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  • 1. Aaberg, Jenny B.
    et al.
    Samec, Joseph S. M.
    Baeckvall, Jan-E.
    Mechanistic investigation on the hydrogenation of imines by [p-(Me2CH)C6H4Me]RuH(NH2CHPhCHPhNSO2C6H4-p-CH3). Experimental support for an ionic pathway.2006In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, no 26, p. 2771-2773Article in journal (Refereed)
    Abstract [en]

    The need for acidic activation in the stoichiometric hydrogenation of benzyl-[1-phenyl-ethylidene]-amine (6a) or [1-(4-methoxy-phenyl)-ethylidene]-methyl-amine (6b) by Noyori's catalyst [p-(Me2CH)C6H4Me]RuH(NH2CHPhCHPhNSO2C6H4-p-CH3) (2) is inconsistent with the proposed concerted mechanism and supports an ionic mechanism. [on SciFinder(R)]

  • 2.
    Biswas, Srijit
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Dahlstrand, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Physical Organic Chemistry.
    Watile, Rahul A.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Kalek, Marcin
    Himo, Fahmi
    Samec, Joseph S. M.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Atom-Efficient Gold(I)-Chloride-Catalyzed Synthesis of alpha-Sulfenylated Carbonyl Compounds from Propargylic Alcohols and Aryl Thiols: Substrate Scope and Experimental and Theoretical Mechanistic Investigation2013In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 19, no 52, p. 17939-17950Article in journal (Refereed)
    Abstract [en]

    Gold(I)-chloride-catalyzed synthesis of -sulfenylated carbonyl compounds from propargylic alcohols and aryl thiols showed a wide substrate scope with respect to both propargylic alcohols and aryl thiols. Primary and secondary aromatic propargylic alcohols generated -sulfenylated aldehydes and ketones in 60-97% yield. Secondary aliphatic propargylic alcohols generated -sulfenylated ketones in yields of 47-71%. Different gold sources and ligand effects were studied, and it was shown that gold(I) chloride gave the highest product yields. Experimental and theoretical studies demonstrated that the reaction proceeds in two separate steps. A sulfenylated allylic alcohol, generated by initial regioselective attack of the aryl thiol on the triple bond of the propargylic alcohol, was isolated, evaluated, and found to be an intermediate in the reaction. Deuterium labeling experiments showed that the protons from the propargylic alcohol and aryl thiol were transferred to the 3-position, and that the hydride from the alcohol was transferred to the 2-position of the product. Density functional theory (DFT) calculations showed that the observed regioselectivity of the aryl thiol attack towards the 2-position of propargylic alcohol was determined by a low-energy, five-membered cyclic protodeauration transition state instead of the strained, four-membered cyclic transition state found for attack at the 3-position. Experimental data and DFT calculations supported that the second step of the reaction is initiated by protonation of the double bond of the sulfenylated allylic alcohol with a proton donor coordinated to gold(I) chloride. This in turn allows for a 1,2-hydride shift, generating the final product of the reaction.

  • 3.
    Biswas, Srijit
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Samec, Joseph
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    A Gold(I)-Catalyzed Route to α-Sulfenylated Carbonyl Compounds from Propargylic Alcohols and Aryl Thiols2012In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 48, no 52, p. 6586-6588Article in journal (Refereed)
    Abstract [en]

    A one-step atom efficient gold(I)-catalyzed route to α-sulfenylated ketones and aldehydes from propargylic alcohols and aryl thiols is described.

  • 4.
    Biswas, Srijit
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Samec, Joseph
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    The Efficiency of the Metal Catalysts in the Nucleophilic Substitution of Alcohols is Dependent on the Nucleophile and Not on the Electrophile2013In: Chemistry - An Asian Journal, ISSN 1861-4728, E-ISSN 1861-471X, Vol. 8, no 5, p. 974-981Article in journal (Refereed)
    Abstract [en]

    In this study, we investigate the effect of the electrophiles and the nucleophiles for eight catalysts in the catalytic SN1 type substitution of alcohols with different degree of activation by sulfur-, carbon-, oxygen-, and nitrogen-centered nucleophiles. The catalysts do not show any general variance in efficiency or selectivity with respect to the alcohols and follow the trend of alcohol reactivity. However, when it comes to the nucleophile, the eight catalysts show general and specific variances in the efficiency and selectivity to perform the desired substitution. Interestingly, the selectivity of the alcohols to produce the desired substitution products was found to be independent of the electrophilicity of the generated carbocations but highly dependent on the ease of formation of the cation. Catalysts based on iron(III), bismuth(III), and gold(III) show higher conversions for S-, C-, and N-centered nucleophiles, and BiIII was the most efficient catalyst in all combinations. Catalysts based on rhenium(I) or rhenium(VII), palladium(II), and lanthanum(III) were the most efficient in performing the nucleophilic substitution on the various alcohols with the O-centered nucleophiles. These catalysts generate the symmetrical ether as a by-product from the reactions of S-, C-, and N-centered nucleophiles as well, resulting in lower chemoselectivity.

