Related Experiment Video
Updated: May 23, 2026

A Protocol for Safe Lithiation Reactions Using Organolithium Reagents
Published on: November 12, 2016
Intramolecular vinylation of secondary and tertiary organolithiums
Julien Lefranc1, Anne M Fournier, Gaëlle Mingat
1School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
Abstract:
Deprotonation of benzylic ureas, carbamates, and thiocarbamates bearing N'-alkenyl substituents generates carbanions which undergo intramolecular migration of the alkenyl group to the carbanionic center. Solvolysis of the urea products generates α-alkenylated amines. With an enantiomerically pure starting urea, migration proceeds stereospecifically, generating in enantiomerically enriched form products containing allylic quaternary stereogenic centers bearing N. Computational and in situ IR studies suggest that the reaction, formally a nucleophilic substitution at an sp(2) carbon atom, proceeds by a concerted addition-elimination pathway.
More Related Videos
Related Concept Videos
Electrophilic Addition to Alkynes: Hydrohalogenation
Acid Halides to Alcohols: Grignard Reaction
Grignard reagents are a source of carbanions and function as nucleophiles. The mechanism begins with the nucleophilic attack by the carbanion at the carbonyl carbon of the acid halide to form a tetrahedral intermediate. Next, the carbonyl group is re-formed, and the halide ion departs,...
Preparation of Alkynes: Alkylation Reaction
Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne.
Preparation of Alcohols via Substitution Reactions
Alcohols can be synthesized from alkyl halides via nucleophilic substitution reactions. The highly polar carbon-halogen bond in the substrate makes halide a good leaving group. The hydroxide ion or water can act as a nucleophile to take the place of halide and form an alcohol. The substitution reactions occur via two different reaction pathways, SN1 or SN2, depending on the nature of carbon attached to the halide.
Primary alcohols are synthesized from primary alkyl halides, and the...
α-Alkylation of Ketones via Enolate Ions
Regioselectivity of Electrophilic Additions to Alkenes: Markovnikov's Rule
The hydrohalogenation of an unsymmetrical alkene can yield two haloalkane products, depending on which vinylic carbon takes up the halogen. However, one product usually predominates, where hydrogen adds to the vinylic carbon bearing the...

