CAREER: Aerobic Hypervalent Iodine Chemistry as a Platform for Oxidase Catalysis
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abstract
Oxygen (O2) is a major component of air and an ideal raw material to make chemicals. It is widely available (a component of the air we breathe), strongly oxidizing, and produces non-toxic byproducts (e.g., water). Fundamental challenges prevent widespread use of O2 in synthetic chemistry. New strategies that enable greater utilization of O2 are critical to developing sustainable synthetic methods. In this project, Dr. Powers is developing synthetic methods to use O2 to generate hypervalent iodine compounds, a class of useful chemical oxidants. The successful preparation of hypervalent iodine compounds from O2 helps achieve the goal of greater O2 utilization. The idea is that O2, which normally does not react with iodobenzene to make these hypervalent iodine reagents but does so in the presence of sacrificial aldehydes and a cobalt halide catalyst. Three research areas are proposed: improve understanding of the ensuing organic applications, innovate on routes and structures to the reagents, and couple the use of the iodine reagents with diverse dirhodium catalysts, as well as metal organic frameworks and nanoparticles, to effect C-H activations. These reactions are important to the chemical industry - ranging from the advanced manufacturing of new pharmaceuticals to other chemicals of commercial importance. Dr. Powers is also creating new programs to expand participation in science, technology, engineering, and mathematics (STEM) disciplines. For example, open-access educational resources for community college curricula are being developed. In addition, STEM education outreach programs to Historically Black Colleges and Universities (HBCUs) in Texas and are being formed to increase STEM participation by traditionally underrepresented groups.With funding from the Chemical Catalysis Program of the Chemistry Division, Dr. Powers of Texas A&M University is developing new methods to sustainably generate hypervalent iodine reagents for use in oxidation catalysis. Hypervalent iodine reagents are a class of selective two-electron oxidants that have been demonstrated to participate is a wide variety of substrate functionalization reactions including carbonyl oxidation, olefin 1,2-difunctionalization, oxidative dearomatization, alcohol and amine oxidation, as well as group-transfer chemistry. By diverting reactive intermediates generated during aldehyde autoxidation chemistry, O2 reduction can be directly coupled to the synthesis of hypervalent iodine compounds. Application of those aerobically generated intermediates in catalysis enables the broad substrate functionalization of hypervalent iodine reagents to be coupled to O2 reduction. These reactions are applicable to advanced chemical manufacturing techniques as they are more potential more sustainable and less expensive than current techniques used in pharmaceuticals and commercial chemical manufacturing. Dr. Powers is actively engaged in developing new programs that contribute to expanded participation in science, technology, engineering, and mathematics (STEM) disciplines. These activities, which involve developing new open-access educational resources for community college curricula and developing STEM education outreach programs to Historically Black Colleges and Universities (HBCUs) in Texas are directed at increasing participation in STEM education by traditionally underrepresented groups.This award reflects NSF''s statutory mission and has been deemed worthy of support through evaluation using the Foundation''s intellectual merit and broader impacts review criteria.
