R. Daniel Little

Research Professor

Contact Phone

(805) 893-3693

Office Location

3649C/D PSB-N

Specialization

Education

Dan Little received his BS degree in chemistry and mathematics from the University of Wisconsin in Superior, and then moved to the UW – Madison where he studied under Howard Zimmerman and received his PhD in 1974. Following a year and a half of postdoctoral study at Yale (with Jerry Berson), Dan accepted a position at UCSB where he is a professor and a past department chair. His interests span a wide range of topics that presently include electron transfer, green electrochemistry, applications of redox chemistry to synthesis, redox mediated processes, the development of polymer and dendrimer-based redox mediators, applications of quantum mechanical tools to aid in understanding redox chemistry, and the relationship between redox reactions and the expression of bioactivity.

Research

Research Group Website: http://www.chem.ucsb.edu/~little_group/

Research Objective

• To obtain a fundamental understanding of the reactive intermediates produced using mediated, electrocatalytic processes well as their chemical transformations. We are developing the chemistry of both cation and anion radicals and are particularly interested in further explorations of remote regiochemical control, and upon applying our knowledge to the synthesis of natural products.

• In an effort to reduce costs and waste, we are designing, synthesizing and testing recyclable, polymer bound redox mediators to affect both oxidative as well as reductive processes. Other efforts to carry out green electrochemistry are being conducted in collaboration with Professor Bernardo Frontana-Uribe from UNAM in Mexico City and the Institute for Green Chemistry that is located in Toluca.

• Investigation of the redox chemistry of fulvenes with an eye toward using the chemistry to construct a variety of different rings systems, as well as using it to provide a simple, one-step synthetic route to metallocene co-catalysts.

• Investigation of the chemistry of cyclic peroxides.

Publications

 

•     Li, L.; Jiang, Y.; Zeng, C-C; Hu, L-M.; Tian, H-Y.; Lam, C. M.; Little, R. D.  Aromatic C-H bond functionalization induced by electrochemically in situ generated tris(p-bromophenyl)aminium (TBPA) radical cation: cationic chain reactions of electron-rich aromatics with enamides, J. Org. Chem. 2015, 80(21), 11021-11030; DOI: 10.1021/acs.joc.5b02222

•     Chen, J.; Yan, W-Q.; Lam, M.; Zeng, C-C.; Hu, L-M.; Tian, H-Y.; Little, R.D. Electrocatalytic Aziridination of Alkenes Mediated by n-Bu4NI: A Radical Pathway Org. Lett. 2015, http://dx.doi.org/10.1021/acs.orglett.5b00083

•     Yoo, S. J.; Li, Long-Ji; Zeng, C-C.; Little, R. D. Polymeric Ionic Liquid and Carbon Black Composite as a Reusable Supporting Electrolyte: Modification of the Electrode Surface, Angewandte Chemie, Int. Ed. 2015, http://dx.doi.org/10.1002/anie.201410207 in the International Edition and http://dx.doi.org/10.1002/ange.201410207 in the German Edition.

•     Gbur, R. K.; Little, R. D. Electrosynthesis of Bioactive Materials, in Organic Electrochemistry (5th edition), B. Speiser, O. Hammerich (Eds.), 2015, Taylor & Francis.

•     Utley, J. H. P.; Little, R. D.; Nielsen, M. F. Reductive Coupling, in Organic Electrochemistry (5th edition), B. Speiser, O. Hammerich (Eds.), 2015, Taylor & Francis.

