title: Easy access to modified cyclodextrins by an intramolecular radical approach.
abstract: A simple method to modify the primary face of cyclodextrins (CDs) is described. The 6(I)-O-yl radical of α-, β-, and γ-CDs regioselectively abstracts the H5(II), located in the adjacent D-glucose unit, by an intramolecular 1,8-hydrogen-atom-transfer reaction through a geometrically restricted nine-membered transition state to give a stable 1,3,5-trioxocane ring. The reaction has been extended to the 1,4-diols of α- and β-CD to give the corresponding bis(trioxocane)s. The C2-symmetric bis(trioxocane) corresponding to the α-CD is a stable crystalline solid whose structure was confirmed by X-ray diffraction analysis. The calculated geometric parameters confirm that the primary face is severely distorted toward a narrower elliptical shape for this rim.
authors: Síntesis de Productos Naturales, Instituto de Productos Naturales y Agrobiología del CSIC, Carretera de la Esperanza 3, 38203, La Laguna, Tenerife (Spain).
authors: Dimitri
authors: D
authors: Alvarez-Dorta
authors: Elisa I
authors: EI
authors: León
authors: Alan R
authors: AR
authors: Kennedy
authors: Angeles
authors: A
authors: Martín
authors: Inés
authors: I
authors: Pérez-Martín
authors: Ernesto
authors: E
authors: Suárez
mesh_terms: D018360:Crystallography, X-Ray; D003505:Cyclodextrins / Q000737:chemistry*; D005947:Glucose / Q000737:chemistry; D006859:Hydrogen / Q000737:chemistry; D008968:Molecular Conformation; D013237:Stereoisomerism
chemical_list: D003505:Cyclodextrins; D006859:Hydrogen; D005947:Glucose
keywords: cyclodextrins; host-guest systems; hydrogen transfer; radical reactions; structure elucidation