title: Tandem beta-boration/arylation of alpha,beta-unsaturated carbonyl compounds by using a single palladium complex to catalyse both steps.
abstract: Diphenyl(3-methyl-2-indolyl)phosphine (C(9)H(8)NPPh(2), 1) gives stable dimeric palladium(II) complexes that contain the phosphine in P,N-bridging coordination mode. On treating 1 with [Pd(O(2)CCH(3))(2)], the new complexes [Pd(mu-C(9)H(7)NPPh(2))(NCCH(3))](2) (2) or [Pd(mu-C(9)H(7)NPPh(2))(mu-O(2)CCH(3))](2) (3) were isolated, depending on the solvent used, acetonitrile or toluene, respectively. Further reaction of 3 with the ammonium salt of 1 led to the substitution of one carboxylate ligand to afford [Pd(mu-C(9)H(7)NPPh(2))(3)(mu-O(2)CCH(3))] (4), in which the bimetallic unit is bonded by three C(9)H(7)NPPh(2)(-) moieties and one carboxylate group. Using this methodology, [Pd(2)(mu-C(6)H(4)PPh(2))(2)(mu-C(9)H(7)NPPh(2))(mu-O(2)CCX(3))] (X=H (7); X=F (8)) were synthesised from the ortho-metalated compounds [Pd(C(6)H(4)PPh(2))(mu-O(2)CCX(3))](2) (X=H (5); X=F (6)). Complexes 3, 4, 7, and 8 have been found to be active in the catalytic beta-boration of alpha,beta-unsaturated esters and ketones under mild reaction conditions. Hindrance of the carbonyl moiety has an influence on the reaction rate, but quantitative conversion was achieved in many cases. More remarkably, when aryl bromides were added to the reaction media, complex 7 induced a highly successful consecutive beta-boration/cross-coupling reaction with dimethyl acrylamide as the substrate (99% conversion, 89% isolated yield).
authors.affiliation: Departament de Química Física i Inorgànica, Universitat Rovira i Virgili, C/Marcel.lí, Domingo s/n, 43007 Tarragona, Spain.
authors.forename: Amadeu
authors.initials: A
authors.lastname: Bonet
authors.forename: Henrik
authors.initials: H
authors.lastname: Gulyás
authors.forename: Igor O
authors.initials: IO
authors.lastname: Koshevoy
authors.forename: Francisco
authors.initials: F
authors.lastname: Estevan
authors.forename: Mercedes
authors.initials: M
authors.lastname: Sanaú
authors.forename: M Angeles
authors.initials: MA
authors.lastname: Ubeda
authors.forename: Elena
authors.initials: E
authors.lastname: Fernández