  • 5.
    Biswas, Srijit
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Samec, Joseph S. M.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Gold-catalyzed route to alpha-sulfenylated carbonyl compounds from propargylic alcohols and thiophenol: Scope, limitations, and mechanism2013In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 245, p. 382-ORGN-Article in journal (Other academic)
  • 6.
    Biswas, Srijit
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Watile, Rahul A.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Samec, Joseph S. M.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Tandem Pd/Au-Catalyzed Route to alpha-Sulfenylated Carbonyl Compounds from Terminal Propargylic Alcohols and Thiols2014In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 20, no 8, p. 2159-2163Article in journal (Refereed)
    Abstract [en]

    An efficient and highly atom-economical tandem Pd/Au-catalyzed route to -sulfenylated carbonyl compounds from terminal propargylic alcohols and thiols has been developed. This one-step procedure has a wide substrate scope with respect to substituents at the -position of the alcohol. Both aromatic and aliphatic thiols generated the -sulfenylated carbonyl products in good to excellent yields. A mechanism is proposed in which the reaction proceeds through a Pd-catalyzed regioselective hydrothiolation at the terminal triple bond of the propargyl alcohol followed by an Au-catalyzed 1,2-hydride migration.

  • 7.
    Bunrit, Anon
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Dahlstrand, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Olsson, Sandra K.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Srifa, Pemikar
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Huang, Genping
    Orthaber, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Sjöberg, Per J. R.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Biswas, Srijit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Himo, Fahmi
    Samec, Joseph S. M.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Bronsted Acid-Catalyzed Intramolecular Nucleophilic Substitution of the Hydroxyl Group in Stereogenic Alcohols with Chirality Transfer2015In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 137, no 14, p. 4646-4649Article in journal (Refereed)
    Abstract [en]

    The hydroxyl group of enantioenriched benzyl, propargyl, allyl, and alkyl alcohols has been intramolecularly displaced by uncharged O-, N-, and S-centered nucleophiles to yield enantioenriched tetrahydrofuran, pyrrolidine, and tetrahydrothiophene derivatives with phosphinic acid catalysis. The five-membered heterocyclic products are generated in good to excellent yields, with high degree of chirality transfer, and water as the only side-product. Racemization experiments show that phosphinic acid does not promote S(N)1 reactivity. Density functional theory calculations corroborate a reaction pathway where the phosphinic acid operates as a bifunctional catalyst in the intramolecular substitution reaction. In this mechanism, the acidic proton of the phosphinic acid protonates the hydroxyl group, enhancing the leaving group ability. Simultaneously, the oxo group of phosphinic acid operates as a base abstracting the nucleophilic proton and thus enhancing the nucleophilicity. This reaction will open up new atom efficient techniques that enable alcohols to be used as nucleofuges in substitution reactions in the future.

  • 8.
    Cadu, Alban
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Watile, Rahul
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Biswas, Srijit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Orthaber, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Sjöberg, Per J
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Samec, Joseph
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    One-Pot Synthesis of Keto Thioethers by Palladium/Gold-Catalyzed Click and Pinacol Reactions2014In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 16, no 21, p. 5556-5559Article in journal (Refereed)
    Abstract [en]

    An atom-efficient synthesis of keto thioethers was devised via tandem gold/palladium catalysis. The reaction proceeds through a regioselective thiol attack at the β-position of the alcohol, followed by an alkyl, aryl, or benzyl 1,2-shift. Both acyclic and cyclic systems were studied, in the latter case leading to the ring expansion of cyclic substrates.

