Aaron W. Sanders -- PhD 2001

Scientific Career

Thesis Title I. Addition of Sulfur Stabilized Lithium Regents to Epoxides. II. Rapid Injection NMR spectroscopy. III. Structure of Chelated Aryllithium Reagents.
Research Summary   Aaron carried out an extensive kinetic study of the reaction of epoxides with sulfur-substituted organolithium reagents. He found that the effect of HMPA was very complex. With some lithium reagents addition of HMPA caused large rate increases, with others large rate decreases. Aaron traced the origin of these effects to the ease of ion pair separation. Large rate increases were observed for hard-to-separate ion pairs like 2-lithio-1,3-dithiane, rate decreases were observed for those which were already partly or completely separated in THF solution.

  In the course of the research on the structure and reactivity of organolithium reagents, there were a number of cases where several isomeric structures or aggregates were present. To address the issue of which of these was actually the reactive species in solution Aaron built the first generation of rapid-injection NMR devices (RINMR) which allowed the injection of samples into organolithium solutions (or vice-versa) and the measurement of NMR spectra within a second or two at temperatures down to -140 deg C. Most of his efforts were aimed at investigating the chemistry of the unusual lithium reagent (Me3Si)3CLi, first studied by Bill Sikorski.
  Aaron also made major contributions to working out the details of the solution structure of several chelated aryllithium reagents, most notably he characterized the open dimer and pentacoordinate monomer of PMDTA-complexed 2-methoxymethylphenyllithium, which was first prepared and studied by Wayne Goldenberg.

  Although he did not get to run many experiments on it, Aaron also constructed the rapid injection NMR (RINMR) apparatus, which was improved by Marty Bevan and then very effectively used by Amanda Jones , Kris Kolonko and Kristin Plessel to study previously inaccessible reaction rates of organolithium reagents under non-Curtin-Hammett conditions.
Papers
  1. "Tris(trimethylsilyl)methane as an Internal 13C NMR Chemical Shift Thermometer." William H. Sikorski, Aaron W. Sanders and Hans J. Reich, Magn. Resonan. Chem. 1998, 36, S118-S124. (Article). PDF

  2. "Chelated Aryllithium Reagents -- Ring Size and Chelating Group Effects," Hans J. Reich, Wayne S. Goldenberg, Aaron W. Sanders and C. Christoph Tzschucke Org. Letters 2001, 3, 33-36. (Communication) PDF

  3. "Amine-Chelated Aryllithium Reagents - Structure and Dynamics." Hans J. Reich, Wayne S. Goldenberg, Birgir Ö. Gudmundsson, Aaron W. Sanders, Klaus J. Kulicke, Katya Simon, and Ilia A. Guzei J. Am. Chem. Soc. 2001, 123, 8087-8079. (Article) PDF Suppl.

  4. "Identification and Mechanistic Consequences of Contact and Solvent-Separated Ion Pair Structures in Organolithium Chemistry." Hans J. Reich, Aaron W. Sanders, Martin J. Bevan, Wiliam H. Sikorski, and Robert R. Dykstra Latvian J. Chem. 2002, 93-103. (Article) PDF

  5. "The Effect of HMPA on the Reactivity of Epoxides, Aziridines and Alkyl Halides with Organolithium Reagents," Hans J. Reich, Aaron W. Sanders, Adam T. Fiedler, and Martin J. Bevan, J. Am. Chem. Soc. 2002, 124, 13386-13387. (Communication) PDF Suppl.

  6. "Amine and Ether Chelated Aryllithium Reagents - Structure and Dynamics." Hans J. Reich, Wayne S. Goldenberg, Aaron W. Sanders, Kevin L. Jantzi and C. Christoph Tzschucke, J. Am. Chem. Soc. 2003, 125, 3509 (Article) . PDF Suppl.

  7. "Pyrrolidine Chelated Aryllithium Reagents," Hans J. Reich, Wayne S. Goldenberg and Aaron W. Sanders, ARKIVOC 2004, (xiii) 97-129 (Article) . PDF

  8. "Interconversion of Contact and Separated Ion Pairs in Silyl- and Arylthio-Substituted Alkyllithium Reagents," Hans J. Reich, William H. Sikorski, Jennifer L. Thompson, Aaron W. Sanders, Amanda C. Jones, Org. Lett. 2006, 8, 4003-4006. (Communication) PDF

  9. "Reactivity of Individual Organolithium Aggregates - a RINMR Study of n-Butyllithium and 2-Methoxy-6-(methoxymethyl)phenyllithium," Amanda C. Jones, Aaron W. Sanders, Martin J. Bevan and Hans J. Reich, J. Am. Chem. Soc. 2007, 129, 3492-3493. PDF, Suppl

  10. "Reactivity of the Triple Ion and Separated Ion Pair of Tris(trimethylsilyl)methyllithium with Aldehydes: A RINMR Study," Amanda C. Jones, Aaron W. Sanders, William H. Sikorski, Kristen L. Jansen, Hans J. Reich J. Am. Chem. Soc. 2008, 130, 6060-6061 (communication). PDF, Suppl, DOI

  11. "Multinuclear NMR Study of the Solution Structure and Reactivity of Tris(trimethylsilyl)methyllithium and its Iodine Ate Complex" Hans J. Reich, William H. Sikorski, Aaron W. Sanders, Amanda C. Jones, Kristin N. Plessel J. Org. Chem. 2009, 74, 719-729 (Article) PDF, Suppl, DOI

Current Position Dow Chemical


Aaron in the lab, ca 1998


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