ORGN 97

Solution-state structures of chiral mixed aggregates by Diffusion-Ordered NMR spectroscopy

Deyu Li, Deyu_Li@Brown.edu, Weibin Li, Weibin_Li@brown.edu, and Paul G. Williard, paul_williard@brown.edu. Department of Chemistry, Brown University, 324 Brook Street, Box H, Providence, RI 02912

Mixed aggregates containing chiral lithium amide, n-BuLi or enolate in tol-d8 solution was investigated using DOSY, 6Li, 7Li NMR and other 2D NMR techniques. Mixed 2:1 trimeric complexes were confirmed as the major species as the stoichiometry approached 0.5 equivalents of n-BuLi or enolate to 1 equivalent of lithium amide. DOSY spectra at 25 or -78 °C showed clear separations between these lithium aggregates and other internal references in the solutions. The correlation between log D and log FW of the linear least squares fit to reference points of all components in the mixture is exceptionally high. 6Li and 7Li NMR titration experiments also corroborated these results. These powerful NMR tools could be applied to the widespread studies of organometallic aggregates.

Physical Organic Chemistry, Combinatorial and Process Chemistry, New Reactions and Methodology, Peptides, Proteins and Amino Acids
8:00 PM-10:00 PM, Sunday, April 6, 2008 Morial Convention Center -- Hall A, Poster

Division of Organic Chemistry

The 235th ACS National Meeting, New Orleans, LA, April 6-10, 2008