  • 9. Casey, Charles P.
    et al.
    Boller, Timothy M.
    Samec, Joseph S. M.
    Reinert-Nash, John R.
    Quantitative Determination of the Regioselectivity of Nucleophilic Addition to η3-Propargyl Rhenium Complexes and Direct Observation of an Equilibrium between η3-Propargyl Rhenium Complexes and Rhenacyclobutenes.2009In: Organometallics, ISSN 0276-7333, E-ISSN 1520-6041, Vol. 28, no 1, p. 123-131Article in journal (Refereed)
    Abstract [en]

    PMe3 adds selectively to the central C of the η3-propargyl complex [C5Me5(CO)2Re(η3-CH2C≡CCMe3)][BF4] (1-t-Bu) to form the metallacyclobutene [C5Me5(CO)2Re(CH2C(PMe3):CCMe3)][BF4] (7). The rate of rearrangement of the metallacyclobutene 7 to η2-alkyne complex [C5Me5(CO)2Re(η2-Me3PCH2C≡CCMe3)][BF4] (8) is independent of phosphine concn., consistent with a dissociative mechanism proceeding via η3-propargyl complex 1-t-Bu. The rate of this rearrangement is 480 times slower than the rate of exchange of PMe3 with the labeled metallacyclobutene 7-d9. This rate ratio provides an indirect measurement of the regioselectivity for addn. of PMe3 to the central C of η3-propargyl complex 1-t-Bu to give 7 compared to addn. to a terminal C to give 8. The addn. of PPh3 to 1-t-Bu gives the metallacyclobutene [C5Me5(CO)2Re(CH2C(PPh3):CCMe3)][BF4] (11). Low-temp. 1H NMR spectra provide evidence for an equil. between metallacyclobutene 11 and η3-propargyl complex 1-t-Bu (Keq ≈ 44 M-1 at -46° and ΔG°(0°) = -1.2 ± 0.2 kcal mol-1). The crystal and mol. structures of [C5Me5(CO)2Re[η2-(Ar2PCH2CH2PPh2)CH2C≡CCMe3]][BF4]·2CH2Cl2 (Ar = 3,5-(CF3)2C6H3) and [C5Me5(CO)2Re(η2-Me3PCH2C≡CCMe3)]Cl·H2O were detd. by x-ray crystallog. [on SciFinder(R)]

  • 10.
    Dawange, Monali
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Galkin, Maxim V.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Samec, Joseph S. M.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Selective Aerobic Benzylic Alcohol Oxidation of Lignin Model Compounds: Route to Aryl Ketones2015In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 7, no 3, p. 401-404Article in journal (Refereed)
    Abstract [en]

    A mild and chemoselective oxidation of the -alcohol in -O-4-ethanoaryl and -O-4-glycerolaryl ethers has been developed. The benzylic alcohols were selectively dehydrogenated to the corresponding ketones in 60-93% yield. A one-pot selective route to aryl ethyl ketones was performed. The catalytic system comprises recyclable heterogeneous palladium, mild reaction conditions, green solvents, and oxygen in air as oxidant. Catalytic amounts of a coordinating polyol were found pivotal for an efficient aerobic oxidation.

  • 11. Ell, Alida H.
    et al.
    Samec, Joseph S. M.
    Brasse, Claudia
    Baeckvall, Jan-E.
    Dehydrogenation of aromatic amines to imines via ruthenium-catalyzed hydrogen transfer.2002In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, no 10, p. 1144-1145Article in journal (Refereed)
    Abstract [en]

    An efficient ruthenium-catalyzed transfer dehydrogenation of amines to imines was achieved under mild conditions using 2,6-dimethoxybenzoquinone (I) or a catalytic amt. of I with MnO2 as oxidant. [on SciFinder(R)]

  • 12.
    Galkin, Maxim
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Samec, Joseph
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Selective Route to 2-Propenyl Aryls Directly from Wood by a Tandem Organosolv and Palladium-Catalysed Transfer Hydrogenolysis2014In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 7, no 8, p. 2154-2158Article in journal (Refereed)
    Abstract [en]

    A tandem organosolv pulping and Pd-catalysed transfer hydrogenolysis depolymerisation and deoxygenation has been developed. The tandem process generated 2-methoxy-4-(prop-1-enyl)phenol in 23 % yield (92 % theoretical monomer yield) starting from pine wood and 2,6-dimethoxy-4-(prop-1-enyl)phenol in 49 % yield (92 % theoretical monomer yield) starting from birch wood. Only endogenous hydrogen from wood was consumed, and the reaction was performed using green solvents.

