Compounds related to provitamin D3 (III)): Homocholesterol and the corresponding provitamin (3‐homoprovitamin D3)
- 1 January 1951
- journal article
- research article
- Published by Wiley in Recueil des Travaux Chimiques des Pays-Bas
- Vol. 70 (5) , 389-402
- https://doi.org/10.1002/recl.19510700503
Abstract
3‐Homocholesterol (III), obtained by action of LiAlH4 on cholesteryl‐3‐carboxylic methyl ester (II), which has been prepared from cholesteryl chloride by Grignard reaction, has the same steric configuration (β) at carbon atom 3 as cholesterol. Bromination of its acetate (IV) by means of bromosuccinimide, followed by elimination of HBr, leads to the acetate of 3‐homoprovitamin D3 (Vα).This 3‐homoprovitamin D3 (IX) can be synthesized with a far better yield by introducing first the double bond 7 and then the hydroxymethyl group 3. The magnesium derivative of 7‐dehydrocholesteryl chloride is transformed by CO2 into the carboxylic acid (VII), which is readily methylated with diazomethane. Finally the 7‐dehydrocholesteryl‐3‐carboxylic methyl ester (VIII) is reduced with LiAlH4 to 3‐homoprovitamin D3 (IX).It is pointed out that the ultraviolet absorption characteristic for the conjugated system of double bonds 5‐7 is subjected to an influence of molecular size.Keywords
This publication has 6 references indexed in Scilit:
- 84. Studies in light absorption. Part IX. The relation between absorption intensities and molecular dimensions, and its application to the electronic spectra of polyenes and polycyclic benzenoid hydrocarbonsJournal of the Chemical Society, 1950
- Synthèse de Stérols à Chaînes Latérales VariéesRecueil des Travaux Chimiques des Pays-Bas, 1950
- Compounds related to provitamin D3 (I). 7‐Dehydrocholesteryl chloride and bromideRecueil des Travaux Chimiques des Pays-Bas, 1950
- Derived Steroids. I. Cholesteryl Ketones1Journal of the American Chemical Society, 1948
- Studies on Sterols. V. epi-CholesterolJournal of the American Chemical Society, 1936
- Racemization in the Preparation of the Grignard ReagentJournal of the American Chemical Society, 1935