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International audience; The first example of a ruthenium-catalyzed C–H bond alkylation via six-membered ruthenacycles is presented. This is disclosed for the C–H bond alkylation of biologically relevant cyclic amides with maleimide derivatives. The cyclic tertiary amide core acted as a directing group (DG) enabling formation of six-membered cycloruthenated species responsible for the control of the regio- and site selectivity of the reaction as well as the excellent functional group tolerance. Unexpectedly, cyclic amides were found to be better DGs than pyridine-containing ones or cyclic imides for this type of C–H bond functionalization.

The synthesis and characterization of new dicationic ruthenium and iridium complexes bearing a dipyridylamine ligand (dpa) are reported. These complexes display an unusual zwitterionic molecular structure in the solid state. The iridium complex [Cp*Ir(dpa)(OSO3)] (Ir1) was found to be very efficient in base-free hydrogenation of levulinic acid into γ-valerolactone (GVL). TONs as high as 174000 in hydrogenation have been obtained. We have demonstrated that reduction of LA into GVL by transfer hydrogenation with formic acid is in fact operating by hydrogenation fed by preliminary formic acid dehydrogenation. A mechanism based on the characterization and isolation of Ir–H complexes is proposed.

A single step synthetic strategy for (±)10- Desbromoarborescidine A is described. Starting from tryptamine and pentan-1,5-diol, this acceptorless dehydrogenative condensation process is efficiently catalyzed by a ruthenium complex featuring proton-responsive phosphine pyridone ligand.Manuscript is available supporting material is available and includes experimental procedures, characterization of compounds, 1H, 13C NMR spectra and chromatograms.

International audience; The selective and efficient transfer hydrogenation of levulinic acid into γ-valerolactone was performed with new ruthenium and iridium catalysts bearing dipyridylamine (dpa) ligands. Reactions were performed in the presence of formic acid and triethylamine using catalyst loading as low as 0.05 mol % with a ruthenium complex (turnover number = 1980). Recyclability of a ruthenium catalyst was demonstrated by running 6 consecutive reactions in almost quantitative yields.

ACHARD, Mathieu/0000-0003-0578-9680; bruneau, christian/0000-0002-2220-1458; Sahin, Onur/0000-0003-3765-3235 WOS: 000356841800031 A series of new benzimidazolium salts and ruthenium(II) complexes containing chelating N-heterocyclic carbenes (NHCs) functionalized with a benzylic group and an acetal group were prepared. All of the synthesized compounds were characterized by elemental analysis and NMR spectroscopy, and the molecular structures of 2c and 2d were determined by X-ray crystallography. All of the,complexes were tested in the alkylation of cyclic amine derivatives with alcohols and showed excellent activity in this reaction. Cyclic amines were alkylated with primary and heteroaromatic alcohols. The Ru-NHC Complexes also catalyzed N,C3-dialkylation of cyclic amines. Technological and Scientific Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [112T303]; Inonu University Research FundInonu University [I.U. B.A.P: 2014/Gudumlu-53] This work was financially supported by the Technological and Scientific Research Council of Turkey (TUBITAK) (112T303) and the Inonu University Research Fund (I.U. B.A.P: 2014/Gudumlu-53).

The synthesis of new fluorinated ruthenium(II) carbene second-generation precatalysts with unsymmetrical N-heterocyclic carbene ligands has been developed. The reaction profiles of these complexes have been studied in RCM with model substrates such as diethyl diallyl- and allylmethallyl-malonate, and CM model reaction of allylbenzene with 1,4-diacetoxybut-2-ene. In olefin metathesis reactions, the new fluorinated second-generation Grubbs complexes exhibit comparable activity with respect to commercially available Grubbs catalysts. On the other hand, in RCM reactions, the Hoveyda-type catalysts present a latent character, which is not present in the classical second-generation Hoveyda catalyst.

International audience; The higher reactivity of C5-H bonds of heteroarenes as compared to C-H bonds of bromopolyfluorobenzenes for palladium-catalyzed direct arylation allows the selective synthesis of the polyfluoroaryl-heteroarenes in moderate to high yields, without C-H bond functionalization of the polyfluorobenzene ring. In most cases, low loading of Pd(OAc)2 catalyst (0.5-1 mol %) was employed. Then, from these heteroarylated polyfluorobenzenes, the palladium-catalyzed C-H bond functionalization of the polyfluorobenzene ring allows the synthesis of heteroarylated polyfluorobiphenyls.

