ORGN 589 |
| Radical cyclization of bromoacetates and brominated acrylates in the presence of tributyltin hydride and AIBN yields predominantly an open hydrogen terminated chain product and a small amount of lactone. This is primarily due to the low reactivity of the generated polar radicals with the nonpolar C=C double bond in the case of bromoacetates and vice versa for brominated acrylates. Copper(I) homoscorpionate complexes with electron donating and withdrawing groups were utilized in free radical cyclization of bromoacetates and brominated acrylates with the aim of investigating the effect of C=C double bond coordination to the copper (I) center on the yield and selectivity of the cyclization reaction. The presence of a copper (I) complex in the reaction system increased the percent conversion of bromoacetates and brominated acrylates. Radical cyclization of bromoacetates in the presence of copper (I) complexes with electron-donating pyrazole ligands showed a three-fold increase in the percent yield of lactones. On the other hand, copper (I) complexes with electron-withdrawing pyrazole ligands favored the formation of lactones for brominated acrylates. |
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Metal-Mediated Reactions and Syntheses
1:00 PM-4:20 PM, Wednesday, March 28, 2007 McCormick Place Lakeside -- Room E350, Level 3, Oral
Division of Organic Chemistry |