ORGN 480 |
| Chalcones (1,3-diaryl-2-propen-1-ones) are highly crystalline materials that can be readily prepared from crossed Aldol condensation of substituted benzaldehydes and acetophenones. As part of our program to prepare derivatives of chalcones, we needed to prepare the corresponding epoxides by reaction with hydrogen peroxide in presence of a base. In our studies, it was immediately apparent that depending on the substituents on either the A or B ring of the chalcone, the reaction proceeded in three general ways. They either produced the epoxide exclusively and in high chemical yields, or the chalcones reverted completely to the corresponding benzaldehydes and acetophenones in an apparent retro-Aldol reaction, or the chalcone reverted to the benzaldehyde and no acetophenone was detected. The reactivity of twenty different chalcones was studied under identical conditions of concentration, temperature, reaction time, and extraction procedures. The product mixtures were analyzed by NMR spectroscopy. The results from these studies as well as the effects of structure-electronic properties on reactivity will be presented. |
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New Reactions, Methodology, Total Synthesis, Physical Organic Chemistry
8:00 PM-10:00 PM, Tuesday, 15 March 2005 Convention Center -- Sails Pavilion, Poster
Division of Organic Chemistry |