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Pinjing Zhao

Inorganic and Organic Chemistry; Synthesis and Mechanistic Organometallic Chemistry; Homogeneous Catalysis

Rsearch Description

Research in the Zhao group focuses on the rational development of transition metal-based catalytic methods for chemical synthesis. A long-standing goal is to explore transition metal-mediated activation of strong chemical bonds such as carbon-hydrogen, carbon-carbon, and carbon-heteroatom bonds to form reactive organometallic species in homogeneous catalysis. “Classic” organometallic chemistry often generates catalytically active intermediates by oxidative addition of organic halides or by transmetalation with main-group organometallic compounds such as Grignard or organolithium reagents. In comparison, C-C and C-H bond activations have facilitated the development of new catalytic processes without the need of using halides or main-group metal reagents. As a result, these reactions not only extend homogeneous catalysis to a much broader range of available starting materials, but can also reduce the generation of undesired salt waste and are therefore more environmentally friendly. Thus, a major focus for our catalyst design is to develop new catalytic processes that feature high atom-efficiency, reduced waste production and mild reaction conditions to minimize harmful impacts on the environment. We are actively seeking synthetic applications of our catalytic methods including asymmetric catalysis, drug development, and material synthesis.

A major theme of our research program is the design, synthesis, and structural characterization of novel organometallic complexes proposed as reactive intermediates in homogeneous catalysis. The elementary (single-step) reactions of these isolated complexes will be subjected to detailed mechanism investigations using NMR kinetic methods, isotope labeling studies, and DFT calculations. These stoichiometric studies will elaborate structure-reactivity correlations in catalysis and provide insights into fundamentals of organometallic chemistry. A variety of methodologies for organometallic synthesis and kinetic studies have been successfully explored in our lab and we will continue to extend our synthetic expertise for ligand and catalyst development. Through collaborations with computational chemists, we also utilize DFT calculations to provide mechanistic details (e.g. structures and free energies of transient reactive intermediates and transition states) that are elusive to experimental methods.

Our current research activities are directed towards the following main projects: (1) Catalytic decarboxylation and reaction mechanism study; (2) Domino catalytic reactions by C-H bond activation and C-C coupling; (3) Atom-efficient catalytic methods for N-heterocycle synthesis; (4) Biomass-based monomer synthesis for sustainable polymer materials.

 

Student Training

Our research bridges areas of organic synthesis, inorganic and organometallic synthesis, homogeneous catalysis, and reaction mechanism studies. It provides interdisciplinary research training and career preparation at undergraduate, graduate, and postdoctoral levels. Students will have opportunities to disseminate their research results in peer-reviewed journals and at domestic and international scientific meetings.

 

Publications

Selected Recent Publications

Kilaru, P.; Acharya, S.; Zhao, P. “A tethering directing group strategy for ruthenium-catalyzed intramolecular alkene hydroarylation,” Chem. Commun. 2018, 54, 924-927. Link.


Zhang, J.; Shrestha, R.; Hartwig, J. F.; Zhao, P. “A Decarboxylative Approach for Regioselective Hydroarylation of Alkynes,” Nat. Chem. 2016, 8, 1144-1151. Link.


Manan, R. S.; Zhao, P. “Merging Rhodium-Catalyzed C-H Activation and Hydroamination in a Highly Selective [4+2] Imine/Alkyne Annulation,” Nat. Commun. 2016 (doi: 10.1038/ncomms 11506). Link.


Manan, R. S.; Kilaru, P.; Zhao, P. “Nickel-Catalyzed Hydroimination of Alkynes,” J. Am. Chem. Soc. 2015, 137, 6136-6139. Link.


