SILOXANE COUPLINGS AND NATURAL PRODUCT SYNTHESIS

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DESCRIPTION: (Applicant's Abstract) The long term goal of this research is to determine the scope and limitations of the palladium-catalyzed cross-coupling of hypervalent siloxanes with allylic ester and aryl derivatives. This methodology could serve as an alternative to Stille and Suzuki coupling protocols that have several limitations in the field of natural product synthesis. In this study, the reactions of aryl, vinyl, and allyl siloxanes with a variety of substrates will be investigated. In addition, evaluation of new palladium catalysts for cross-couplings with aryl chlorides and the use of chiral ligands for an asymmetric version of the cross-coupling reaction will be undertaken. Once the scope of the coupling methodology has been determined, the siloxane methodology will be employed for the total synthesis of the antitumor antibiotic (+)-pancratastatin and the antimitotic agent (-)-colchicine.