Marco followed up on a project begun by Mike Bowe on the configurational stability of secondary organolithium reagents. Marco and Mike found that the Li/Te exchange was uniquely capable of forming secondary alkyllithiums with high stereochemical control. They made the remarkable observation that the rate of configurational inversion was increased both by going to solvents less polar than THF (such as ether), as well as by going to more polar solvents. Very slow epimerization rates were found in THF-PMDTA.
Marco also did some excellent work on the behavior of PhLi solutions, particularly in ether and ether-cosolvent mixtures.
"Stereochemistry of a Cyclohexyllithium Reagent. A Case of Higher Configurational Stability in Strongly Coordinating Media," Hans J. Reich, Marco A. Medina, Michael D. Bowe, J. Am. Chem. Soc. 1992, 114, 11003. (Communication) PDF|
"Aggregation and Reactivity of Phenyllithium Solutions," Hans J. Reich, D. Patrick Green, Marco A. Medina, Wayne S. Goldenberg, Birgir Ö. Gudmundsson, Robert R. Dykstra, and Nancy H. Phillips, J. Am. Chem. Soc. 1998, 120, 7201-7210. (Article)PDF Suppl.
Scientist in the Chemical Synthesis Operation|
Pharmacia & Upjohn Caribe