https://doi.org/10.1001/archpedi.1957.02060040387005
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
Cholestane-3beta,5alpha,6beta-triol is an extensively studied biologically important oxysterol. The full set of eight cholestane-3,5,6-triol stereoisomers was synthesised in diastereomerically pure forms by the stereoselective cleavage of eight diastereomerically pure 4,5-epoxycholestane-3,6-diols with LiAlH4, in high yields on multigram scales and without chromatography for most of them. However, applying various reportedly successful combinations of a hydride donor and a Lewis acid to the same substrates under a variety of conditions failed to generate a single unsubstituted cholestane-3,4,6-triol. The products of the eight cholestane-3,5,6-triol stereoisomers will serve as a good probe in the study of biological functions of oxysterols in a biological process.
[reaction: see text] A facile approach for the conversion of a spirostan saponin into its furostan counterpart, as illustrated by the transformation of dioscin to methyl protodioscin (and its 26-thio-analogue), has been developed.
A crystallographic comparison of some geometrical and structural features for a series of steroids (cholestane derivatives) is made in the present paper. Selected bond distances and bond angles of interest are discussed in detail. Conformations of individual ring systems in a series of 28 cholestane derivatives are calculated and discussed. Graphical presentations of ring conformations are made for all the five- and six-membered rings to show the frequency of their occurrence. X--H...A intra- and intermolecular interactions in the identified molecules are discussed with the standard distance and angle cut-off criteria. Distance-angle scatter plots for both kinds of interactions are presented for better understanding of packing interactions existing in cholestane molecules.