Author : Zheng Huang
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (119 download)
Book Synopsis Biomimetic Aerobic Catalysis and Total Synthesis of Dibenzocyclooctadiene Lignans by : Zheng Huang
Download or read book Biomimetic Aerobic Catalysis and Total Synthesis of Dibenzocyclooctadiene Lignans written by Zheng Huang and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Aerobic oxidation is a necessary adaptation to life on earth that has given rise to many intricate enzymatic processes. Over the course of my PhD studies, I have attempted to mimic certain enzymatic mechanisms of aerobic oxidation, in order to develop new synthetic tools for the preparation of complex, organic molecules. These studies can be divided into two phases, representative of the respective enzymes under consideration. The first focused on the development of Cu-catalysts based upon the Type III, di-copper enzyme tyrosinase. Tyrosinase is an essential enzyme that is part of the melanogenic pathway. At its center are two Cu-atoms that activate molecular oxygen (O2) as a characteristic Cu2-peroxo, in order to de-aromatize L-tyrosine. Inspired by this mechanism of O2-activation and oxygen atom transfer, I developed a series of catalytic aerobic processes for the functionalization of phenols. This included the synthesis of diaryl ethers by dehydrogenative C-O bond formation, as well as a direct synthesis of polyfunctional indoles starting from commercially available derivatives of L-tyrosine.The second phase of my studies focused on aerobic oxidations catalyzed by Fe-containing enzymes in the late stages of lignan biosynthesis. Here, our focus shifted towards the substrate, and we developed conditions to explore the fates of proposed biosynthetic radicals that are implicated in the biosynthesis of lignan-derived dibenzocyclooctadiene (DBCOD) natural products. DBCODs are secondary metabolites produced by medicinal plants of Schisandra and Kadsura that display a range of health benefits. In the final stages of their biosynthesis, certain family members are believed to be oxidized by Fe-containing oxygenases that leads to dramatic structural changes following radical cyclization. Typically, radical cyclizations are much slower than the more typical hydroxylation pathway, raising interesting mechanistic questions about how these enzymes delay or divert more traditional pathways of C-H oxidation. My work in this area led to mild, photoredox mediated conditions for late-stage radical cyclizations that could be applied to a number of highly oxidized and structurally distinct family members"--
