Current Research
Our present research studies are focused on the influence that vinyl fluorine atoms have on the product regiochemistry of stepwise ionic electrophilic reactions. We are also probing the synthetic reactions for making fluorinated beta-lactams. Beta-Lactams are a class of antibiotics. Fluorine substituted beta-lactams have not been studied due to a lack of synthetic methods available to make them.
Areas of Research
Dr. Shellhamer’s research focus is primarily on organofluorine chemistry. Organofluorine molecules are an important class of compounds in medicinal chemistry. There are a limited number of reactions available to the synthetic chemist for incorporating fluorine into organic molecules. We have developed new reactions with xenon difluoride and investigated the synthetic parameters of dialkylaminosulfur trifluoride reagents. Our research on new methods to generate interhalogen fluorides present another useful reaction to introduce fluorine into organic molecules. Dr. Shellhamer’s recent research is on ionic reactions of halogen systems with perfluoroalkylalkenes and hydrocarbon fluoroalkenes to determine the effect fluorine has on the symmetry of halonium ion intermediates.
Click to view Dr. Shellhamer's publications (1988-present)
We developed a photochemical reaction and alkoxyfluorination reactions with xenon difluoride. Published papers describing these studies include:
"A Mild Method for introducing iodine Monofluoride into Alkenes and Iodination of Aromatics Using Xenon Difluoride," D.F. Shellhamer, B.C. Jones, B.J. Pettus, T.L. Pettus, J.M. Stringer, V.L. Heasley. J. Fluor. Chem., 88, 37, 1998
"Addition Reactions of Electronegative Alkoxyxenon Fluorides with Alkenes," M. L. Druelinger, D. F. Shellhamer, R. D. Chapman, S. A. Shackelford, M. E. Reiner, S. L. Carter, R. P. Callahan and C. R. Youngstrom, Journal of the Chemical Society, London, Perkin Transactions 2, 787, 1997.
"The Fluorination of Cyclopentadiene and 3,4-Epoxycyclopentene," D. F. Shellhamer, M. C. Chiaco, K. M. Gallego, W. S. C. Low, B. Carter, V. L. Heasley, and R. D. Chapman, Journal of Fluorine Chemistry, 72, 83, 1995.
"Reaction of Alkylhypochlorites and Xenon Difluoride with Cyclohexene," D. F. Shellhamer, M. J. Horney, A. L. Toth and V. L. Heasley, Tetrahedron Letters, 33, 6903, 1992.
" The Regioselectivity in the Addition of Alkoxyxenon Fluorides," D. F. Shellhamer, S. L. Carter, R. H. Dunham, S. N. Graham, V. L. Heasley, R. D. Chapman and M. L. Druelinger, Journal of the Chemical Society, London, Perkin Transactions 2, 159, 1989 and references therein.
"Radical Additions of Xenon Difluoride to cis- and trans-1-Phenylpropenes: Comparison with Trichloroamine and Iodobenzene Dichloride," D. F. Shellhamer, M. L. Ragains, B. T. Gipe, V. L. Heasley and G. E. Heasley, The Journal of Fluorine Chemistry, 20, 13, 1982.
We investigated the stereochemistry of these reagents and their reactions with dialcohols and cyclopentadiene epoxide. Published papers include:
"Reaction of Aminosulfur Trifluorides with Alcohols: Inversion vs. Retention", D. F. Shellhamer, A. A. Briggs, B. M. Miller, J. M. Prince, D. H. Scott and V. L. Heasley, Journal of the Chemical Society, London, Perkin Transactions 2, 973, 1996.
"Reaction of Diethylaminosulfur Trifluoride with Diols", D. F. Shellhamer, D. T. Anstine, K. M. Gallego, B. R. Ganesh, A. A. Hanson, K. A. Hanson, R. D. Henderson, J. M. Prince and V. L. Heasley, Journal of the Chemical Society, London, Perkin Transactions 2, 861, 1995.
