Related Experiment Video
Updated: Apr 5, 2026

Facile Preparation of 2Z,4E-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate
Published on: June 21, 2017
Reversible 1,2-Alkyl Migration to Carbene and Ammonia Activation in an N-Heterocyclic Carbene-Zirconium Complex
Emmanuelle Despagnet-Ayoub1, Michael K Takase1, Jay A Labinger1
1Arnold and Mabel Beckman Laboratories of Chemical Synthesis, California Institute of Technology , Pasadena, California 91125, United States.
Abstract:
Addition of trimethylphosphine to a bis(phenolate)benzylimidazolylidene(dibenzyl)zirconium complex induces migration of a benzyl ligand from the metal center to the C(carbine) atom. This process may be reversed, resulting in Csp(3)-Csp(3) activation, by abstraction of the phosphine, an example of regulated, reversible alkyl migration. Addition of ammonia to the dibenzyl complex results in migration of one benzyl group and protonolysis of the other to generate a bis(NH2)-bridged dimer via an NMR-observable intermediate NH3 adduct.
Related Concept Videos
Preparation of 1° Amines: Hofmann and Curtius Rearrangement Mechanism
Amines to Alkenes: Hofmann Elimination
Under thermal conditions, the hydroxide can abstract a proton from the β carbon; this generates an alkene with the simultaneous...
Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration
Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
Preparation of 1° Amines: Hofmann and Curtius Rearrangement Overview