•     Lu, N-N.; Zhang, N-T.; Zeng, C-C.; Hu, L-M.; Yoo, S.J.; Little, R. D. Electrochemically induced ring-opening/Friedel-Crafts arylation of chalcone epoxides catalyzed by a triarylimidazole redox mediator, J. Org. Chem. 2015, 80, 781-789 http://doi.org/10.1021/jo5022184

•     Gao, W-J.; Li, W-C.; Zeng, C-C.; Tian, H-Y.; Hu, L-M.; Little, R. D. Efficient Electrochemical Oxidative Aminations of Benzoxazoles using Alkylammonium Halides as Redox Catalysts J. Org. Chem. 2014, 79 (20), 9613–9618, http://dx.doi.org/10.1021/jo501736w

•     N. Lu, S. Joon Yoo, Long-Jie Li, C.C. Zeng, R. D. Little, A comparative study of organic electron transfer redox mediators: electron transfer kinetics for triarylimidazole and triarylamine mediators in the oxidation of 4-methoxybenzyl alcohol Electrochim. Acta, 2014, 142, 254-260

•     Xiao, H-L.; Zeng, C-C.; Tian, H-Y.; Hu, L-M.; Little, R.D, Electrochemical synthesis of 3,5-disubstituted isoxazoles, J. Electroanal. Chem. 2014, 727, 120-124

•     Francke, R.; Little, R. D. Redox Catalysis in Organic Electrosynthesis: Basic Principles and Recent Developments, Chem. Soc. Rev. 2014, 43, 2492–2521 (front cover). [DOI: 10.1039/C3CS60464K]

•     Francke, R.; Little, R. D. Optimizing Electron Transfer Mediators Based on Arylimidazoles by Ring Fusion: Synthesis, Electrochemistry and Computational Analysis of 2-Aryl-1-methyl-phenanthro[9,10-d]imidazoles, J. Am. Chem. Soc. 2014, 136, 427–435.[DOI: 10.1021/ja410865z]

•     Li, C.; Zeng, C.-C.; Hu, L.-M.; Yang, F.-L.; Little, R. D. Electrochemically induced C-H functionalization using bromide ion/TEMPO dual redox catalysts in a two-phase electrolyte system, Electrochim. Acta 2013, 114, 560-566. [DOI: 10.1016/j.electacta.2013.10.093]

•     Li, W.-C.; Zeng, C.-C.; Hu, L.-M.; Tian, H.-Y.; Little, R. D. Efficient indirect electrochemical synthesis of 2-substituted benzoxazoles using NaI as a mediator Adv. Synth. Catal. 2013, 355, 2884–2890. [DOI: 10.1002/adsc.201300502]

•     Day, D. R.; Jabaiah, S.; Jacobs, R. S.; Little, R. D. Cyclodextrin Formulation of the Marine Natural Product Pseudopterosin A Uncovers Optimal Pharmacodynamics in Proliferation Studies of Human Umbilical Vein Endothelial Cells, Mar. Drugs, 2013, 11, 3258-3271. [DOI: 10.3390/md11093258]

•     Zhang, N.-T.; Zeng, C.-C.; Lam, C. M.; Gbur, R. K.; Little, R. D. Triarylimidazole Redox Catalysts: Electrochemical Analysis and Empirical Correlations, J. Org. Chem. 2013, 78, 2104–2110. [DOI: 10.1021/jo302309m ]

•     Xiao, H.-L.; Yang, C.-W.; Zhang, N.-T.; Zeng, C.-C.; Hu, L.-M.; Tian, H.-Y.; Little, R. D. Electrochemical oxidation of aminophenols in the presence of benzenesulfinate, Tetrahedron 2012, 69, 658-663. [DOI: 10.1016/j.tet.2012.11.005 ]

•     Little, R. D. Anodic Substitutions, in Encyclopedia of Applied Electrochemistry, R. F. Savinell, K.-I. Ota and G. Kreysa, (Eds), 2012, Springer, New York.

•     Zeng, C.-C.; Zhang, N.-T.; Lam, C. M.; Little, R. D. Novel triarylimidazole redox catalysts: synthesis, electrochemical properties and applicability to electrooxidative C-H activation, Org. Lett., 2012, 14, 1314-1317. [DOI: 10.1021/ol300195c ]

•     Gbur, R.; Little, R. D. Unveiling the Role of Molecule-Assisted Homolysis: A Mechanistic Probe into the Chemistry of a Bicyclic Peroxide, J. Org. Chem. 2012, 77, 2134-2141. [DOI: 10.1021/jo300297u ]