Organ, Michael - University of Ottawa - Department of Chemistry and Biomolecular Sciences

研究领域

Research in the area of catalysis follows two related tracks in our group: 1) mechanistic study and 2) applying catalysis to solve synthetic challenges that otherwise are difficult, if not impossible. 1) Mechanistic studies in catalysis: While most catalytic reactions have mechanisms drawn out in textbooks, we learn new things about most reactions every day – one thing is for sure, no reaction is a simply as it may seem on the surface. Our group has been interested in the role of additives and how they impact catalytic reactions. In short, while not a starting material in the Negishi reaction, salt additives play a pivotal role that went unnoticed and/or poorly understood for decades. For arylzinc cross-coupling partners, we have proposed that simply table salt is necessary to both adjust the polarity of the cross-coupling solution to breakdown aggregates to make the organozinc more likely to undergo transmetallation. With alkylzincs, we propose (in blue in Scheme 1) that a different role for the salt exists leading to the formation of a more nucleophilic zincate (RZnX3)-2 and that that is the transmallating species and not the simple organometallic (in red) or the lower zincate (RZnX2)-1 as has been proposed by others.1 Scheme 1. Our proposed mechanism of the Negishi Reaction We look at the mechanism of a number of cross coupling reactions (e.g., Suzuki Miyaura, Negishi, and cross coupling with nitrogen and sulfur nucleophiles) using a breadth of tools including kinetics, mass spectrometry, NMR spectroscopy, and calculations (in collaboration). 2) Solving old problems with new catalysts: The importance of cross-coupling to organic synthesis cannot be overstated as evidenced by the awarding of the 2010 Nobel Prize to Negishi, Suzuki, and Heck. Earlier studies focused primarily on the coupling to two different aryl rings together – itself a major feat at the time and still the best and most general strategy to assemble to aromatic rings together. In addition to the formation of C-C bonds, cross-coupling can now be used essentially to make any linkage (e.g., C-N, C-O, C-S). Once it became clear that transition metals could be used to assemble electrophiles and nucleophiles, the bar has been raised to try to do such couplings with selectivity. For example, primary amines (Scheme 2a)2 or ammonia (Scheme 2b)3 can couple to one aryl electrophile, or it can over couple to generate the diaryl product. Scheme 2. Selective (hetero)arylation of a) primary amines and b) ammonia Our group has also been highly active in the cross coupling of secondary nucleophiles to (hetero)arylhalides to produce tertiary centres adjacent to the ring without any migratory insertion that leads to the productions of isomers (Scheme 3).4 Scheme 3. Selective coupling of secondary alkylzinc nucleophiles to (hetero)aryl halides. We collaborate with a large number of companies and our students and post-docs have spent time in the labs of the industrial partner.