The reaction of SnCl2 with the Ru−Cl bond of the Grubbs I catalyst RuCl2(═CHPh)(PCy3)2 (1) gives the complex {[Ru(═CHPh)(SnCl3)(PCy3)]2(μ-Cl)3}−[HPCy3]+ (2), but containing two diethyl ether solvate molecules. The formal insertion of SnCl2 into one Ru−Cl bond of the Hoveyda II catalyst RuCl2(═CH-C6H4OPri)(H2IMes) (3) (H2IMes = N,N′-dimesityl-4,5-dihydroimidazol-2-ylidene) results in formation of the new complex RuCl(SnCl3)(═CH-C6H4OPri)(H2IMes) (4). The X-ray analyses of 2 and 4 show the presence of very short Ru−Sn bonds (2.5834(9) A mean bond for 2 and 2.5925(12) A for 4) and the retention of short Ru═C bonds (1.895(10) and 1.825(8) A, respectively). Complex 4 shows an excellent catalytic activity for the cross-metathesis of plant oil derivatives, the C11 ω-unsaturated ester and aldehyde and the unsaturated C18 diester with acrylonitrile, and a good activity for their cross-metathesis with methyl acrylate. Good to excellent yield of α,ω-bifunctional compounds, precursors of polyesters and polyamides, we...

The ring-closing metathesis reaction of N,N-diallyltosylamide (2) catalyzed by [(η6-p-cymene)(PCy3)RuCl(CCCPh2)]X (X = OTf (CF3SO3) (1), PF6, BF4, SbF6) and by [(η6-p-cymene)(PCy3)RuCl(CCC(p-Y-C6H4)2]OTf (Y = MeO, Cl, F) complexes has been monitored in situ by 1H NMR, in benzene-d6 and in dichloromethane-d2, in the temperature range 33−58 °C. The reaction proceeds selectively to form N-tosyl-2,5-dihydropyrrole (3), in the case of complexes [(η6-p-cymene)(PCy3)RuCl(CCCPh2)]X (X = OTf, PF6), under thermal activation, while lower reactivity and selectivity are exhibited by the other complexes. Evidence is given for an activation step leading to the catalytic species. Under pseudo-first-order conditions, the metathesis reaction catalyzed by complex 1 is first-order in the diallylic substrate in benzene-d6 above 50 °C when the propagation step is slower than the activation of the catalytic species. The reaction is zero-order in substrate at lower temperatures when the activation of the ruthenium complex is slo...

Regioselective formation of 2-(benzoyloxy)propene results from the addition of benzoic acid to propyne in the presence of the trigonal-bipyramidal Rh(I) monohydrides [(PPh 3 )RhH] (1) and [(NP 3 )RhH] (2, PP 3 =P(CH 2 CH 2 PPh 2 ) 3 , NP 3 =N(CH 2 CH 2 PPh 2 ) 3 ). The reactions are catalytic under relatively mild conditions (catalyst to substrate ratio 1:100, toluene, 100 o C). A detailed experimental study on the reactions of 1 and 2 with carboxylic acids, 1-alkynes, or carboxylic acid/1-alkyne mixtures has allowed us to draw a catalysis cycle involving the 16-electron fragments [(L)Rh] + as catalysts (L=PP 3 , NP 3 ). The catalytic behavior of the precursors 1 and 2 has been compared and contrasted with those of the isostructural and isoelectronic derivatives [(L)Rh(C≡CPh), [(L)RhCl], and [(PP 3 )RhMe]. The novel vinylphosphonium complex [(Ph 2 PCH 2 CH 2 ) 2 P(CH 2 CH 2 PPh 2 )Rh{C=C(H)Ph}(O 2 CPh) has been synthesized and fully characterized by IR and 1 H and 34 P{ 1 H} NMR techniques

The enantioselective hydrogenation of α-methylene-1,3-dioxolan-2-ones catalyzed by chiral (diphosphine)ruthenium complexes leads to optically active cyclic carbonates with high enantioselectivities. Their hydrolysis in methanol in the presence of potassium carbonate quantitatively affords optically active 1,2-diols.

Aliphatic and araliphatic primary amines react with carbon dioxide at 120-140°C in the presence of ruthenium complexes and terminal alkynes, especially propargyl alcohols, to directly afford N,N'-disubstituted symmetrical ureas. The alkyne ruthenium intermediate acts as a dehydrating reagent. This new and mild method avoids the classical use of carbonyl precursors like phosgene or isocyanates

Direct functionalization of sp2 C−H bonds via ortho diarylation of 2-pyridyl benzene with arylbromides was achieved using ruthenium(II) catalysts containing a RuCl2(NHC) unit and generated from [RuCl2(arene)]2 and two types of NHC precursors, pyrimidinium and benzimidazolium salts, in the presence of Cs2CO3. DFT calculations from RuCl2(NHC)(2-pyridylbenzene) show that a proton abstraction mechanism, on cooperative actions of both the coordinated base and the Ru(II) center, is favored via a 13.7 kcal·mol-1 exothermic process affording an orthometalated intermediate with a 2.009 A Ru−C bond.