Steroids bearing ketone functionality at carbon-7 are found commonly in nature, and the most prevalent of these are the 7-keto-delta5-sterols. These substances have diverse biological properties and are present in biological samples and food products. For the purpose of studying this class of oxysterols, many chemical methods, involving the chemical oxidation of delta5-sterols to the corresponding 7-keto-delta5-sterol derivatives have been developed to produce these compounds. We have undertaken a review and evaluation of chemical methods for the synthesis of these compounds and have endeavored to enhance one of these procedures to yield products for chemical and biological investigations.

This article reviews the utility of dioxiranes in the oxidation of 3beta-substituted delta5-sterols. Dioxiranes are the smallest cyclic peroxides that contain a carbon atom. They can be generated in situ from Oxone (2KHSO5.KHSO4.K2SO4) and a ketone. Dioxiranes are versatile oxidizing agents. The most common reaction of dioxiranes is epoxidation, with nearly 1:1 ratios of alpha/beta isomer products in all cases. delta5-Steroids with different side chains were epoxidized by dioxiranes generated in situ from several commercially available ketones. Although ketones function as catalyst, they were used in about an equivalent amount or large excess to accelerate the reaction.

Steroidal dienones represent a significant class of compounds that are useful intermediates in the further functionalization of the steroid nucleus. Their chemical synthesis can be problematic owing to the lack of a simplified method of preparation and the occurrence of impurities that can be difficult to remove. We have endeavored to develop new methods of chemical synthesis of cholest-4,6-dien-3-one that would yield a product of high purity.

For Abstract see ChemInform Abstract in Full Text.

For Abstract see ChemInform Abstract in Full Text.