研究领域

Inorganic/Organic/Organometallic

The Collum group studies how aggregation and solvation dictate the reactivity and selectivity of organolithium compounds commonly used by synthetic chemists in both academia and the pharmaceutical industry. A combination of spectroscopic, kinetic, and computational methods bridge organic, organometallic, and analytical chemistry. Research The importance of organolithium reagents in organic chemistry is indisputable. Reports of the effects of solvents, reaction temperatures, additives, internal coordinating functionalities, electrophile structures, and substituents on product distributions pervade the literature. Nevertheless, complexities resulting from aggregation and solvation render our understanding of the origins of the reactivities and selectivities limited at best. Our group investigates the structural and mechanistic basis of selectivity using a range of spectroscopic, kinetic, and computational methods. A number of projects are in collaboration with pharmaceutical process groups.

近期论文

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“Solution Structures of Lithium Amino Alkoxides Used in Highly Enantioselective 1,2-Additions.” Bruneau, A. M.; Liou, L.; Collum, D. B. J. Am. Chem. Soc. 2014, 136, 2885-2891. “Structure Determination Using the Method of Continuous Variations: Lithium Phenolates Solvated by Protic and Dipolar Aprotic Ligands.” Tomasevich, L. L.; Collum, D. B. J. Org. Chem. 2013, 78, 7498-7507. “Method of Continuous Variations: Applications of Job Plots to the Study of Molecular Associations in Organometallic Chemistry.” Renny, J. S.; Tomasevich, L. L.; Tallmadge, E. H.; Collum, D. B. Angew. Chem., Int. Ed. 2013, 52, 11998-12013. “Enediolate-Dilithium Amide Mixed Aggregates in the Enantioselective Alkylation of Arylacetic Acids: Structural Studies and a Stereochemical Model.” Ma, Y.; Stivala, C. E.; Wright, A. M.; Hayton, T.; Liang, J.; Keresztes, I.; Lobkovsky, E.; Collum, D. B.; Zakarian, A. J. Am. Chem. Soc. 2013, 135, 16853-16864. “Lithium Diisopropylamide-Mediated Ortholithiation of 2-Fluropyridines: Rates, Mechanisms, and the Role of Autocatalysis.” Gupta, L.; Hoepker, A. C.; Ma, Y.; Viciu, M. S.; Faggin, M. F.; Collum, D. B. J. Org. Chem. 2013, 78, 4214-4230. “Azaaldol Condensation of a Lithium Enolate Solvated by N,N,N’,N’-Tetramethylethylenediamine: Dimer Based 1,2-Addition to Imines.” De Vries, T. S.; Bruneau, A. M.; Liou, L. R.; Subramanian, H.; Collum, D. B. J. Am. Chem. Soc. 2013, 135, 4103-4109. “Computational Studies of Lithium Diisopropylamide Deaggregation.”Hoepker, A. C.; Collum, D. B. J. Org. Chem. 2011. “Regioselective Lithium Diisopropylamide-Mediated Ortholithiation of 1-Chloro-3-(trifluoromethyl)benzene: Roleof Autocatalysis, Lithium Chloride Catalysis, and Reversibility.”Hoepker, A. C., Gupta, L., Ma, Y., Faggin, M. F., Collum, D. B. J. Am. Chem. Soc. 2011, 133, 7135-7151. “Reaction of Lithium Diethylamide with an Alkyl Bromide and Alkyl Benzenesulfonate: Origins of Alkylation,Elimination, and Sulfonation.”Gupta, L., Ramirez, A., Collum, D. B. J. Org. Chem. 2010, 75, 8392-8399. “1,4-Addition of Lithium Diisopropylamide to Unsaturated Esters: Role of Rate-Limiting Deaggregation, Autocatalysis, Lithium Chloride Catalysis, and Other MIxed Aggregation Effects.”Ma, Y.; Hoepker, A. C.; Gupta, L.; Faggin, M. F.; Collum, D. B. J. Am. Chem. Soc. 2010, 132, 15610. “Experimental Characterization and Computational Study of Unique C,N-Chelated Lithium Dianions.”Gruver, J. M.; West, S. P.; Collum, D. B.; Sarpong, R. J. Am. Chem. Soc. 2010, 132, 13213. “Mechanism of Lithium Diisopropylamide-Mediated Substitution of 2,6-Difluoropyridine.”Viciu, M. S.; Gupta, L.; Collum, D. B. J. Am. Chem. Soc. 2010, 132, 6361. “Lithium Phenolates Solvated by Tetrahydrofuran and 1,2-Dimethoxyethane: Structure Determination Using the Method of Continuous Variation”.De Vries, T. S.; Goswami, A.; Liou, L. R.; Gruver, J. M.; Jayne, E.; Collum, D. B. J. Am. Chem. Soc. 2009, 131, 13142. “Lithium Diisopropylamide-Mediated Ortholithiations: Lithium Chloride Catalysis”.Gupta, L.; Hoepker, A. C.; Singh, K. J.; Collum, D. B. J. Org. Chem. 2009, 74, 2231. “Structures of β-Amino Ester Enolates: New Strategies Using the Method of Continuous Variation”.Liou, L. R.; McNeil, A. J.; Toombes, G. E. S.; Collum, D. B. J. Am. Chem. Soc. 2008, 130, 17334. “Autocatalysis in Lithium Diisopropylamide-Mediated Ortholithiations”.Singh, K. J.; Hoepker, A. C.; Collum, D. B. J. Am. Chem. Soc. 2008, 130, 18008. “Anionic Snieckus-Fries Rearrangement: Solvent Effects and Role of Mixed Aggregates”.Riggs, J. C.; Kanwal, S. J.; Ma, Y.; Collum, D. B. J. Am. Chem. Soc. 2008, 130, 13709. “Solution Structures of Lithium Enolates, Phenolates, Carboxylates, and Alkoxides in the Presence of N,N,N’,N’-Tetramethylethylenediamine: A Prevalence of Cyclic Dimers”.Gruver, J. M.; Liou, L. R.; McNeil, A. J.; Ramirez, A.; Collum, D. B. J. Org. Chem. 2008, 73, 7743. “Synthesis of a 7-Azaindole by Chichibabin Cyclization: Reversible Base-Mediated Dimerization of 3-Picolines”.Ma, Y.; Breslin, S.; Keresztes, I.; Lobkovsky, E.; Collum, D. B. J. Org. Chem. 2008, 73, 9610. “Lithium Hexamethyldisilazide-Mediated Enolizations: Influence of Triethylamine on E/Z Selectivities and Enolate Reactivities ”.Godenschwager, P. F.; Collum, D. B. J. Am. Chem. Soc. 2008, 130, 8726.