The central focus of Bill's thesis work was an investigation of the remarkable effect of HMPA on the regioselectivity of the addition of some organolithium reagents to enones and other α,β-unsaturated carbonyl compounds.
He combined spectroscopic studies of the lithium reagents, using the HMPA titration technique of Joe Borst and Bob Dykstra, with product studies, kinetics (more of these done later by Bob Edmonston) , and stereochemistry. He found that there are two factors which control regioselectivity when HMPA was added: the formation of separated ion pairs, and the suppression of lithium catalysis.
Along the way Bill took several interesting detours, including the development of a superb 13C chemical shift thermometer (tris(trimethylsilyl)methane), and an extensive foray into chelated organolithium reagents and triple ions
- "The Origin of Regioselectivity in an Allenyllithium Reagent," Hans J. Reich, Johnathan E. Holladay, J. Derek Mason, William H. Sikorski, J. Am. Chem. Soc. 1995, 117, 12137-12150. (Article) PDF
- "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
- "Triple Ion Formation in Localized Organolithium Reagents," Hans J. Reich, William H. Sikorski, Birgir Ö. Gudmundsson and Robert R. Dykstra, J. Am. Chem. Soc. 1998, 120, 4035-4036. (Communication) PDF
- "The Regioselectivity of Addition of Organolithium Reagents to Enones: The Role of HMPA," Hans J. Reich and William H. Sikorski, J. Org. Chem. 1999, 64, 14-15. (Communication) PDF Supp
- "The Regioselectivity of Addition of Organolithium Reagents to Enones and Enals: The Role of HMPA," William H. Sikorski and Hans J. Reich J. Am. Chem. Soc. 2001, 123, 6527-6535.(Article) PDF Suppl.
- "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
- "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
- "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
- "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