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Updated: Jul 26, 2025

A Two-Step Protocol for Umpolung Functionalization of Ketones Via Enolonium Species
Published on: August 16, 2018
Electrophilic 1,4-Addition of Carbon Dioxide and Aldehydes to Enones
Shintaro Okumura1, Kaoru Torii1, Yasuhiro Uozumi1
1Institute for Molecular Science, Okazaki 444-8787, Japan.
Abstract:
An umpoled electrophilic 1,4-addition to enones was achieved under photocatalytic conditions. Various enones reacted with CO2 in the presence of an iridium photocatalyst and a benzimidazoline reductant under blue-light irradiation to give the corresponding γ-keto carboxylic acids. Aldehydes also coupled with enones under similar photocatalytic conditions to afford γ-keto alcohols (homoaldols) that were transformed into dihydrofurans and tetrahydrofurans through azeotropic posttreatments. Regioselective deuterium incorporation from D2O at the β-position demonstrated that 1,4-addition takes place via homoenolate anions.
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