Metalation supported by hydrocarbon media: Steric effects on substrate coordination

ORGN 105

Courtney R. Phillips, phillcr1@wku.edu1, Robert Holman, holmrobe@isu.edu2, William S. Brown, brown099@bama.ua.edu3, E. Mullins1, and Seth Dumbris1. (1) Department of Chemistry, Western Kentucky University, Western Kentucky University, Bowling Green, KY 42101, (2) Department of Chemistry, Idaho State University, Box 8023, Pocatello, ID 83209, (3) Department of Chemistry, The University of Alabama, Box 870336, Tuscaloosa, AL 35487-0336
The effect of steric hindrance imparted by a directing metalation group(s) upon directed ortho metalation reactions (DoM) in hydrocarbon media was recently investigated in order to attain mechanistic insights into these reactions. In this work, anisole was found to metalate more than two times more efficiently than does phenetole, and dimethylaniline (DMA) metalates two times more efficiently than does diethylaniline (DEA). Calculations were performed to determine if differences in metalation efficiency are directly related to the acidity of ortho protons. It was found that the relative acidity of the ortho proton is not significantly impacted by steric effects and metalation efficiency cannot be readily explained by simple acid-base interactions. Complexation efficiencies, as determined by the interpretation of NMR spectra, correlate well with metalation efficiencies. We assert that the results of this study can be attributed to some form of Complexed Induced Proximity Effect (CIPE).
 

Heterocycles, Aromatics, Materials, Devices, Switches, Combinatorial Chemistry, Metal-Mediated Reactions
8:00 PM-10:00 PM, Sunday, 13 March 2005 Convention Center -- Hall D, Poster

Division of Organic Chemistry

The 229th ACS National Meeting, in San Diego, CA, March 13-17, 2005