CHED 720 |
| Dipseudoanhydrides are derived from pseudoacid (cyclic oxocarboxylic acids) by dehydration, and unlike conventional carboxylic anhydrides, they exist as diastereomers. The function has few degrees of conformational freedom due to the rigidity of pseudoacyl moieties. And, because of the bulkiness of the pseudoacy group, the conformations of dipseudoanhydrides are restricted to within narrow ranges of two torsional parameters. A few of these structures have been characterized in the solid state by diffraction methods, and in this study, computations at the semi-empirical level have been completed to compare the expected with the experimental conformations. We have investigated (R,R) and (R, S)-bis(isobenzofuran-1-one-3-yl)ethers, (R,R) and (R,S)-bis(3-methylisobenzofuran-1-one-3-yl)ethers, (R,R) and (R,S)-bis(dihydroisobenzopyran-1-one-3-yl)ethers, and (R,R) and (R,S)-bis(4,4-dimethyldihydroisobenzopyran-1-one-3-yl)ethers. In each relevant case, the computed conformations closely model those found in the extant diffraction studies. We acknowledge the support of NSF grant MRI 0618148 and the W. M. Keck Foundation for computational and crystallographic resources. |
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Undergraduate Research Poster Session: Polymer Chemistry
11:00 AM-1:00 PM, Monday, April 7, 2008 Morial Convention Center -- Hall A, Poster
Division of Chemical Education |