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NATURAL PRODUCT INSPIRED METHODOLOGIES: ADVANCES IN DIASTEREOSELECTIVE N-SULFINYL IMINE AND TRIFLUOROPYRUVIC ACID REACTIONS

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Thesis/Dissertation
Date
2023-08
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Department
Chemistry
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DOI
http://dx.doi.org/10.34944/dspace/9474
Abstract
My research work focused on the development of methodologies to enable efficient synthesis of natural products. In the Andrade lab I developed N-sulfinyl metallodienamine (NSMD) and metalloenamine (NSME) methodologies for the asymmetric synthesis of natural products. In 2017, our first report of a novel diastereoselective hydroxylation protocol for metallodienamine (with 4:1 dr) in concise 14-step synthesis of (−)-albocycline warranted further exploration of the method. By screening different metal bases, I was able to observe a unique diastereoselective switch. DFT computational modeling assisted with experimental analysis suggested a favoritism of metallodienamine geometry by choice of metal bases as the origin of the diastereoselective switch. The method worked well with a diverse set of N-sulfinyl aldimines and ketimines with 50-99% yield and 3:1 to 98:2 diastereoselectivity. A one-pot protocol was developed to access 1,2 amino alcohols with high diastereoselectivity. With a good understanding of the diastereoselective reaction with NSMD and NSMEs, I joined with Dr. Po-Cheng Yu to develop a highly diastereoselective domino Michael/Michael/Mannich reaction for the concise total synthesis of (+)- epiibogamine. The domino reaction enabled us to set all the stereocenters in the natural product in a single step with high diastereoselectivity enabling access to the natural product in a concise 7 steps. I also worked briefly on developing diastereoselective oxidative coupling with N-sulfinyl imine for the synthesis of (+)-chimonanthine. At the beginning of my fourth year I Joined the Kim lab, where I developed photoredox catalyzed process to synthesize y-lactones. These motifs are found in various natural products and require multistep to access. I developed a method that enables quick access to these motifs in one step.
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