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Updated: Oct 8, 2025

A Two-Step Protocol for Umpolung Functionalization of Ketones Via Enolonium Species
Published on: August 16, 2018
Visible Light-Induced Reductive Alkynylation of Aldehydes by Umpolung Approach
Ibuki Tanaka1, Masaya Sawamura2,1, Yohei Shimizu2,1
1Department of Chemistry, Faculty of Science, Hokkaido University, Kita 10 Nishi 8, Kita-ku, Sapporo, Hokkaido 060-0810, Japan.
Abstract:
Reductive alkynylation of aldehydes by the Umpolung approach was developed using a photoredox catalyst under blue LED irradiation. Ketyl radicals, generated by single-electron reduction of aldehydes through proton-coupled electron transfer (PCET), reacted with electrophilic alkynylsulfones. Sterically demanding bulky aldehydes reacted smoothly under the Umpolung reaction conditions. Moreover, the alkynylation proceeded chemoselectively with an aryl aldehyde group in the presence of other carbonyl groups including an aliphatic aldehyde group.
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