  • 13.
    Galkin, Maxim V.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Dahlstrand, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Samec, Joseph S. M.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Mild and Robust Redox-Neutral Pd/C-Catalyzed Lignol -O-4 Bond Cleavage Through a Low-Energy-Barrier Pathway2015In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 8, no 13, p. 2187-2192Article in journal (Refereed)
    Abstract [en]

    A Pd/C catalyzed redox neutral CO bond cleavage of 2-aryloxy-1-arylethanols has been developed. The reactions are carried out at 80 degrees C, in air, using a green solvent system to yield the aryl ketones in near quantitative yields. Addition of catalytic amounts of a hydrogen source to the reaction mixture activates the catalyst to proceed through a low energy barrier pathway. Initial studies support a transfer hydrogenolysis reaction mechanism that proceeds through an initial dehydrogenation followed by an enol adsorption to Pd/C and a reductive CO bond cleavage.

  • 14.
    Galkin, Maxim V.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Sawadjoon, Supaporn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Rohde, Volker
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Dawange, Monali
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Samec, Joseph S. M.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Mild Heterogeneous Palladium-Catalyzed Cleavage of beta-O-4 '-Ether Linkages of Lignin Model Compounds and Native Lignin in Air2014In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 6, no 1, p. 179-184Article in journal (Refereed)
    Abstract [en]

    A mild and robust heterogeneous palladium-catalyzed CO bond cleavage of 2-aryloxy-1-arylethanols using formic acid as reducing agent in air was developed. The cleaved products were isolated in 92-98% yield; and by slightly varying the reaction conditions, a ketone, an alcohol, or an alkane can be generated in near-quantitative yield. This reaction is applicable to cleaving the -O-4-ether bond found in lignin polymers of different origin. The reaction was performed on a lignin polymer model to generate either the monomeric aryl ketone or alkane in a quantitative yield. Moderate depolymerization was achieved with native lignin at similar reaction conditions. Mechanistic studies under kinetic control indicate that an initial palladium-catalyzed dehydrogenation of the alcohol is followed by insertion of palladium to an enol equivalent. A palladium-formato complex reductively cleaves the palladium-enolate complex to generate the ketone.

  • 15.
    Howard, Fredrick
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Sawadjoon, Supaporn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Samec, Joseph S. M.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    A chemoselective route to either 4-methyl-2,4-diphenyl-2-pentene or 1,1,3-trimethyl-3-phenylindane from 2-phenylpropan-2-ol mediated by BiBr3: a mechanistic study2010In: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 51, no 32, p. 4208-4210Article in journal (Refereed)
    Abstract [en]

    The reaction of 2-phenylpropan-2-ol mediated by BiBr3 can, through control of the temp., yield selectively either 4-methyl-2,4-diphenyl-2-pentene or 1,1,3-trimethyl-3-phenylindane. A reaction mechanism that proceeds via 1-methylstyrene is disclosed.

  • 16. Ibrahem, Ismail
    et al.
    Samec, Joseph S. M.
    Baeckvall, Jan E.
    Cordova, Armando.
    Enantioselective addition of aldehydes to amines via combined catalytic biomimetic oxidation and organocatalytic C-C bond formation.2005In: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 46, no 23, p. 3965-3968Article in journal (Refereed)
    Abstract [en]

    The biomimetic catalytic enantioselective addn. of aldehydes to amines is reported. This was accomplished by combining biomimetic coupled catalytic aerobic oxidn. of amines involving ruthenium-induced dehydrogenation and organocatalytic asym. Mannich reactions. The one-pot reactions furnished β-amino aldehyde and α-amino acid derivs. in high yields with excellent chemoselectivity and enantioselectivity. [on SciFinder(R)]

  • 17. Mirzaei, Anvar
    et al.
    Biswas, Srijit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Samec, Joseph
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Iron(III)-Catalyzed Nucleophilic Substitution of the Hydroxy Group in Benzoin by Alcohols2012In: Synthesis (Stuttgart), ISSN 0039-7881, E-ISSN 1437-210X, Vol. 44, no 8, p. 1213-1218Article in journal (Refereed)
    Abstract [en]

    The etherification reaction between benzoin derivatives and alcohols catalyzed by iron(III) proceeds in moderate to good yields. Other metal complexes showed either low reactivity or low chemoselectivity where oxidation of benzoin to benzil was a competing reaction. The iron source operated as a catalyst where 5 mol% of iron(III) generate the 2-alkoxy-1,2-diphenylethan-1-one in 50% yield. With an optimum of 25 mol% of catalyst, the desired ether was obtained in 85% yield. The etherification of benzoin and an alcohol proceed to generate the desired product in polar solvents such as 1,2-dichloroethane, whereas less polar solvents promote the competing oxidation to generate the benzil; polar coordinating solvents such as tetrahydrofuran inhibited the reaction. The efficiency of the reaction is found to be dependent on nucleophile where an optimum of 30 equivalents of alcohol was observed. With electron-­donating substituents on the aromatic ring, the etherification was followed by oxidation to generate the benzil. Moderate yields of etherification product were obtained by monitoring the reaction progress with electron-rich substrates and quenching the reaction after two hours.

