Hydroxy-steroids. Part 20. Distinction between 19-norergosta-5,7,9-trien-3β-ol (dihydroneoergosterol) and its 3α-epimer

Abstract

Two methods have been used for epimerising the 3-hydroxy-group of 19-norergosta-5,7,9-trien-3β-ol. Although the 3β- and 3α-alcohols show a close resemblance in many of their properties it is possible to distinguish between them by examining the ¹⁹F n.m.r. spectra of their α-methoxy-α-trifluoromethylphenylacetates and the ¹H n.m.r. spectra of their complexes with shift reagents. Purification of the alcohols is most reliably achieved by crystallising their 3,5-dinitrobenzoates. Measurement of optical rotation is the best method for the quantitative analysis of mixtures of the epimers.