Joseph P. Borst -- PhD 1991

Scientific Career

Thesis Title
Stereochemistry of the Lithium-Tin Exchange. Ion Pair Structure of Lithium Reagent Species in THF/HMPA Solution.
Research Summary Joe's thesis research was concentrated in two principal areas. He followed up on Nancy Phillip's work on the mechanism of the lithium-tin exchange by determining stereochemistry of substitution at the tin center. In ether the reaction occurred with strict retention of configuration, whereas in THF the product was racemized, as expected for an ate-complex mechanism.

He also took a very important observation made by Pat Green, that under suitable conditions it was possible to observe J coupling between lithium and phosphorous in lithium reagent HMPA complexes, and exploited this to determine the solution behavior of a wide variety of lithium reagents in THF-HMPA solutions. This work opened the door to an understanding of lithium reagent solution structure at an unprecedented level of detail, and set the stage for several other thesis projects, especially Bob Dykstra, Bill Sikorski, and Jennifer Thompson.
  1. "Direct Nuclear Magnetic Resonance Spectroscopic Determination of Organolithium Ion Pair Structures in THF/HMPA Solution," H. J. Reich and J. P. Borst, J. Am. Chem. Soc. 1991, 113, 1835. (Communication)

  2. "Mechanism of the Lithium-Tellurium, Lithium Iodine and Lithium-Mercury Exchange Reactions: Hypervalent Tellurium and Iodine Ate Complexes," H. J. Reich, D. P. Green, N. H. Phillips and J. P. Borst, Phosphorus, Sulfur, Silicon, 1992, 67, 83. (Article) PDF

  3. "The Lithium-Tin Exchange Reaction. Stereochemistry at Tin," H. J. Reich, J. P. Borst, M. B. Coplien and N. H. Phillips. J. Am. Chem. Soc. 1992, 114, 6577. (Communication). PDF

  4. "A Nuclear Magnetic Resonance Spectroscopic Technique for the Characterization of Lithium Ion Pair Structures in THF and THF/HMPA Solution," H. J. Reich, J. P. Borst, R. R. Dykstra, D. P. Green J. Am. Chem. Soc. 1993, 115, 8728-41. (Article).PDF

  5. "Trimethylstannyl- and Tributylstannyllithium: Solution Structure in Ether, THF and HMPA," Hans J. Reich, Joseph P. Borst, Robert R. Dykstra, Organometallics 1994, 13, 1. (Communication). PDF

  6. "Solution Ion Pair Structure of 2-Lithio-1,3-Dithianes in THF and THF-HMPA," Hans J. Reich, Joseph P. Borst, Robert R. Dykstra, Tetrahedron 1994, 50, 5869. (Article). PDF

Current Position Research Chemist Sr. I
BASF Corporation

For comments, additions and corrections, send e-mail to Hans J. Reich