Abstract: A method to stereospecifically prepare a steroidal sapogenin or a derivative thereof by reducing a 3-keto,5?-H steroidal sapogenin with a hindered organoborane or an organo-aluminium hydride. A 3?-hydroxy,5?-H steroidal sapogenin or derivative thereof may be prepared by reducing the 3-keto,5?-H steroidal sapogenin using as reducing agent a relatively highly hindered organoborane reagent or by SN 2 inversion of a 3?-hydroxy,5?-H steroidal sapogenin or derivative thereof. The organo-aluminium hydride may be used to prepare a 3?,5?-H steroidal sapogenin or derivative thereof. The invention provides a convenient route to useful steroidal sapogenins such as sarsasapogenin, episarsasapogenin, smilagenin, epismilagenin and esters thereof, from readily available or easily preparable starting materials (e.g. diosgenone, preparable from diosgenin).

Abstract: A method for selectively separating desirable steroidal glycosides from undesirable components present in plant material of the Asclepiadaceae family containing the same. The method comprises contacting the plant material or material derived therefrom (herein: “the material”) with liquid or supercritical carbon dioxide under conditions whereby the desirable steroidal glycosides dissolve in the liquid or supercritical carbon dioxide in preference to the undesirable components, and subsequently recovering the desirable steroidal glycosides from the carbon dioxide solution.