title: Non-Innocent Behavior of Substrate Backbone Esters in Metal-Catalyzed Carbocyclizations and Friedel-Crafts Reactions of Enynes and Arenynes.
abstract: On the basis of DFT computations and experimental results, we show that the presence of the ester group in the backbone of organic substrates can influence the mechanism of metal-catalyzed carbocyclization reactions. The non-innocent role of the ester functionality in lowering the activation barrier of the key step of the gallium- and indium-catalyzed cycloisomerization of 1,6-enynes is revealed. In the case of the gallium-catalyzed hydroarylation of arenynes, the esters in the tether can deprotonate the Wheland intermediate, thus avoiding more energetically demanding [1,3]- or [1,2]/[1,2]-H shifts. As for the gallium-catalyzed Friedel-Crafts alkylation, an unusual concerted SEAr mechanism involving the esters has been calculated. Lastly, computations evidence that the ester group of methyl propiolates enables a divergent mechanism in the platinum-catalyzed intramolecular hydroarylation.
authors.affiliation: ICMMO (UMR CNRS 8182), Université Paris-Sud , Bâtiment 420, 91405 Orsay cedex, France.
authors.forename: Bastien
authors.initials: B
authors.lastname: Michelet
authors.affiliation: ICMMO (UMR CNRS 8182), Université Paris-Sud , Bâtiment 420, 91405 Orsay cedex, France.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Thiery
authors.affiliation: ICMMO (UMR CNRS 8182), Université Paris-Sud , Bâtiment 420, 91405 Orsay cedex, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Bour
authors.affiliation: ICMMO (UMR CNRS 8182), Université Paris-Sud , Bâtiment 420, 91405 Orsay cedex, France.|Institut de Chimie des Substances Naturelles, CNRS , Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Gandon