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Updated: Jun 6, 2025

A Two-Step Protocol for Umpolung Functionalization of Ketones Via Enolonium Species
Published on: August 16, 2018
Redox-Neutral Umpolung Synthesis of α-Functionalized Amides
Rui Wang1, Shaokang An1, Yi-Xuan Xin2
1School of Chemistry, Sun Yat-sen University, Guangzhou 510006, P.R. China.
Abstract:
α-Heteroatom-substituted amides are useful as both targets and intermediates but are challenging to synthesize via conventional enolate chemistry. Herein, we describe a general and unified umpolung procedure to prepare α-heteroatom-functionalized secondary amides with various heteroatom-based nucleophiles under redox-neutral conditions. This transformation is a formal oxidation state reshuffle process from -N to -C in the hydroxamate, thereby achieving the umpolung α-heterofunctionalization of carbonyl groups without external oxidants. Regulated by the reshuffle mechanism, functionalization exclusively occurs at the α-position of the hydroxamate and precisely affords the α-functionalized amide with reliable predictability even in complex settings. Density functional theory studies support that soft enolization enabled by Mg2+/DIPEA combination is essential to facilitate the formation of the α-lactam intermediate. This represents the first general protocol to prepare α-functionalized secondary amides.
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