Steroids. Part VI. Acid-catalysed Wittig reaction
Abstract
The Witting reaction between resonance-stabilised phosphoranes and steroid ketones under acid catalysis has been studied. Only ethoxycarbonylmethylene- and cyanomethylene-triphenylphosphorane and 3-oxo-steroids having no α-substituents can be successfully employed in this reaction. The stereochemistry of the olefin produced is the same as in the corresponding Wittig reaction conducted under basic conditions.