Zhang, J.; Ugrinov, A.; Zhang, Y.; Zhao, P. “Exploring Bis-Cyclometalated Ru(II) Complexes as Active Catalyst Precursors: Room-Temperature Alkene-Alkyne Coupling for 1,3-Diene Synthesis,” Angew. Chem. Int. Ed. 2014, 53, 8437-8440. Link.


b) Refereed Papers Published from NDSU [Citing Number via Google Scholar as of 06/30/2020]
1. Kilaru, P.; Acharya, S.; Zhao, P.* “A tethering directing group strategy for ruthenium-catalyzed
intramolecular alkene hydroarylation,” Chemical Communications 2018, 54, 924-927. [11]
2. Zhang, J.; Shrestha, R.; Hartwig, J. F.*; Zhao, P.* “A Decarboxylative Approach for Regioselective
Hydroarylation of Alkynes,” Nature Chemistry 2016, 8, 1144-1151. [65]
3. Manan, R. S.; Zhao, P.* “Merging Rhodium-Catalyzed C-H Activation and Hydroamination in a Highly Selective [4+2] Imine/Alkyne Annulation”, Nature Communications 2016 (doi: 10.1038/ncomms11506). [20]
4. Xu, Y.; Yang, X.; Zhao, P.; Yang, Z.; Yan, C.; Guo, B.; Qian, S. Y.* “Knockdown of delta-5- desaturase promotes the anti-cancer activity of dihomo-γ-linolenic acid and enhances the efficacy of chemotherapy in colon cancer cells expressing COX-2,” Free Radical Biology and Medicine 2016, 96, 67-77. [14]
5. Manan, R. S.; Kilaru, P.; Zhao, P.* “Nickel-Catalyzed Hydroimination of Alkynes,” Journal of the American Chemical Society 2015, 137, 6136-6139. [30]
6. Zhang, J.; Ugrinov, A.; Zhang, Y.*; Zhao, P.* “Exploring Bis-Cyclometalated Ru(II) Complexes as Active Catalyst Precursors: Room-Temperature Alkene-Alkyne Coupling for 1,3-Diene Synthesis,” Angewandte Chemie International Edition 2014, 53, 8437-8440. [19]
7. Zhang, J.; Liu, J.-F.; Ugrinov, A.; Pillai, A. F.; Sun, Z.-M.*; Zhao, P.* “Methoxy-Directed Aryl-to- Aryl 1,3-Rhodium Migration,” Journal of the American Chemical Society 2013, 135, 17270-17273. [35]
8. Zhang, J.; Ugrinov, A.; Zhao, P.* “Ru(II)-Catalyzed Mild [3+2] Carbocyclization with Aromatic N- H Ketimines and Internal Alkynes Using N-Heterocyclic Carbene (NHC) Ligands.” Angewandte Chemie International Edition 2013, 52, 6681-6684. [105]
9. Sule, N.; Singh, R. K.; Zhao, P.; Srivastava, D. K.* “Probing the metal ion selectivity in methionine aminopeptidase via changes in the luminescence properties of the enzyme bound europium ion.” Journal of Inorganic Biochemistry 2012, 106, 84-89. [9]
10. Sun, Z.-M.; Zhang, J.; Manan, R. S.; Zhao, P.* “Rh(I)-Catalyzed Olefin Hydroarylation with Electron-Deficient Perfluoroarenes.” Journal of the American Chemical Society 2010, 132, 6935- 6937. [85]
11. Sun, Z.-M.; Zhang, J.; Zhao, P.* “Rh(I)-Catalyzed Decarboxylative Transformations of Arenecarboxylic Acids: Ligand- and Reagent-Controlled Selectivity towards Hydro-decarboxylation or Heck-Mizoroki Products.” Organic Letters 2010, 12, 992-995. [113]
12. Sun, Z.-M.; Chen, S.-P.; Zhao, P.* “Tertiary Carbinamine Synthesis by Rhodium-Catalyzed [3+2] Annulation of N-Unsubstituted Aromatic Ketimines and Alkynes.” Chemistry – A European Journal 2010, 16, 2619-2627. [136]
13. Sun, Z.-M.; Zhao, P.* “Rhodium-Mediated Decarboxylative Conjugate Additions of Arylcarboxylic Acids: Stoichiometric Investigation and Catalysis Development.” Angewandte Chemie International Edition 2009, 48, 6726-6730. [100]


c) Granted Patent from Research at NDSU
Qian, Y.; Zhao, P.; Yan, C. “Tricyclic compounds for inhibition of delta-5-desaturase (D5D) and treatment of cancer and inflammation”. U.S. Pat. Appl. Publ. (2019), US 20190070193 A1 20190307.


