Pharmaceutical Green Chemistry Applied to the Chemical Synthesis of Steroid Compounds

Abstract

Steroid compounds are widely distributed in nature and are challenging substrates for the synthesis of a wide variety of important biologically active molecules. These include the sex hormones, corticosteroids and mineralocorticoids hormones, bile acids, vitamin D derivatives, cardiotonic steroids, among others, that have shown great therapeutic value for a broad array of medical conditions. Due to their biological and synthetic relevance, several chemical processes for the preparation and/or functionalization of the steroid nucleus have been developed. In some of those processes, green chemistry principles have been incorporated, allowing significant advances in synthetic chemistry applied to steroid compounds. In this review, a selection of the most relevant applications of pharmaceutical green chemistry in steroid synthesis, using chemical methods will be presented. Special emphasis will be given to catalytic processes, specially involving the use of heterogeneous catalysts, microwave technologies and ionic liquids as solvents. This review is organized according to the reaction type that include oxidation and reduction reactions, protection/deprotection transformations, glycosylations, rearrangements, olefin methathesis, preparations of heterocycles using different strategies and miscellaneous reactions. Biocatalytic methods applied to steroid synthesis are out of the scope of this review. Keywords: Alternative solvents, catalysis, green technologies, pharmaceutical green chemistry, steroids.