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Updated: Jun 2, 2026

Facile Preparation of (2Z,4E)-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate
Published on: June 21, 2017
Ruthenium-catalyzed (2 + 2) intramolecular cycloaddition of allenenes
Moisés Gulías1, Alba Collado, Beatriz Trillo
1Departamento de Química Orgánica y Centro Singular de Investigación en Química Biológica y Materiales Moleculares, Unidad Asociada al CSIC, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain.
Abstract:
We report a ruthenium-catalyzed (2 + 2) intramolecular cycloaddition of allenes and alkenes. We have found that the use of the ruthenium complex RuH(2)Cl(2)(P(i)Pr(3))(2), which has previously gone unnoticed in catalytic applications, is crucial for the observed reactivity. The reaction proceeds under mild conditions and is fully diastereoselective, providing a practical entry to a variety of bicyclo[3.2.0]heptane skeletons featuring cyclobutane rings.
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Cycloaddition Reactions: Overview
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[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
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.
Electrophilic Addition to Alkynes: Halogenation
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.

