Oxidation reactions exhibit significant value in the synthesis of pharmaceuticals, natural products and other bioactive compounds, since they often facilitate the introduction of heteroatoms into these molecules. The majority of methods for performing oxidation reactions rely on undesirable oxidants that generate stoichiometric waste, which often limits their use in large-scale applications (e.g., process-scale pharmaceutical synthesis). In contrast, Nature widely uses the most abundant oxidant, O2, in selective oxidation reactions. Many oxygenases and oxidases feature redox-active organic (co)catalysts, such as quinones and tyrosyl radicals, in the active site of the enzyme. In the proposed work, we will develop reactions catalyzed by three bioinspired classes of redox-active (co)catalysts for synthetic oxidation reactions: (1) quinone catalysts for oxidative dehydrogenation and oxidative coupling reactions of amines and other substrates, (2) nitroxyl radical (co)catalysts for oxidative coupling reactions, and enantio-, diastereo-, and chemoselective oxidations of alcohols, and (3) imidoxyl radical (co)catalysts for oxidative conversion of activated C?H bonds into C?N, C?O, and other C?X bonds. The quinone-catalyzed reactions will facilitate dehydrogenation and oxidative coupling reactions of N-heterocycles, which are present in >50% of small-molecule drugs. The Cu/nitroxyl chemistry will be used to achieve versatile oxidative coupling reactions to generate amides, carbamates, and ureas as well as site-selective alcohol oxidation in complex molecules, including late-stage functionalization of natural products and pharmaceuticals. The imidoxyl radical chemistry will exploit the utility of electrochemical methods to overcome intrinsic limitations identified in prior studies and will provide the basis for selective generation of carbon-based radicals that can undergo subsequent functionalization. In each of these project areas, empirical reaction discovery efforts will be complemented by holistic mechanistic studies of the catalytic mechanisms and redox behavior of the (co)catalysts.

Public Health Relevance

Selective oxidation of organic molecules represents one of the key reaction classes used the discovery and manufacture of pharmaceutical intermediates and therapeutic agents. The research outlined in this proposal takes inspiration for enzymatic transformations to develop new selective oxidation methods.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
3R01GM100143-07S1
Application #
9699659
Study Section
Program Officer
Lees, Robert G
Project Start
2012-04-01
Project End
2020-03-31
Budget Start
2018-04-01
Budget End
2019-03-31
Support Year
7
Fiscal Year
2018
Total Cost
Indirect Cost
Name
University of Wisconsin Madison
Department
Chemistry
Type
Schools of Arts and Sciences
DUNS #
161202122
City
Madison
State
WI
Country
United States
Zip Code
53715
Wang, Fei; Rafiee, Mohammad; Stahl, Shannon S (2018) Electrochemical Functional-Group-Tolerant Shono-type Oxidation of Cyclic Carbamates Enabled by Aminoxyl Mediators. Angew Chem Int Ed Engl 57:6686-6690
Rafiee, Mohammad; Wang, Fei; Hruszkewycz, Damian P et al. (2018) N-Hydroxyphthalimide-Mediated Electrochemical Iodination of Methylarenes and Comparison to Electron-Transfer-Initiated C-H Functionalization. J Am Chem Soc 140:22-25
Lennox, Alastair J J; Goes, Shannon L; Webster, Matthew P et al. (2018) Electrochemical Aminoxyl-Mediated ?-Cyanation of Secondary Piperidines for Pharmaceutical Building Block Diversification. J Am Chem Soc 140:11227-11231
Nutting, Jordan E; Rafiee, Mohammad; Stahl, Shannon S (2018) Tetramethylpiperidine N-Oxyl (TEMPO), Phthalimide N-Oxyl (PINO), and Related N-Oxyl Species: Electrochemical Properties and Their Use in Electrocatalytic Reactions. Chem Rev 118:4834-4885
Jaworski, Jonathan N; McCann, Scott D; Guzei, Ilia A et al. (2017) Detection of Palladium(I) in Aerobic Oxidation Catalysis. Angew Chem Int Ed Engl 56:3605-3610
Miles, Kelsey C; Abrams, M Leigh; Landis, Clark R et al. (2016) KetoABNO/NOx Cocatalytic Aerobic Oxidation of Aldehydes to Carboxylic Acids and Access to ?-Chiral Carboxylic Acids via Sequential Asymmetric Hydroformylation/Oxidation. Org Lett 18:3590-3
Zultanski, Susan L; Zhao, Jingyi; Stahl, Shannon S (2016) Practical Synthesis of Amides via Copper/ABNO-Catalyzed Aerobic Oxidative Coupling of Alcohols and Amines. J Am Chem Soc 138:6416-9
Huynh, Mioy T; Anson, Colin W; Cavell, Andrew C et al. (2016) Quinone 1 e- and 2 e-/2 H+ Reduction Potentials: Identification and Analysis of Deviations from Systematic Scaling Relationships. J Am Chem Soc 138:15903-15910
Iosub, Andrei V; Stahl, Shannon S (2016) Palladium-Catalyzed Aerobic Dehydrogenation of Cyclic Hydrocarbons for the Synthesis of Substituted Aromatics and Other Unsaturated Products. ACS Catal 6:8201-8213
Wendlandt, Alison E; Stahl, Shannon S (2015) Quinone-Catalyzed Selective Oxidation of Organic Molecules. Angew Chem Int Ed Engl 54:14638-58

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