A Photochemical Organocatalytic Strategy for the α-Alkylation of Ketones by using Radicals |
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Authors: | Davide Spinnato Dr Bertrand Schweitzer-Chaput Dr Giulio Goti Dr Maksim Ošeka Prof Dr Paolo Melchiorre |
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Institution: | ICIQ—Institute of Chemical Research of Catalonia the Barcelona Institute of Science and Technology, Avenida Països Catalans 16, 43007 Tarragona, Spain |
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Abstract: | Reported herein is a visible-light-mediated radical approach to the α-alkylation of ketones. This method exploits the ability of a nucleophilic organocatalyst to generate radicals upon SN2-based activation of alkyl halides and blue light irradiation. The resulting open-shell intermediates are then intercepted by weakly nucleophilic silyl enol ethers, which would be unable to directly attack the alkyl halides through a traditional two-electron path. The mild reaction conditions allowed functionalization of the α position of ketones with functional groups that are not compatible with classical anionic strategies. In addition, the redox-neutral nature of this process makes it compatible with a cinchona-based primary amine catalyst, which was used to develop a rare example of enantioselective organocatalytic radical α-alkylation of ketones. |
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Keywords: | α-Alkylierungen Enamine Photochemie Radikalchemie Silylenolate |
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