Related Experiment Video
Updated: Jul 7, 2026

A Two-Step Protocol for Umpolung Functionalization of Ketones Via Enolonium Species
Published on: August 16, 2018
Diastereoselective cyclopropanation of ketone enols with Fischer carbene complexes
José Barluenga1, Marcos G Suero, Ivan Pérez-Sanchez
1Instituto Universitario de Química Organometálica "Enrique Moles" Unidad Asociada al CSIC, Universidad de Oviedo Julián Clavería 8, 33006 Oviedo, Spain. barluenga@uniovi.es
Abstract:
Treatment of aryl/heteroaryl methoxycarbene complexes of chromium with -substituted ketone lithium enolates between -78 degrees C and room temperature resulted in the diastereoselective synthesis of 1,2,2,3-tetrasubstituted cyclopropanols. An exception has been observed in the reaction with cyclohexanone lithium enolate that yielded a bicyclic 2-buten-4-olide. 1,2-Dimethoxycyclopropanes and 1-methoxy-2-trimethylsilyloxycyclopropanes were isolated by quenching the reactions with MeOTf or Me3SiCl, respectively. This novel cyclopropanation process involves formation of lithium (3-oxoalkyl)pentacarbonylchromate intermediates which on warming undergo intramolecular addition to the carbonyl group. This cyclization is equivalent to the cyclopropanation in smooth conditions of electron-rich alkenes with Fischer carbene complexes.
More Related Videos
Related Concept Videos
Types of Enols and Enolates
α-Alkylation of Ketones via Enolate Ions
Stereochemical Effects of Enolization
Reactivity of Enols
Intramolecular Claisen Condensation of Dicarboxylic Esters: Dieckmann Cyclization
Alkylation of β-Ketoester Enolates: Acetoacetic Ester Synthesis

