News & Events
Ohyun Kwon, Ph.D.
Posted on March 24, 2017
Date - March 24, 2017
Department of Chemistry and Biochemistry
University of California, Los Angeles
Title: “Phosphines and Phosphinocatalysis”
Soft nucleophilic phosphinocatalysis has been known since the 1960s as a result of the pioneering work of Horner, Price, Rauhut−Currier, and Morita. In the 1990s, Trost and Lu made important discoveries, reporting isomerization, umpolung addition, and [3+2] cycloaddition. Nonetheless, it was not until the 2000s that the area of phosphinocatalysis began to flourish. My group, through careful analysis of the mechanism of the phosphinocatalysis reactions, has demonstrated over two dozen new reactions facilitated by phosphine catalysts. The results are a one-step conversion of simple acyclic starting materials into various carbo- and heterocycles. The practical values of these one-step phosphine-catalyzed annulation processes are significant since (1) they are atom economic and environmentally friendly, and (2) the heterocycles are an immense class of organic compounds with numerous practical applications. One recent, particularly significant advancement is the creation of chiral phosphines that are derived from a natural amino acid, L-hydroxyproline. Their synthetic utility in the phosphine catalyzed annulations, application in total syntheses of (+)-ibophyllidine and (–)-actinophyllic acid, and commercialization will also be discussed. The phosphinocatalysis reactions that my group has developed have produced structurally varied heterocycles of immense value for numerous practical applications. To illustrate the utility of these heterocycles, my group has been engaged in chemical genetic studies, resulting in the identification of the following bio-modulators: (1) inhibitors of the enzymes GGTase-I and Rab GGTase; (2) an anti-arrhythmic agent (named “efsevin”) to rescue zebrafish tremblor mutant; (3) an inhibitor (named “aplexone”) of cholesterol biosynthesis that is more potent than Pfizer’s Lipitor; (4) compounds inhibiting cell migration and cell invasion; (5) interferon γ-like compounds that augment innate immune responses of macrophages; (6) inhibitors of cytotoxic T cell lytic granule exocytosis; and (7) inhibitors of serine hydrolases that are specific for platelet-activating factor acetylhydrolases 1b2 and 1b3 (PAFAH1b2/3). Chemical biological studies related with these molecules will be presented during the talk. In addition, recent development in phosphine oxide catalysis research will also be introduced.