Related Experiment Video
Updated: Dec 10, 2025

Efficient Synthesis of All-Carbon Quaternary Centers via the Conjugate Addition of Functionalized Monoorganozinc Bromides
Published on: May 26, 2019
Zwitterion-Catalyzed Deacylative Dihalogenation of β-Oxo Amides
Zhihai Ke1, Ying-Pong Lam1, Kin-San Chan1
1Department of Chemistry and State Key Laboratory of Synthetic Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong.
Abstract:
α,α-Dihalo-N-arylacetamides are commonly used as intermediates in various organic reactions. In the study described here, a catalytic synthesis of α,α-dihalo-N-arylacetamides from β-oxo amides was developed using zwitterionic catalysts and N-halosuccinimides as the halogen sources. The corresponding α,α-dihalo-N-arylacetamides were obtained in good to excellent yields, and no aromatic halogenated side products were detected. The reaction conditions were mild, and no strong base or acid was required.
More Related Videos
Related Concept Videos
Acid-Catalyzed α-Halogenation of Aldehydes and Ketones
In the first step of the mechanism, the acid protonates the carbonyl oxygen resulting in a resonance-stabilized cation, which subsequently loses an α-hydrogen to form an enol tautomer. The C=C bond in an enol is highly nucleophilic because of the electron-donating nature of the –OH group. Consequently, the double bond attacks an electrophilic halogen to form a...
Base-Promoted α-Halogenation of Aldehydes and Ketones
Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide
Oxidation of Alkenes: Anti Dihydroxylation with Peroxy Acids
Preparation of Alkynes: Dehydrohalogenation
Alkynes can be prepared by dehydrohalogenation of vicinal or geminal dihalides in the presence of a strong base like sodium amide in liquid ammonia. The reaction proceeds with the loss of two equivalents of hydrogen halide (HX) via two successive E2 elimination reactions.
Halogenation of Alkenes
Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate.

