title: Ligandless Palladium-Catalyzed Regioselective Direct C-H Arylation of Imidazo[1,2-a]imidazole Derivatives.
abstract: Herein a novel access to functionalizable 6-substituted imidazo[1,2-a]imidazole scaffolds is described. The reactivity of this heterobicyclic unit toward direct C-H arylation was studied, and conditions allowing regioselective arylation at position 3 were successfully developed. The practicability of this method is manifested by the ligandless conditions and low catalyst loading. The strategy is functional group tolerant and provides rapid access to a large variety of 3,6-di(hetero)arylated imidazo[1,2-a]imidazole derivatives. A second arylation at position 2 was then carried out, and a library of diversified 2,3,6-tri(hetero)arylated imidazo[1,2-a]imidazoles was generated in good yields. A one-pot, two-step procedure was finally developed.
authors.affiliation: Institut de Chimie Organique et Analytique (ICOA), Université d'Orléans, UMR-CNRS 7311 , BP 6759, rue de Chartres 45067 Orléans Cedex 2, France.
authors.forename: Sandrine
authors.initials: S
authors.lastname: Grosse
authors.affiliation: Greenpharma S.A.S. , 3, allée du Titane, 45100 Orléans, France.
authors.forename: Christelle
authors.initials: C
authors.lastname: Pillard
authors.affiliation: Université de Bordeaux , CNRS - UMS 3033, INSERM US001 -Institut Européen de Chimie et de Biologie -2 rue Robert Escarpit, 33607 Pessac, France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Massip
authors.affiliation: ICMCB UPR CNRS 9048, Université Bordeaux , 87 Av. Doc. A. Schweitzer, F-33608 Pessac Cedex, France.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Marchivie
authors.affiliation: Université de Bordeaux , CNRS - UMS 3033, INSERM US001 -Institut Européen de Chimie et de Biologie -2 rue Robert Escarpit, 33607 Pessac, France.
authors.forename: Christian
authors.initials: C
authors.lastname: Jarry
authors.affiliation: Greenpharma S.A.S. , 3, allée du Titane, 45100 Orléans, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Bernard
authors.affiliation: Institut de Chimie Organique et Analytique (ICOA), Université d'Orléans, UMR-CNRS 7311 , BP 6759, rue de Chartres 45067 Orléans Cedex 2, France.
authors.forename: Gérald
authors.initials: G
authors.lastname: Guillaumet