ORGN 121 |
| Recently, we reported a study on the cleavage of trans- and cis-2-methyl-3,4-epoxy alcohols with diethylpropynylalane, were we found that two products, the 1,3-diol and the undesired 1,4-diol were obtained with varying degree of regioselectivity. In order to explain these results, we are proposing distinctive aluminum-oxygen chelation patterns: the bidentate pathway, were the aluminum reagent coordinates to the alkoxide and oxirane forming a cyclic chelate, and the monodentate pathway were two equivalents of the aluminum reagent interact separately. To corroborate this and to find a solution to the regioselectivity problem, we explored the use of MEM as a protecting group that would modify the aluminum coordination pattern. Ab-initio 27Al and 13C NMR calculations were performed and compared to the experimental data to better understand the regioselectivity of the reaction. Close correlation was observed for the NMR shifts for several systems.
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Asymmetric Reactions and Syntheses, Physical Organic Chemistry, Combinatorial Chemistry, Total Synthesis
8:00 PM-10:00 PM, Sunday, 26 March 2006 Georgia World Congress Center -- Ex. Hall B4, Poster
Sci-Mix
Division of Organic Chemistry |