"The Fluorination of Cyclopentadiene and Epoxycyclopentene", D. F. Shellhamer, M. C. Chiaco, K. M. Gallego, W. S. C. Low, B. Carter, V. L. Heasley and R. D. Chapman. Journal of Fluorine Chemistry, 72, 83, 1995.
"Facile Addition of Poorly Nucleophilic Alcohols to Unactivated Alkenes", D. F. Shellhamer, R. P. Callahan, M. L. Druelinger, R. D. Chapman, and V. L. Heasley. Synthesis, 1997, 9, 1056.
Some of our earlier work to generate interhalogen fluorides include:
“Symmetry of Chloronium Ions from Ionic Reactions of Chlorine, Chlorine Monofluoride Gas and Chlorine Monofluoride Complex with Terminal Alkenes,” D.F. Shellhamer, P.K. Titterington*, V.L. Heasley. J. Fluorine Chem., 124, 17, 2003.
"Generating Interhalogen Fluorides under Mild Conditions: A Comparison of Sluggish and Reactive Interhalogen Fluorides," D.F. Shellhamer, M.J. Horney, B.J. Pettus, T.L. Pettus, J.M. Stringer, and V.L. Heasley. J. Org. Chem., 64, 1094, 1999.
"A Mild Method for introducing iodine Monofluoride into Alkenes and Iodination of Aromatics Using Xenon Difluoride," D.F. Shellhamer, B.C. Jones, B.J. Pettus, T.L. Pettus, J.M. Stringer, V.L. Heasley. J. Fluorine. Chem., 88, 37, 1998.
"Generating Interhalogen Fluorides," D. F. Shellhamer, B. C. Jones, B. J. Pettus, T. L. Pettus, J. M. Stringer, V. L. Heasley, Robert G. Syvret and John M. Dobrolsky, Jr. Oral presentation at The 13th Winter Fluorine Conference at St. Petersburg Beach, FL on January 23, 1997.
"Reaction of Alkylhypohalites and Xenon Difluoride with Cyclohexene," D. F. Shellhamer, M. J. Horney, A. L. Toth and V. L. Heasley, Tetrahedron Letters, 33, 6903, 1992.
Oral presentation: "A Mechanistic Study on the Generation of Interhalogen Fluorides: A Search for Reaction Intermediates," B.J. Pettus and D.F. Shellhamer. Presented by B.J. Pettus at the 1997 Southern California Undergraduate Research Conference in Chemistry and Biochemistry on April 26, 1997 at California State University, Northridge, CA.
“Correlation of Calculated Halonium Ion Structures with Experimental Product Distributions from Terminal Alkenes: The Effect of Electron-Withdrawing Fluorine Substituents on the Structure and Charge Localization of Halonium Ions,” D.F. Shellhamer, D.C. Gleason*, V.L. Heasley, and J.J. Lehman. Manuscript in preparation.
“Ionic Reaction of Halogens with Terminal Alkenes: The Effect of Electron-Withdrawing Fluorine Substituents on the Bonding of Halonium Ions,” D.F. Shellhamer, J.L. Allen*, R.D. Allen*, D.C. Gleason*, C. O’Neil Schlosser*, B.J. Powers*, J.W. Probst*, M.C. Rhodes*, A.J. Ryan*, P.K. Titterington*, G.G. Vaughan* and V.L. Heasley. J. Org. Chem., 68, 3932, 2003.
“Symmetry of Chloronium Ions from Ionic Reactions of Chlorine, Chlorine Monofluoride Gas and Chlorine Monofluoride Complex with Terminal Alkenes,” D.F. Shellhamer, P.K. Titterington*, V.L. Heasley. J. Fluorine Chem., 124, 17, 2003.
“Comparison of the Electrophilic and Free-Radical and 1,3-Butadien,” D.F. Shellhamer, D.C. Gleason*, G.G. Vaughan*, A.J. Ryan*, P.K. Titterington*, V.L. Heasley and J.J. Lehman. J. Fluorine Chem., 123, 171, 2003.