New methods and strategies for the synthesis of bioactive steroids and terpinoids

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DESCRIPTION (provided by applicant): This proposal is focused on the development of new enantioselective chiral catalyst-controlled approaches to bioactive steroids and diterpenes. Due to the importance of steroidal hormones for the regulation of vital biological processes in the human body, a significant portion of natural product-based drugs are derived from various natural or unnatural steroids. Steroid-based drugs are utilized for the treatment of inflammation, allergic reactions, heart diseases, cancer, metabolic diseases, and in important health-related areas such as contraception and fitness. The majority of steroid-based drugs are obtained by semi-synthesis using feedstock isolated from plant or animal sources. While nowadays such processes could be conducted on an industrial scale, the reliance on semi-synthetic methods significantly limits the structural diversity of the steroid-based small molecules available for biological evaluation. In contrast, fully synthetic approaches could significantly improve the availability of otherwise difficult-to-prepare stereoisomeric steroidal scaffolds with unusual substitution or oxidation patterns. The objective of the proposed research is to develop stereoselective Michael/double aldol cascade reactions and apply them to the rapid assembly of cardiac steroids and diterpenes of the isopimarane family. To achieve this objective, we propose the following specific aims: (1) to develop new stereoselective catalytic Michael/double aldol cascade reactions for the stereoselective synthesis of cardenolides and bufadienolides; (2) to develop chiral phosphoric acid (CPA)-controlled regioselective and stereoselective glycosylation of cardenolide-based polyols; (3) To develop an asymmetric approach to bioactive isopimaranes.