An Expedient Method for the Umpolung Coupling of Enols with Heteronucleophiles** |
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Authors: | Víctor García-Vázquez Alba Carretero Cerdán Dr Amparo Sanz-Marco Prof Enrique Gómez-Bengoa Prof Belén Martín-Matute |
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Institution: | 1. Department of Organic Chemistry, Stockholm University, Stockholm, 10691 Sweden;2. Departamento de Química Orgánica I, Universidad Pais Vasco, UPV/EHU, 20080 Donostia-San Sebastián, Spain |
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Abstract: | In this paper, we present an unprecedented and general umpolung protocol that allows the functionalization of silyl enol ethers and of 1,3-dicarbonyl compounds with a large range of heteroatom nucleophiles, including carboxylic acids, alcohols, primary and secondary amines, azide, thiols, and also anionic carbamates derived from CO2. The scope of the reaction also extends to carbon-based nucleophiles. The reaction relies on the use of 1-bromo-3,3-dimethyl-1,3-dihydro-1λ3d]1,2]iodaoxole, which provides a key α-brominated carbonyl intermediate. The reaction mechanism has been studied experimentally and by DFT, and we propose formation of an unusual enolonium intermediate with a halogen-bonded bromide. |
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Keywords: | DFT enol derivatives hypervalent iodine(III) mechanistic insight umpolung |
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