  • 18. Pamies, Oscar
    et al.
    Ell, Alida H.
    Samec, Joseph S. M.
    Hermanns, Nina
    Backvall, Jan-E.
    An efficient and mild ruthenium-catalyzed racemization of amines: application to the synthesis of enantiomerically pure amines.2002In: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 43, no 26, p. 4699-4702Article in journal (Refereed)
    Abstract [en]

    An efficient and mild Ru-catalyzed racemization of amines under transfer hydrogenation conditions is reported. A significant advantage of this new procedure is that the ruthenium hydrogen transfer catalysts allow high functional group tolerance. Interestingly, both primary and secondary amines were efficiently racemized under these conditions. We also report on the combination of this new amine racemization with an enzymic kinetic resoln. of primary amines. [on SciFinder(R)]

  • 19. Privalov, Timofei
    et al.
    Samec, Joseph S. M.
    Baeckvall, Jan-E.
    DFT study of an inner-sphere mechanism in the hydrogen transfer from a hydroxycyclopentadienyl ruthenium hydride to imines.2007In: Organometallics, ISSN 0276-7333, E-ISSN 1520-6041, Vol. 26, no 11, p. 2840-2848Article in journal (Refereed)
    Abstract [en]

    A combination of the DFT method with the computational description of environmental effects by solvent was applied to a theor. study of the H transfer to imines by [2,3,4,5-Ph4(η5-C4COH)Ru(CO)2H] (2) within a mol. model that closely mimics the authentic reaction conditions. A consistent polarizable continuum solvent model (PCM) was instrumental and necessary in achieving stability of the computational model. Environmental effects by solvent were also considered in an extended model with an addn. of explicit solvent mols. within the PCM. The study elucidates an inner-sphere mechanism. Intermediate complexes and transition states were characterized. Three distinct energy barriers along the reaction coordinate are predicted when solvent effects are taken into account. The imine coordinates to Ru via ring slippage with an energy barrier of ∌15 kcal/mol. Close in energy (12 kcal/mol) is the transition state of the hydride transfer, which gives an (η2-cyclopentadienone)ruthenium amine intermediate. The presence of Ph groups on the Cp ring facilitates the ring slippage that occurs on imine coordination. This η2-intermediate finally rearranges to the corresponding (η4-cyclopentadienone)ruthenium amine complex via a transition state at 9 kcal/mol. The stable Ru amine complex was verified against an x-ray structure of the corresponding complex. Inclusion of the solvent (by PCM or explicit mols.) was required to stabilize low-hapticity intermediates and transition state structures. [on SciFinder(R)]

  • 20. Samec, Joseph
    et al.
    Enquist, Karl
    Cordova, Armando.
    Method for improving properties of cellulose-based fibrous sheet-formed materials for use in medical goods.2011Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    A method for improving surface strength, fiber tear or linting of a sheet-formed fibrous material formed from an aq. slurry of cellulose fiber by spraying a face of the material with a chem. formulation consisting of a polymer contg. at least two carboxylic groups per mol. such as polyacrylic acid or polysaccharide or their sodium and potassium salts and aliph. mono-, di-, or three- basic carboxylic acid with mol. wt. of 40-500 Da in an aq. carrier, keeping the coated face at ≥ 50° for time sufficient to gain the desired improvement including drying time of the material is presented. The chem. formulation is sprayed on the wet laid sheet-formed material at the wet end of a paper machine in an amt. of 1-5% by wt. of the sheet-formed material in a dry state. Also disclosed is a sheet-formed fibrous material prepd. by the method and a laminated product of medical grade comprising the sheet-formed fibrous material and a polymer film. [on SciFinder(R)]

  • 21. Samec, Joseph
    et al.
    Enquist, Karl
    Cordova, Armando.
    Method for improving properties of cellulose-based fibrous sheet-formed materials for use in medical goods.2011In: Patent World, ISSN 0950-2513, no WO2011039325A2Article in journal (Other (popular science, discussion, etc.))
    Abstract [en]

