Related Experiment Video
Updated: Jun 20, 2026

Facile Preparation of (2Z,4E)-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate
Published on: June 21, 2017
Rhodium-mediated enantioselective cyclopropanation of allenes
Timothy M Gregg1, Mark K Farrugia, John R Frost
1Department of Chemistry and Biochemistry, Canisius College, Buffalo, New York 14208, USA. greggt@canisius.edu
Abstract:
Reaction of monosubstituted allenes with aryldiazoacetate esters under dirhodium tetracarboxylate catalysis led to alkylidene cyclopropane products in 80-90% ee. Monosubstituted alkyl- and arylallene substrates gave 60-75% yield under standard conditions, while yields for 1,1-disubstituted allenes were significantly lower. Cyclopropanation of 1-methyl-1-(trimethylsilyl)allene proceeded in higher yield than other 1,1-disubstituted substrates, suggesting rate enhancement mediated by a significant beta-silicon effect.
More Related Videos
Related Concept Videos
Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
Cyclohexenones via Michael Addition and Aldol Condensation: The Robinson Annulation
Radical Anti-Markovnikov Addition to Alkenes: Overview
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...
Regioselectivity of Electrophilic Additions-Peroxide Effect
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.

