Design, Synthesis and Evaluation of Radical-Based Catalysts for the Direct Anti-M

California Institute Of Technology, Pasadena CA

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Abstract

DESCRIPTION (provided by applicant): Primary alcohols are important molecules in both the commodity and pharmaceutical chemical industries. Currently, their large-scale production involves the use of either high pressures of toxic and hazardous carbon monoxide and hydrogen gasses, or stoichiometric metal and peroxide reagents. A new method for their direct, catalytic synthesis by anti-Markovnikov hydration from readily available olefin precursors would be beneficial for the synthesis of bioactive small molecules, as well as polymers and commodity chemicals that benefit human health and quality of life. Current solutions to this problem either require multistep procedures, stoichiometric amounts of oxidant and/or reductant, or are limited in scope. A general approach to anti- Markovnikov hydration is proposed to proceed through radical addition to olefins, which provide the more highly substituted radical intermediate. A new catalytic cycle is developed where hydrogen atom transfer from a metal-hydroxo species generates the new carbon-hydrogen bond and propagates the radical reaction be regenerating the metal-oxo catalyst. This cycle involves two organometallic species of interchanging oxidation states, allowing reaction to proceed without the need for exogenous oxidants or reductants. This dual-mode catalysis will be facilitated by the design of dinuclear organometallic frameworks where the metal-oxo and the metal-hydroxo components are present in close proximity. This approach allows for hydrogen atom transfer to be accelerated by nature of it being an intramolecular process, and creates formal symmetry in the dinuclear redox transfer. Manganese oxo complexes have been identified as the ideal starting point for this investigation due to their known radical-type reactivity in both oxygen atom transfer and hydrogen atom transfer reactions. Olefin hydration catalysts developed from this proposal are anticipated to have general scope due to the typically high functional-group tolerance of radical reactions, allowing a wide range of alcohols to be synthesized from readily available olefin feedstocks.