    A method for improving surface strength, fiber tear or linting of a sheet-formed fibrous material formed from an aq. slurry of cellulose fiber by spraying a face of the material with a chem. formulation consisting of a polymer contg. at least two carboxylic groups per mol. such as polyacrylic acid or polysaccharide or their sodium and potassium salts and aliph. mono-, di-, or three- basic carboxylic acid with mol. wt. of 40-500 Da in an aq. carrier, keeping the coated face at ≥ 50° for time sufficient to gain the desired improvement including drying time of the material is presented. The chem. formulation is sprayed on the wet laid sheet-formed material at the wet end of a paper machine in an amt. of 1-5% by wt. of the sheet-formed material in a dry state. Also disclosed is a sheet-formed fibrous material prepd. by the method and a laminated product of medical grade comprising the sheet-formed fibrous material and a polymer film. [on SciFinder(R)]

  • 22. Samec, Joseph
    et al.
    Lundstedt, Anna
    Sawadjoon, Supaporn
    REDUCTION OF C-0 BONDS BY CATALYTIC TRANSFER HYDROGENOLYSIS2012Patent (Other (popular science, discussion, etc.))
  • 23. Samec, Joseph S. M.
    et al.
    Backvall, Jan-E.
    Ruthenium-catalyzed transfer hydrogenation of imines by propan-2-ol in benzene.2002In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 8, no 13, p. 2955-2961Article in journal (Refereed)
    Abstract [en]

    Transfer hydrogenation of a variety of different imines to the corresponding amines by propan-2-ol in benzene catalyzed by [Ru2(CO)4(Ό-H)(C4Ph4COHOCC4Ph4)] (1) has been studied. The reaction is highly efficient with turnover frequencies of over 800 per h, and the product amines were obtained in excellent yields. A remarkable concn. dependence of propan-2-ol was obsd. when the reaction was run in benzene as cosolvent. An optimum was obtained at 24 equiv of propan-2-ol to imine, and further increase of the propan-2-ol led to a dramatic decrease in rate. Also the use of polar cosolvents with 24 equiv of propan-2-ol gave a low rate. It was found that ketimines react faster than aldimines and that electron-donating substituents on the imine increase the rate of the catalytic transfer hydrogenation. Electron-withdrawing substituents decreased the rate. An isomerization was obsd. with imines having an α-hydrogen at the N-alkyl substituent, which is in accordance with a mechanism involving a ruthenium-amine intermediate. It was demonstrated that the ruthenium-amine complex from α-methylbenzylamine, corresponding to the postulated intermediate, can replace 1 as catalyst in the transfer hydrogenation of imines. A primary deuterium isotope effect of kCH/CD = 2.7 ± 0.25 was obsd. when 2-deuterio-propan-2-ol was used in place of propan-2-ol in the transfer hydrogenation of N-phenyl-(1-phenylethylidene)amine. [on SciFinder(R)]

  • 24. Samec, Joseph S. M.
    et al.
    Baeckvall, Jan-E.
    Andersson, Pher G.
    Brandt, Peter.
    Mechanistic aspects of transition metal-catalyzed hydrogen transfer reactions.2006In: Chemical Society Reviews, ISSN 0306-0012, E-ISSN 1460-4744, Vol. 35, no 3, p. 237-248Article in journal (Refereed)
    Abstract [en]

    A review. In this tutorial review recent mechanistic studies on transition metal-catalyzed hydrogen transfer reactions are discussed. A common feature of these reactions is that they involve metal hydrides, which may be monohydrides or dihydrides. An important question is whether the substrate coordinates to the metal (inner-sphere hydrogen transfer) or if there is a direct concerted transfer of hydrogen from the metal to substrate (outer-sphere hydrogen transfer). Both exptl. and theor. studies are reviewed. [on SciFinder(R)]

  • 25. Samec, Joseph S. M.
    et al.
    Ell, Alida H.
    Aaberg, Jenny B.
    Privalov, Timofei
    Eriksson, Lars
    Baeckvall, Jan-E.
    Mechanistic Study of Hydrogen Transfer to Imines from a Hydroxycyclopentadienyl Ruthenium Hydride. Experimental Support for a Mechanism Involving Coordination of Imine to Ruthenium Prior to Hydrogen Transfer.2006In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 128, no 44, p. 14293-14305Article in journal (Refereed)
    Abstract [en]

