title: Asymmetric hydroxylative phenol dearomatization promoted by chiral binaphthylic and biphenylic iodanes.
abstract: The long-standing quest for chiral hypervalent organoiodine compounds (i.e., iodanes) as metal-free reagents for asymmetric synthesis continues. Although remarkable progress has recently been made in organoiodine-catalyzed reactions using a terminal oxidant in stoichiometric amounts, there is still a significant need for "flaskable" chiral iodane reagents. Herein, we describe the synthesis of new iodobinaphthyls and iodobiphenyls, their successful and selective DMDO-mediated oxidation into either λ(3)- or λ(5)-iodanes, and the evaluation of their capacity to promote asymmetric hydroxylative phenol dearomatization (HPD) reactions. Most notably, a C2-symmetrical biphenylic λ(5)-iodane promoted the HPD-induced conversion of the monoterpene thymol into the corresponding ortho-quinol-based [4+2] cyclodimer (i.e., bis(thymol)) with enantiomeric excesses of up to 94%.
authors.affiliation: Univ. Bordeaux, ISM (CNRS-UMR 5255) and IECB, 2 rue Robert Escarpit, 33607 Pessac Cedex (France).
authors.forename: Cyril
authors.initials: C
authors.lastname: Bosset
authors.forename: Romain
authors.initials: R
authors.lastname: Coffinier
authors.forename: Philippe A
authors.initials: PA
authors.lastname: Peixoto
authors.forename: Mourad
authors.initials: M
authors.lastname: El Assal
authors.forename: Karinne
authors.initials: K
authors.lastname: Miqueu
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Sotiropoulos
authors.forename: Laurent
authors.initials: L
authors.lastname: Pouységu
authors.forename: Stéphane
authors.initials: S
authors.lastname: Quideau
keywords: asymmetric synthesis; dearomatization; hypervalent compounds; iodanes; natural products