Chemistry at Illinois University of Illinois at Urbana-Champaign

Peter Beak

Center for Advanced Study Professor Emeritus

Professor Beak received his B.A. from Harvard University in 1957 and his Ph.D. from Iowa State University in 1961 and then joined the faculty at Illinois. Professor Beak's research interests are in synthetic, structural and mechanistic organic chemistry, new reaction processes, synthetic methodology, and reactive intermediates.

Research

We focus on designing, discovering, developing, and understanding new reactions. We follow an exploratory study of a postulated reaction pathway or hypothetical reaction intermediate by developing the synthetic potential of the reaction and investigating the reaction mechanism. We are interested in processes that are synthetically useful and mechanistically interesting.

In organometallic chemistry we investigate the role of complexes in the formation and reactions of organolithium reagents, and the use of complexed species in enantioselective reactions. We hypothesize that a complex induced proximity effect is operating in many reactions. This work has led us to study dipole stabilized carbanions, ß-lithiated amides, substituted allyl anions, and benzylic- and ortho-lithiated aromatics.

The synthetic consequences of this work include the use of alpha-lithiated amides as alpha-lithioamine synthetic equivalents, and of ß-lithiated amides as homoenolates in regio-, diastereo-, and enantioselective sequences, with emphasis on enantioselective syntheses of amines, enantioselective substitutions of benzylic systems, and synthetic uses of dilithiated species. In other synthetic investigations we are exploring new reaction processes.

In the physical-organic area we are using the endocyclic restriction test to investigate the geometry of reactions at nonstereogenic atoms or groups of atoms. The geometry of atom transfermay be evaluated by investigating systems in which the incoming and leaving groups are joined by a molecular tether. The size of the ring allowed by the tether for an intramolecular reaction in the transfer of the atom between the groups limits the available reaction geometry. If the transfer has geometrical requirements that cannot be met intramolecularly in the transition structure, the reaction becomes intermolecular. We are investigating experimental distinctions between these possibilities and evaluating alternative mechanisms of concerted, associative, or dissociative modes. We have reported on this approach for investigating the geometry of reactions at nitrogen, oxygen, phosphorous, sulfur, and the halogens. In addition, we are studying kinetic and product isotope effects to distinguish the mechanisms of reactions, investigating the structures of synthetically useful organolithium reagents, and investigating models for the enzyme OMP-decarboxylase.

Publications

Dynamic Thermodynamic Resolution: Advantage by Separation of Equilibration and Resolution (with W. K. Lee and Y. S. Park) Acc. Chem. Res., 42 (2), 224 (2009).

The Endocyclic Restriction Test: The Geometries of Nucleophilic Substitutions at Sulfur(VI) and Sulfur(II) (with S. G. Jarboe and M. S. Terrazas), J. Org. Chem., 73 (24), 9627 (2008).

Asymmetric Syntheses of 3,4-Substituted Tetrahydroquinoline Derivatives by (-)Sparteine-Mediated Dynamic Thermodynamic Resolution of 2-(a-Lithiobenzyl)-N-pivaloylaniline (with Y. Kim and Y. S. Park) Synlett, 22, 3805 (2006).

Dynamic Thermodynamic Resolution: Solvent Effects, Mechanism, and an Asymmetric 3,4,5-Substituted Benzazapine Synthesis (with Y. S. Park, E. G. Yum, and A. Basu) Organic Letters, 8, 2667 (2006).

Asymmetric Synthesis of 4,5,6-and 3,4,5,6-Substituted Azepanes by a Highly Diastereoselective and Enantioselective Lithiation-conjugate Addition Sequence (with S. J. Lee) J. Am. Chem. Soc., 128, 2178 (2006).

Asymmetric Lithiation-Substitution Sequences of Substituted Allyl Amines, (with S. J. Lee and D. K. Kim), J. Org. Chem., 70, 5376 (2005).

Awards

  • Silver Medal RSC
  • CAS Professor of Chemistry
  • Fellow, American Academy of Arts & Sciences
  • Member, National Academy of Sciences
  • Alfred P. Sloan Fellowship
  • Guggenheim Fellowship
  • ACS Arthur C. Cope Scholar
  • Mosher Award
  • Fellow, AAAS
  • Henry Gilman Award
  • Gassman Award

Highlights

Patents

Photo of Peter Beak