近期论文

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141. Chen, X.; Organ, M. G.; Pietro, W. Langmuir, 2016. A Facile Controlled Preparation Method of Multifunctional Core-Shell Magnetic Nanoparticles by Thiol-ene Click Reactions, and Their Potential Use in Microfluidic Separations. 140. Kwak, J. S., Tsoy, D., Mallik, D., Organ M. G. Org. Proc. Dev. Res. 2016, 20, A Multi-Position Valve for Uninterrupted Sampling from Heterogeneous Slurries - An Application for Flow Chemistry. 139. Lombardi, C.; Day, J.; Chandrasoma, N.; Mitchell, D.; Rodriguez, M. J.; Farmer, J. L.; Organ, M. G. Organometallics 2016. The Selective Cross-coupling of (Hetero)aryl Halides with Ammonia to Produce Primary Arylamines using Pd-NHC Complexes. 138. Khadra, A.; Organ, M. G. J. Flow. Chem. 2016, 5. Generation and Use of Benzyne Intermediates for Diels-Alder Cycloaddition in Flow. 137. Teci, M.; Tilley, M.; McGuire, M. A.; Organ, M. G. Org. Proc. Dev. Res. 2016, 20, 1967-1973. Handling hazards using continuous flow chemistry: synthesis of N1-aryl-1,2,3-triazoles from anilines via telescoped three step diazotization / azidodediazotization / [3 + 2] dipolar cycloaddition processes. 136. Teci, M.; Tilley, M.; McGuire, M. A.; Organ, M. G. Chem. Eur. J. 2016, 22, 17405-17407. Using anilines as masked cross-coupling partners: design of a telescoped three-step flow diazotization, iododediazotization, cross-coupling process. 135. Sharif, S.; Mitchell, D.; Rodriguez, M. J.; Farmer, J. L.; Organ, M. G. Chem. Eur. J. 2016, 22. N-Heteroarylation of Optically Pure α-Amino Esters using the Pd-PEPPSI-IPentCl-o-picoline Pre-catalyst. 134. Lombardi, C.; Organ, M. G. Encyclopedia of Reagents for Organic Synthesis (EROS) 2016. trans-[1,3-B(2,6-Di-3-pentylphenyl)imidazol-2-ylidene](3-chloropyridyl)palladium(II) Dichloride (Pd-PEPPSITM-IPent) 133. Atwater, B.; Chandrasoma, N.; Mitchell, D.; Rodriguez, M. J.; Organ, M. G. Chem. Eur. J. 2016, 22, Pd-PEPPSI-IHeptCl: A General Purpose, Highly Reactive Catalyst for the Selective Coupling of Secondary Alkyl Organozincs 132. Day, C.; Saledega, A.; Organ, M. G.; Wilson, D. J. Org. Proc. Dev. Res. 2016, 20. A Continuous High Efficiency Extraction Device (HEED) for Flow Synthesis. 131. Price, G. A.; Bogdan, A. R.; Aguirre, A. L.; Iwai, T.; Djuric, S. W.; Organ, M. G. Catalysis Science & Technology 2016, 6, 4733–4742. Continuous flow Negishi cross-couplings employing silica-supported Pd-PEPPSI-IPr Precatalyst. 130. Chen, X.; Organ, M. G.; Pietro, W. J. J. Nanosci, Adv. Technol. 2016, 1, 25-31. One-pot synthesis of size controllable amine-functionalized core-shell magnetic nanoparticles for use in microfluidic flow separators. 129. Schruder, C. W.; Organ, M. G.; Pietro, W. J. Current Nanoscience 2016, 12, 448-454. Metal nanoparticle impregnated controlled-size silica macrospheres as a microwave-transparent catalyst system for MACOS. 128. Tilley, M.; Li, G.; Savel, P.; Mallik, D.; Organ, M. G. Org. Proc. Dev. Res. 2016, 20, 517-524. An Intelligent Continuous Collection Device for High-Pressure Flow Synthesis:Design and Implementation. 127. Sharif, S.; Rucker; R. P.; Chandrasoma, N.; Mitchell, D.; Rodriguez, M. J.; Pompeo, M.; Froese, R. D. J.; Organ, M. G. Angew. Chem. Int. Ed. 2015, 54, 9507-9511. (Angew. Chem. 2015, 127, 9643–9647). Selective Monoarylation of Primary Amines using the Pd-PEPPSI-IPentCl Precatalyst. 126. Atwater, B.; Chandrasoma, N.; Mitchell, D.; Rodriguez, M. J.; Pompeo, M.; Froese, R. D. J.; Organ, M. G. Angew. Chem. Int. Ed. 2015, 54, 9502 –9506. (Angew. Chem. 2015, 127, 9638–9642). The Selective Cross-Coupling of Secondary Alkyl Zinc Reagents to Five-Membered-Ring Heterocycles Using Pd-PEPPSI-IHeptCl. 125. Farmer, J. L.; Froese, R. D. J.; Lee-Ruff, E.; Organ, M. G. Chem. Eur. J. 2014, 20, 1888-1893. Solvent Choice and Kinetic Isotope Effects (KIE) Dramatically Alter Regioselectivity in the Directed Ortho Metallation (DoM) of 1,5-Dichloro-2,4-dimethoxybenzene. 124. Somerville, K.; Tilly, M.; Li, G.; Mallik, D.; Organ, M. G. Org. Proc. Dev. Res. 2014, 18, 1315-1320. A High Temperature, High Pressure Flow Reactor with Inline Analytics: Design and Implementation. 123. Sauks, J. M.; Mallik, D.; Lawryshyn, Y.; Bender, T.; Organ, M. G. Org. Proc. Dev. Res. 2014, 18, 1310–1314. A Continuous Flow Microwave Reactor for Conducting High Temperature and High Pressure Chemical Reactions. 122. Farmer, J. L.; Pompeo, M.; Lough, A. J.; Organ, M. G. Chem. Eur. J. 2014, 20, 15790-15798. (IPent)PdCl2(morpholine): A Readily Activated Pre-Catalyst for Room Temperature, Additive-Free Carbon-Sulfur Coupling. 121. Oderinde, W. S.; Froese, R. D. J.; Organ, M. G. Chem. Eur. J. 2014, 20, 8579-8583. On the Hydrostannylation of Aryl Propargylic Alcohols and Their Derivatives. Remarkable Changes in Both Regio- and Stereoselectivity When Radical- vs. Non-Radical Mediated. Highlighted SYNFACT 2014, 10(10), 1073. 120. McCann, L. A.; Organ, M. G. Angew. Chem. Int. Ed. 2014, 53, 4386-4389. (Angew. Chem. 2014, 126, 4475-4478). On The Remarkably Different Role of Salt in the Cross-Coupling of Arylzincs From That Seen With Alkylzincs. “News of the Week” in Chemical and Engineering News, April 7, 2014 issue 14, p 7. Highlighted SYNFACT 2014, 10(7), 0736.