title: Asymmetric dearomatization of the furan ring promoted by conjugate organolithium addition to (menthyloxy)(3-furyl)carbene complexes of chromium.
abstract: The sequential low-temperature addition reaction of an organolithium compound and methyl triflate to (menthyloxy)(3-furyl)carbene complexes of chromium and tungsten proceeded with excellent regioselectivity (1,4-addition) and diastereoselectivity (2,3-trans disposition of the nucleophile and electrophile groups) to afford new 2,3-disubstituted (2,3-dihydro-3-furyl)carbene complexes. In addition, a high degree of diastereofacial selectivity was achieved by employing alkenyllithium compounds. After detachment of both the metal fragment and the chiral auxiliary group, trisubstituted 2,3-dihydrofuran derivatives containing a quaternary stereogenic center at the C3 position were obtained. The characterization, including X-ray crystallography, of a novel type of stable four-membered chelate (eta(2)-alkene)tetracarbonylcarbene complex of chromium is also reported.
authors.affiliation: Instituto Universitario de Química Organometálica Enrique Moles, Unidad Asociada al CSIC, Universidad de Oviedo, Julián Clavería 8, 33006 Oviedo, Spain. barluenga@sauron.quimica.uniovi.es
authors.forename: José
authors.initials: J
authors.lastname: Barluenga
authors.forename: Sandip K
authors.initials: SK
authors.lastname: Nandy
authors.forename: Y R Santosh
authors.initials: YR
authors.lastname: Laxmi
authors.forename: José Ramón
authors.initials: JR
authors.lastname: Suárez
authors.forename: Isabel
authors.initials: I
authors.lastname: Merino
authors.forename: Josefa
authors.initials: J
authors.lastname: Flórez
authors.forename: Santiago
authors.initials: S
authors.lastname: García-Granda
authors.forename: José
authors.initials: J
authors.lastname: Montejo-Bernardo