title: A stepwise retro-imino-ene as a key step in the mechanism of allene formation via the Crabbé acetylene homologation.
abstract: The mechanism of the acetylene homologation procedure accidentally discovered and further developed by Crabbé and coworkers is unknown. Kinetic isotope effect (KIE) experiments, however, suggest that an intramolecular hydrogen shift is the key step of the transformation. In this work, we present a computational study of this mechanism. We found that the reaction proceeds via an unexpected stepwise retro-imino-ene rearrangement. This mechanism justifies the role of Cu(I) as a reaction catalyst and is also compatible with the KIE experiments reported.
authors.affiliation: Departamento de Química Orgánica, Facultade de Química, Universidade de Vigo, Lagoas, Marcosende, Vigo 36310, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: González
authors.forename: Roi Álvarez
authors.initials: RÁ
authors.lastname: Rodríguez
authors.forename: Maria Magdalena
authors.initials: MM
authors.lastname: Cid
authors.forename: Carlos Silva
authors.initials: CS
authors.lastname: López
mesh_terms: D000114:Acetylene / Q000737:chemistry*; D000466:Alkadienes / Q000138:chemical synthesis / Q000737:chemistry*; D002384:Catalysis; D003300:Copper / Q000737:chemistry; D007700:Kinetics
chemical_list: D000466:Alkadienes; C025947:propadiene; D003300:Copper; D000114:Acetylene