    Ruthenium hydroxycyclopentadienyl complex exhibits activity in hydrogenation of imines; the mechanism of the reaction was explored by isolation of the intermediates, evaluation of substituent effects and kinetic isotope effect detn. Reaction of [(Cp'OH)Ru(CO)2H] (2; Cp'OH = η5-2,3,4,5-Ph4C4COH) with different imines afforded ruthenium amine cyclopentadienone [(η4-Ph4C4O)Ru(NHR1R2)(CO)2] complexes at low temps. At higher temps. in the presence of 2, the complexes decompd. to give mixed hydroxycyclopentadiene-cyclopentadienone dimer [Ru2(CO)4(Ό-H)(Ό-C4Ph4COHOCC4Ph4)] (1) and free amine. Electron-rich imines gave ruthenium amine complexes with 2 at a lower temp. than did electron-deficient imines. The negligible deuterium isotope effect (kRuHOH/kRuDOD = 1.05) obsd. in the reaction of 2 with N-phenyl[1-(4-methoxyphenyl)ethylidene]amine (12) shows that neither hydride (RuH) nor proton (OH) is transferred to the imine in the rate-detg. step. In the dehydrogenation of N-phenyl-1-phenylethylamine (4) to the corresponding imine (8) by cyclopentadienone complex [(η4-Ph4C4CO)Ru(CO)2] (A), the kinetic isotope effects obsd. support a stepwise hydrogen transfer where the isotope effect for C-H cleavage (kCHNH/kCDNH = 3.24) is equal to the combined (C-H, N-H) isotope effect (kCHNH/kCDND = 3.26). Hydrogenation of N-methyl(1-phenylethylidene)amine (14) by 2 in the presence of the external amine trap N-methyl-1-(4-methoxyphenyl)ethylamine (16) afforded 90-100% of complex [(η4-Ph4C4CO)Ru(CO)2[NHMe(CHPhMe)]] (15), which is the complex between ruthenium and the amine newly generated from the imine. At -80° the reaction of hydride 2 with cyclohexylideneamine 4-PhCH2NH-C6H9:NPh (18), with an internal amine trap, only afforded [(η4-Ph4C4CO)(CO)2Ru[NH(Ph)(C6H10-4-NHCH2Ph)]] (19), where the ruthenium binds to the amine originating from the imine, showing that neither complex A nor the diamine is formed. Above -8° complex 19 rearranged to the thermodynamically more stable [(η4-Ph4C4CO)(CO)2Ru[NH(PhCH2)(C6H10-4-NHPh)]] (20). These results are consistent with an inner sphere mechanism in which the substrate coordinates to ruthenium prior to hydrogen transfer and are difficult to explain with the outer sphere pathway previously proposed. [on SciFinder(R)]

  • 26. Samec, Joseph S. M.
    et al.
    Ell, Alida H.
    Baeckvall, Jan-E.
    Efficient ruthenium-catalyzed aerobic oxidation of amines by using a biomimetic coupled catalytic system.2005In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 11, no 8, p. 2327-2334Article in journal (Refereed)
    Abstract [en]

    Efficient aerobic oxidn. of amines was developed using a biomimetic coupled catalytic system involving a Ru-induced dehydrogenation. The principle for this aerobic oxidn. is that the electron transfer from the amine to O2 occurs stepwise via coupled redox systems and this leads to a low-energy electron transfer. A substrate-selective Ru catalyst dehydrogenates the amine and the H atoms abstracted are transported to an electron-rich quinone (2a; 2,6-dimethoxy-p-benzoquinone). The hydroquinone thus formed is subsequently reoxidized by air with the aid of an oxygen-activating [Co(salen)]-type complex (27; [Co(MeN(CH2CH2CH2N:CHC6H4O-2)2)]). The reaction can be used for the prepn. of ketimines and aldimines in good to high yields from the appropriate corresponding amines. The reaction proceeds with high selectivity, and the catalytic system tolerates air without being deactivated. The rate of the dehydrogenation was studied by using quinone 2a as the terminal oxidant. A catalytic cycle in which the amine promotes the dissocn. of the dimeric catalyst (OC)2(η5-Ph4C5OH)Ru(Ό-H)Ru(η5-OC5Ph4)(CO)2 is presented. [on SciFinder(R)]

  • 27. Samec, Joseph S. M.
    et al.
    Ell, Alida H.
    Baeckvall, Jan-E.
    Mechanism of hydrogen transfer to imines from a hydroxycyclopentadienyl ruthenium hydride. Support for a stepwise mechanism.2004In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, no 23, p. 2748-2749Article in journal (Refereed)
    Abstract [en]

