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Updated: Dec 18, 2025

A Two-Step Protocol for Umpolung Functionalization of Ketones Via Enolonium Species
Published on: August 16, 2018
Generation and Reactivity of C(1)-Ammonium Enolates by Using Isothiourea Catalysis
Calum McLaughlin1, Andrew D Smith1
1EaStCHEM, School of Chemistry, University of St Andrews, North Haugh, Fife, KY16 9ST, Scotland.
Abstract:
C(1)-Ammonium enolates are powerful, catalytically generated synthetic intermediates applied in the enantioselective α-functionalisation of carboxylic acid derivatives. This minireview describes the recent developments in the generation and application of C(1)-ammonium enolates from various precursors (carboxylic acids, anhydrides, acyl imidazoles, aryl esters, α-diazoketones, alkyl halides) using isothiourea Lewis base organocatalysts. Their synthetic utility in intra- and intermolecular enantioselective C-C and C-X bond forming processes on reaction with various electrophiles will be showcased utilising two distinct catalyst turnover approaches.
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