title: Formation of a cyclobutylidene ring: intramolecular [2 + 2] cycloaddition of allyl and vinylidene C=C bonds under mild conditions.
abstract: Intramolecular [2 + 2] cycloaddition of two C=C bonds in vinylidene complexes [Ru(eta5-C9H7){=C=C(R)H}(PPh3){kappa1-(P)-PPh2(C3H5)][BF4] affords cyclobutylidene complexes [Ru(eta5-C9H7){kappa2-(P,C)-(=CC(R)HCH2CHCH2PPh2)}(PPh3)][BF4], which can be also obtained by reaction of terminal alkynes with [Ru(eta5-C9H7)(PPh3){kappa3-(P,C,C)-PPh2(C3H5)}][PF6]. The reaction proceeds under mild conditions via vinylidene complexes, and the activation parameters were determined by kinetic studies.
authors.affiliation: Departamento de Química Orgánica e Inorgánica, Instituto de Química Organometálica Enrique Moles (Unidad Asociada al C.S.I.C.), Facultad de Química, Universidad de Oviedo, 33006 Oviedo, Spain.
authors.forename: Patricia
authors.initials: P
authors.lastname: Alvarez
authors.forename: Elena
authors.initials: E
authors.lastname: Lastra
authors.forename: José
authors.initials: J
authors.lastname: Gimeno
authors.forename: Mauro
authors.initials: M
authors.lastname: Bassetti
authors.forename: Larry R
authors.initials: LR
authors.lastname: Falvello