研究领域

Synthetic organic chemistry: development of novel and selective catalytic transformations/unconventional redox processes/molecular recognition of transition states/complex target synthesis.

Our group is focused on solving problems in selective catalysis. Currently, we are interested in developing small molecule catalysts capable of coordinating sequential and selective proton, electron, and H-atom transfer events within a discrete catalytic cycle. To this end, we are developing synthetic forms of a key component of the molecular machinery involved in photosynthesis to selectively remodel the connectivity of C-H bonds within molecules of interest. The immediate practical benefits of this work will be to provide chemists with tools to transform inexpensive feedstocks into valuable products containing stereocomplex C-H bonds, streamlining the synthesis of important chiral molecules. The broader aims of this work focus on using newly discovered reactions as a platform for studying fundamental mechanistic questions concerning the relationships between bond strengths, redox properties, protonation state and molecular recognition in catalysis. These studies may ultimately yield principles that will aid the development of new technologies and their associated applications in the synthesis of bioactive natural products, pharmaceuticals, and functional materials.

近期论文

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Proton-Coupled Electron Transfer in Organic Synthesis: Novel Homolytic Bond Activations and Catalytic Asymmetric Reactions with Free Radicals. Yayla, H. G.; Knowles, R. R.; Synlett. 2014, 20, 2819–2826, doi: 10.1055/s-0034-1379304 (Synpacts article) Catalytic Olefin Hydroamination with Aminium Radical Cations: A Photoredox Method for Direct C-N Bond Formation. Musacchio, A. J.; Nguyen, L. Q.; Beard, G. H.; Knowles, R. R. J. Am. Chem. Soc. 2014, 136, 12217–12220, doi: 10.1021/ja5056774 Enantioselective Photoredox Catalysis Enabled by Proton-Coupled Electron Transfer: Development of an Asymmetric Aza-Pinacol Cyclization. Rono, L. J.; Yayla, H. G.; Wang, D. Y.; Armstrong, M. F.; Knowles, R. R. J. Am. Chem. Soc. 2013, 135, 17735-17738, doi: 10.1021/ja4100595 Catalytic Ketyl-Olefin Cyclizations Enabled by Proton-Coupled Electron Transfer. Tarantino, K. T.; Liu, P.; Knowles, R. R. J. Am. Chem. Soc. 2013, 135, 10022-10025 doi: 10.1021/ja404342j Total Synthesis of Diazonamide A. Knowles, R. R.; Carpenter, J. E.; Blakey, S. B.; Kayano, A.; Mangion, I. K.; Sinz, C. J.; MacMillan D. W. C. Chemical Science 2011, 2, 308–311. Attractive Non-Covalent Interactions in Asymmetric Catalysis: Links Between Enzymes and Small-Molecule Catalysts. Knowles, R. R.; Jacobsen, E. N. Proc. Nat. Acad. Sci. USA 2010, 107, 20678–2068 Concerning the Mechanism of the FeCl3-Cataylzed a-Oxyamination of Aldehydes. Evidence for a Non-SOMO Activation Pathway. Van Humbeck, J. F.; Simonovich, S. P.; Knowles, R. R.; MacMillan D. W. C. J. Am. Chem. Soc. 2010, 132, 10012–10014. Enantioselective Thiourea-Catalyzed Cationic Polycyclizations. Knowles, R. R.; Lin, S.; Jacobsen, E. N. J. Am. Chem. Soc. 2010, 132, 5030–5032. Modelling the Effects of Confinement on the Glass Transition Temperatures and Segmental Mobility. Kranbuehl, D.; Knowles, R.; Hossain, A.; Hurt, M. Journal of Physics: Condensed Matter 2003, 15, S1019–S1029. Monte Carlo Simulations of the Effect of Confinement Geometry on the Lowering of the Glass Transition Temperature. Kranbuehl, D.; Knowles, R.; Hossain, A.; Gilchriest, A. Journal of Non-Crystalline Solids 2002, 307, 495–502.