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Paul Rablen


Organic Chemistry


  2. Phone: (610) 328-8341
  3. Science Center 292


NIH Postdoctoral Fellow, Yale University, Department of Chemistry
Ph.D., Organic Chemistry, Yale University
M.A., Organic Chemistry, Columbia University
B.A., Chemistry, Haverford College


Chemistry 010 HN, Chemistry 022, Chemistry 122.


​Research in my laboratory focuses on fundamental questions about the relationship between structure, stability, and reactivity in organic compounds, and on questions about the mechanistic pathways of organic reactions. These questions are pursued through the use of ab initio molecular orbital calculations. These quantum mechanical calculations yield quite accurate predictions for the energies, geometries, and spectroscopic properties of stable compounds, intermediates, and even transition structures. There also collaborations with laboratories at other institutions, concerned with such topics as electron transport in peptides and development of malaria therapeutics.
Recent specific topics have included:
  • How the distribution of alkyl groups affects the stability of allyl and pentadienyl carbocations
  • How the multistep carbocation rearrangement involved in the transformation of caryolanol to isoclovene takes place
  • How phenylalanine (in addition to the well-known cases of tyrosine, tryptophan, and histidine) can act as a radical cation "stepping stone" for the transmission of charge (as electron "holes") through a peptide (This project is a collaboration with groups in Fribourg, Switzerland and Melbourne, Australia)
  • Assessment of how well various functional groups might serve as isosteric replacements for a diaryl thioether (which is susceptible to in Vivo degradation) in pharmaceuticals (This project is a collaboration with the Knapp research group at Rutgers University)

Recent Publications

(undergraduate researchers marked with *)

Barrows, Robert D.;  Hammill, Jared T.; Tran, Michael C.; Falade, Mofolusho O.; Rice, Amy L.; Davis, Christopher W.; Emge, Thomas J.; Rablen, Paul R.; Guy, R. Kiplin ; Knapp, Spencer “Evaluation of 1,1-cyclopropylidene as a thioether isostere in the 4-thio-thienopyrimidine (TTP) series of antimalarials” Bioorganic & Medicinal Chemistry 2020, 28, 115758.

Banert, K.; Hagedorn, M.; Heck, M.; Hertel, R.; Ihle A.; Müller, I.; Pester, T.; Shoker, T; Rablen, P. R. “Synthesis of Trialkylamines with Extreme Steric Hindrance and Their Decay by a Hofmann-like Elimination Reaction” J. Org. Chem. 2020, 85, 13630-13643.


Rablen, P. R. “A Procedure for Computing Hydrocarbon Strain Energies Using Computational Group Equivalents, with Application to 66 Molecules” Chemistry 2020, 2, 22, 1-11; doi:10.3390/chemistry2020022.

Wiberg, K. B.; Rablen, P. R. “Increase in Strain Energy during Conversion of []Fenestrane to []Fenestrane: a Method for Estimating the Heats of Formation of Hydrocarbons and Their Derivatives from Ab Initio Energies” J. Org. Chem. 2020, 85, 4981-4987.

Beckmann, P. A.; Rablen, P. R.; Schmink, J.; Szewczyk, S. T.; Rheingold, A. L. “Concomitant Polymorphism in an Organic Solid: Molecular Structure, Crystal Structure, and Intramolecular and Intermolecular Potential Contributions to tert-Butyl and Methyl Group Rotation” ChemPhysChem 2019, 20, 2887-2894.

Le, N. T. L.; Just, J.; Pankauski, J. M.; Rablen, P. R.; Thamattoor, D. M. "The Ring Expansion of Alkylidenecarbenes derived from Lactams, Lactones, and Thiolactones into Strained Heterocyclic Alkynes:  A Theoretical Study" Molecules 2019, 24, 593-618.

Woodside, A. J.;* Smith, M. A.;* Herb, T. M.; Manor, B. C.; Carroll, P. J.; Rablen, P.R.; Graves, C. R. "Synthesis and Characterization of a Tripodal Tris(nitroxide) Aluminum Complex and Its Catalytic Activity toward Carbonyl Hydroboration" Organometallics 2019, 38, 1017-1020.

Wiberg, K. B.; Rablen, P. R. "Atomic Charges" J. Org. Chem. 2018, 83, 15463-15469.

Wiberg, K. B.; Rablen, P. R. "Methoxymethane C–O Bond Strengths:  Do Their Changes Result from Hyperconjugation or Polar Effects?" J. Phys. Chem. A 2018, 122, 6021-6025.

Wiberg, K. B.; Rablen, P. R.; Baraban, J. H. "Butadiene and Heterodienes Revisited" J. Org. Chem. 2018, 83, 8473-8482.

Rablen, P. R. "Acid-catalyzed conversion of caryolan-1-ol to isoclovene:  a computational investigation of the multi-step carbocation rearrangement" Tetrahedron 2018, 74, 3781-3786.

Kirsh, J. M.;* Woodside, A. J.;* Manor, B. C.; Carrol, P. J.; Rablen, P. R.; Graves, C. R. "Synthesis and Characterization of (pyNO–)2GaCl: A Redox-Active Gallium Complex" Inorganics 2018, 6, 50.

Nathanael, J. G.; Gamon, L. F.; Cordes, M.; Rablen, P. R.; Bally, T.; Fromm, K. M.; Giese, B.; Wille, U. "Amide Neighbouring Group Effects in Peptides:  Phenylalanine as Relay Amino Acid in Long-Distance Electron Transfer" ChemBioChem 2018, 19, 922-926.

Rablen, P. R.; Perry-Freer, N. A.* "How the arrangement of alkyl substituents affects the stability of delocalized carbocations" J. Org. Chem. 2018, 83, 4024-4033.

Barrow, R. D.; Blacklock, K. M.; Rablen, P. R.; Khare, S. D.; Knapp, K. "Computational Assessment of Thioether Isosteres" J. Mol. Graph. Model. 2018, 80, 282-292.

Nikolayevskiy, H.; Tun, M. K. M.; Rablen, P. R.; Ben Mamoun, C.; Herzon, S. B. "A complex stereochemical relay approach to the antimalarial alkaloid ocimicide A(1). Evidence for a structural revision" Chemical Science 2017, 8, 4867-4871.

Ma, X.; Dang, H.; Rose, J. A.; Rablen, P. R.; Herzon, S. B. "Hydroheteroarylation of Unactivated Alkenes Using N-Methoxyheteroarenium Salts" J. Am. Chem. Soc. 2017, 139, 5998-6007.

Walker, A. S.; Rablen, P. R.; Schepartz, A. “Rotamer-Restricted Fluorogenicity of the Bis-Arsenical ReAsH” J. Am. Chem. Soc. 2016, 138, 7143-7150.