d) Refereed Papers Published prior to NDSU (Ph.D. and Postdoctoral Research)
1. Zhao, P.; Hartwig, J. F.* “Insertions of Ketones and Nitriles into Organorhodium(I) Complexes and -Hydrocarbyl Eliminations from Rhodium(I) Alkoxo and Iminyl Complexes.” Organometallics 2008, 27, 4749-4757.
2. Zhao, P.; Incarvito, C. D.; Hartwig, J. F.* “Directly Observed Transmetalation from Boron to Rhodium. -Aryl Elimination from Rh(I) Arylboronates and Diarylborinates.” Journal of the American Chemical Society 2007, 129, 1876-1877.
3. Zhao, P.; Incarvito, C. D.; Hartwig, J. F.* “Carbon-Oxygen Bond Formation between a Terminal Alkoxo Ligand and a Coordinated Olefin. Evidence for Olefin Insertion into a Rhodium Alkoxide.” Journal of the American Chemical Society 2006, 128, 9642-9643.
4. Zhao, P.; Incarvito, C. D.; Hartwig, J. F.* “Direct Observation of -Aryl Eliminations from Rh(I) Alkoxides.” Journal of the American Chemical Society 2006, 128, 3124-3125.
5. Zhao, P.; Krug, C.; Hartwig, J. F.* “Transfer of Amido Groups from Isolated Rhodium(I) Amides to Alkenes and Vinylarenes.” Journal of the American Chemical Society 2005, 127, 12066-12073.
6. Zhao, P.; Hartwig, J. F.* “-Aryl Eliminations from Rh(I) Iminyl Complexes.” Journal of the American Chemical Society 2005, 127, 11618-11619.
7. Zhao, P.; Condo, A.; Keresztes, I.; Collum, D. B.* “Reaction of Ketones with Lithium Hexamethyldisilazide: Competitive Enolizations and Additions.” Journal of the American Chemical Society 2004, 126, 3113-3118.
8. Zhao, P.; Lucht, B. L.; Kenkre, S.; Collum, D. B.* “Lithium Hexamethyldisilazide-Mediated Ketone Enolization: The Influence of Hindered Dialkyl Ethers and Isostructural Dialkylamines on Reaction Rates and Mechanisms.” Journal of Organic Chemistry 2004, 69, 242-249.
9. Zhao, P.; Collum, D. B.* “Ketone Enolization by Lithium Hexamethyldisilazide: Structural and Rate Studies of the Acceleration Effects of Trialkylamines.” Journal of the American Chemical Society 2003, 125, 14411-14424.
10. Zhao, P.; Collum, D. B.* “Lithium Hexamethyldisilazide/Triethylamine-Mediated Ketone Enolization: Remarkable Rate Accelerations Stemming from a Dimer-Based Mechanism.” Journal of the American Chemical Society 2003, 125, 4008-4009.
e) Book Chapters Published prior to NDSU (Postdoctoral Research)
Zhao, P.; Hartwig, J. F. “Late-Metal-Amido Complexes” and “Transition Metal Complexes with Anionic Oxygen Ligands” in Organotransition Metal Chemistry: from Bonding to Catalysis; Hartwig, J. F. University Science Books, 2010.

 

Associate Professor

BS, Peking (Beijing) University, 1997
PhD, Cornell University, 2004
Postdoctoral Fellow, Yale University, 2004-2006
Postdoctoral Fellow, University of Illinois at Urbana-Champaign, 2006-2007

Office: 255A Dunbar

tel 701-231-8992
fax 701-231-8831

Pinjing.Zhao@ndsu.edu

Zhao Group Home Page