Cyclization of Propargylic Amides: Mild Access to Oxazole Derivatives |
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Authors: | Jan P. Weyrauch Dr. A. Stephen K. Hashmi Prof. Dr. Andreas Schuster Dipl.‐Chem. Tobias Hengst Dipl.‐Chem. Stefanie Schetter Anna Littmann Dipl.‐Chem. Matthias Rudolph Dr. Melissa Hamzic Dr. Jorge Visus Jan W. Bats Dr. |
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Affiliation: | 1. Institut für Organische Chemie, Universit?t Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart (Germany);2. Organisch‐Chemisches Institut, Ruprecht‐Karls‐Universit?t Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg (Germany), Fax: (+49)?6221‐544205 |
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Abstract: | The substrate scope, the mechanistic aspects of the gold‐catalyzed oxazole synthesis, and substrates with different aliphatic, aromatic, and functional groups in the side chain were investigated. Even molecules with several propargyl amide groups could easily be converted, delivering di‐ and trioxazoles with interesting optical properties. Furthermore, the scope of the gold(I)‐catalyzed alkylidene synthesis was investigated. Further functionalizations of these isolable intermediates of the oxazole synthesis were developed and chelate ligands can be obtained. The use of Barluenga’s reagent offers a new and mild access to the synthetically valuable iodoalkylideneoxazoles from propargylic amides, this reagent being superior to other sources of halogens. |
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Keywords: | cyclization fluorescence gold catalysis methyleneoxazolines oxazoles propargylic amides |
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