ORGN 150 |
| Palladium-catalyzed annulative tandem/domino reactions of 1,2-dihaloarenes and 2-haloaryl tosylates with hindered Grignard Reagents to form substituted fluorenes by controlling the reaction pathways are described. Two palladium catalyst systems, Pd0/t-Bu3P and Pd(OAc)2, were employed. The Pd(0)/t-Bu3P-catalyzed annulative tandem reactions is believed to occur through cross-coupling followed by cyclization via sp3 C-H bond activation and the Pd(OAc)2-catalyzed annulative domino reactions is believed to involve palladium-associated arynes as reaction intermediates. Our study not only provided an efficient, one-step access to potentially useful substituted fluorenes from readily available 1-chloro-2-halobenzenes and 2-haloaryl tosylates, but may also lead to the development of other tandem/domino reactions based on the concepts of controlling reaction pathways by varying size of the substrates/reagents, the use of ligands and the reaction temperatures. |
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Process R&D, Physical Organic Chemistry, Heterocycles, Aromatics, Metal-Mediated Reactions
8:00 PM-10:00 PM, Sunday, March 25, 2007 Hyatt Regency Chicago -- Riverside Center, Poster
Division of Organic Chemistry |