title: Ruthenium-catalyzed synthesis of functional conjugated dienes via addition of two carbene units to alkynes.
abstract: The reaction of a variety of alkynes with N(2)CHSiMe(3), in the presence of Cp*RuCl(cod) as the catalyst precursor, leads to the general formation of functional conjugated dienes. This selective formation results from the ruthenium-catalyzed creation of two carbon-carbon double bonds in a single step under mild conditions. Terminal alkynes produce 1,4-bistrimethylsilylbuta-1,3-dienes with Z stereoselectivity for the less hindered double bond whereas disubstituted alkynes favor E-configuration for the same double bond. Diynes react also as monoalkynes, and only one triple bond is transformed to give disilylated dienynes. The reaction can be applied to the in situ desilylation in methanol and formation of monosilylated dienes. The catalytic formation of 1,4-bisfunctional buta-1,3-dienes can also take place with N(2)CHCO(2)Et and N(2)CHPh. The reaction can be understood by addition of two carbene units to triple bonds. An initial [2 + 2] addition of the Ru=CHSiMe(3) bond with the alkyne triple bond leads to an alkenyl ruthenium-carbene species capable of coordinating a second carbene unit to produce conjugated dienes.
authors.affiliation: Laboratoire Catalyse et Organométalliques, UMR 6226-Sciences Chimiques de Rennes, CNRS-Université de Rennes 1, Campus de Beaulieu, 35042 Rennes, France.
authors.forename: Jacques
authors.initials: J
authors.lastname: Le Paih
authors.forename: Chloé
authors.initials: C
authors.lastname: Vovard-Le Bray
authors.forename: Sylvie
authors.initials: S
authors.lastname: Dérien
authors.forename: Pierre H
authors.initials: PH
authors.lastname: Dixneuf
mesh_terms: D000466:Alkadienes / Q000737:chemistry*; D000480:Alkynes / Q000737:chemistry*; D002384:Catalysis; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry; D017975:Ruthenium Compounds / Q000737:chemistry*; D017655:Silicon Compounds / Q000737:chemistry*
chemical_list: D000466:Alkadienes; D000480:Alkynes; D017975:Ruthenium Compounds; D017655:Silicon Compounds; C439868:1,5-cyclooctadiene; C030011:carbene; D008697:Methane; C038365:ruthenium chloride