Gold catalysis: phenol synthesis in the presence of functional groups |
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Authors: | Hashmi A Stephen K Weyrauch Jan P Kurpejović Elzen Frost Tanja M Miehlich Burkhard Frey Wolfgang Bats Jan W |
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Institution: | Institut für Organische Chemie, Universit?t Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany. hashmi@hashmi.de |
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Abstract: | The effect of different substituents, such as bromo, chloromethyl, hydroxymethyl, formyl, acetyl, carboxy, and acylated hydroxymethyl and ammonium groups, on the furan ring of substrates in gold-catalyzed phenol synthesis has been investigated. The furan ring was also replaced by different heterocycles, such as pyrroles, thiophenes, oxazoles, and a 2,4-dimethoxyphenyl group; gold catalysis then delivered no phenols, but occasionally other products were obtained. Ru(3)(CO)(12)] also catalyzed the conversion of 1 at a low rate, Os(3)(CO)(12)] failed as a catalyst, and with Co(2)(CO)(8)] the alkyne complex 19 can be obtained, it does not lead to any phenol but reacts with norbornene to give the product of a Pauson-Khand reaction. Efforts to prepare vinylidene complexes of 1 provided the only evidence for these species; in the presence of a phosphane ligand with ruthenium an interesting deoxygenation to 22 was observed. The phenol 2 c was converted to the allyl ether, a building block for para-Claisen rearrangements, and to the aryl triflate, a building block for cross-coupling reactions. |
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Keywords: | arenes gold homogeneous catalysis Pauson–Khand reaction ruthenium |
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