title: Stereocontrol in rare earth metal triflate-catalyzed 1,3-dipolar cycloaddition reaction of 2-benzopyrylium-4-olate with aldehydes
abstract: Exo-cycloadduct was obtained with high stereoselectivity by the addition of ytterbium triflate (Yb(OTf)(3)) (10 mol %) in the rhodium(II) acetate (Rh(2)(OAc)(4))-catalyzed decomposition of o-(methoxycarbonyl)-alpha-diazoacetophenone in the presence of benzaldehyde. In the reaction in the absence of Yb(OTf)(3), almost no selectivity was obtained. Stereoselectivity in the reactions with p-nitrobenzaldehyde, p-anisaldehyde, and benzyloxyacetaldehyde could be also controlled to high exo preference by the addition of Yb(OTf)(3).
authors.affiliation: Department of Chemistry and Material Engineering, Faculty of Engineering, Shinshu University, Wakasato, Nagano 380-8553, Japan, and Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
authors.initials: H
authors.lastname: Suga
authors.initials: A
authors.lastname: Kakehi
authors.initials: S
authors.lastname: Ito
authors.initials: K
authors.lastname: Inoue
authors.initials: H
authors.lastname: Ishida
authors.initials: T
authors.lastname: Ibata