ORGN 310 |
| 2,2'-Bipyrroles are key synthetic precursors for porphycenes, corroles, saphyrins and other expanded porphyrin analogs. Most of the current bipyrrole syntheses are mainly based on an Ullmann dimerization reaction of a preformed pyrrole or on oxidative coupling. However, the Ullmann reaction for bipyrrole synthesis generally requires high temperatures and thus few functional groups can survive the conditions. Moreover, the type of bipyrroles accessible from the Ullmann reaction and from oxidative coupling is very limited and many bipyrroles are still inaccessible or can only be obtained in low yields. Although some improvements have recently been made to bipyrrole synthesis, tedious synthetic routes are still involved and yields are low. We have developed an efficient novel synthetic route to synthesize bipyrroles and eventually porphycenes based on a Pd(0)-catalyzed reaction. In this novel synthetic route, the reaction can be performed at room temperature under very mild reaction condition and provides good yields of bipyrroles in most cases. The synthesis of a series of bipyrroles using this novel synthetic route will be presented and the scope and limitations of the reaction will be discussed. Further usage of the bipyrroles in synthesis of porphycenes will also be reported. |
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Heterocycles and Aromatics
8:00 AM-12:00 PM, Tuesday, March 27, 2007 McCormick Place Lakeside -- Room E350, Level 3, Oral
Division of Organic Chemistry |