NEW SYNTHESIS OF BIOCHEMICALS WITH HOMOGENEOUS CATALYSTS

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The ultimate goal of our research is to design and develop multi-functional multi-catalyst systems for the synthesis of biochemicals, which enable us to carry out multi-step synthesis using simple starting materials in one-pot in a highly organized manner. Those sophisticated catalyst systems may eventually replace many conventional methods for the synthesis of pharmaceutical drugs and other biologically active compounds of medicinal interest. As the continuation of our fundamental approach to this challenging goal, we will focus on the development of new and efficient methods for the catalytic asymmetric synthesis of nitrogen heterocycles, especially izidine alkaloid skeletons, promoted by chiral transition metal catalysts as well as chiral Lewis acids, in the next funding period (requesting four years). The proposed research includes the following four projects: (1) Development of new methods for the synthesis of nitrogen heterocycles through chelation-controlled carbonylations, in which we will continue our successful applications of chelation-controlled carbonylations to the synthesis of various pyrrolizidine, indolizidine, and quinolizidine alkaloid skeletons through new annulation reactions based on intramolecular hydrocarbonylations as well as diastereoselective reactions of N-acylimine/N-acyliminium ion via O-ethyl hemiamidals readily obtained by intramolecular amidocarbonylation of N-alkenylamides and alkenamides; (2) Development of novel asymmetric coupling reactions of N-acylimine and Nacyliminium ion intermediates promoted by chiral Lewis acids, in which we will explore those highly promising novel reactions, providing powerful method for asymmetric carbon-carbon bond formation; (3) Development of new and efficient catalytic asymmetric hydrocarbonylation processes, in which we will examine the efficacy of chiral Pt and Rh catalysts in the asymmetric intramolecular amidocarbonylation of N-alkenylamides and alkenamides; (4) Asymmetric synthesis of nitrogenheterocycles of biological relevance by means of chiral homogeneous catalysts, in which we will integrate all three methodologies for the asymmetric synthesis of a variety of izidine alkaloid skeletons chosen in the project 1 as well as castanospermine, a potential anti-AIDS and anti-cancer drug, and also develop alternative new methods for asymmetric induction.