    The negligible double kinetic deuterium isotope effect (kHH/kDD = 1.05) in the reaction where [2,3,4,5-Ph4(η5-C4COH)]Ru(CO)2H (2) transfers a hydride and a proton to N-phenyl-[1-(4-methoxyphenyl)ethylidene]amine (4) indicates that no bond to hydrogen is broken or formed in the rate-detg. step. [on SciFinder(R)]

  • 28. Samec, Joseph S. M.
    et al.
    Grubbs, Robert H.
    Bidentate N,O-prolinate ruthenium benzylidene catalyst highly active in RCM of disubstituted dienes.2007In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, no 27, p. 2826-2828Article in journal (Refereed)
    Abstract [en]

    Bidentate N,O-prolinate ruthenium benzylidene I was prepd. from com. available L-proline and Grubbs catalyst. The catalytic activity of I in ring-closing metathesis (RCM) of functionalized disubstituted dienes at 30° is disclosed. [on SciFinder(R)]

  • 29. Samec, Joseph S. M.
    et al.
    Keitz, Benjamin K.
    Grubbs, Robert H.
    Latent ruthenium olefin metathesis catalysts featuring a phosphine or an N-heterocyclic carbene ligand.2010In: Journal of Organometallic Chemistry, ISSN 0022-328X, E-ISSN 1872-8561, Vol. 695, no 14, p. 1831-1837Article in journal (Refereed)
    Abstract [en]

    The synthesis and characterization of latent 18-electron ruthenium benzylidene complexes (PCy3)((κN,O)-picolinate)2RuCHPh (5) and (H2IMes)((κN,O)-picolinate)2RuCHPh (6) are described. Both complexes appear as two isomers. The ratio between the isomers is dependent on L-type ligand. The complexes are inactive in ring-closing metathesis and ring-opening metathesis polymn. reactions even at elevated temps. in the absence of stimuli. Upon addn. of HCl, complexes 5 and 6 become highly active in olefin metathesis reactions. The advantage of the latent catalysts is demonstrated in the ring-opening metathesis polymn. of dicyclopentadiene, where the latency of 6 assures adequate mixing of catalyst and monomer before initiation. Trapping expts. suggests that the acid converts the 18-electron complexes into their corresponding highly olefin metathesis active 14-electron benzylidenes. [on SciFinder(R)]

  • 30. Samec, Joseph S. M.
    et al.
    Mony, Laetitia
    Baeckvall, Jan-E.
    Efficient ruthenium catalyzed transfer hydrogenation of functionalized imines by isopropanol under controlled microwave heating.2005In: Canadian journal of chemistry (Print), ISSN 0008-4042, E-ISSN 1480-3291, Vol. 83, no 6-7, p. 909-916Article in journal (Refereed)
    Abstract [en]

    Transfer hydrogenation of various functionalized imines by isopropanol catalyzed by [Ru(CO)2(Ph4C4CO)]2 (I) was studied. The use of either an oil bath or controlled microwave heating in toluene led to an efficient procedure with high turnover frequencies and the product amines were obtained in high yields. An advantage with catalyst I over the conventional [Ru2(CO)4(Ό-H)(Ph4C4COHOCC4Ph4)] (II) is the absence of an initiation period, which results in a faster reaction with I as compared to II. [on SciFinder(R)]

  • 31. Samec, Joseph S.M.
    et al.
    Grubbs, Robert H.
    Ruthenium carbene complexes bearing an anionic carboxylate chelated to a hemilabile ligand2008In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 14, no 9, p. 2686-92Article in journal (Refereed)
    Abstract [en]

    A series of bidentate ruthenium-based NHC complexes with the general formula [(H(2)IMes)(kappa(2)-L-COO)ClRu=CHPh)], where L is either PAr(3), HNR(2), or ROR, were prepared from commercially available [(H(2)IMes)(PCy(3))Cl(2)Ru(CHPh)] (2) and the appropriate ligand. The catalytic activities of the complexes were evaluated in ring-closing metathesis reactions. The type of donor ligand has a major impact on both the initiation behavior and also the stability of the complexes. Upon addition of CuCl to the reaction mixture the initiation is improved for the phosphine or amine containing chelates. For the P,O-chelate, the fast initiation was followed by decomposition. In the case of the N,O-containing chelate, a stable catalytic system was achieved. Trapping experiments support that the nitrogen lone-pair reversibly coordinates CuCl during the reaction.[on SciFinder (R)]

  • 32.
    Sawadjoon, Supaporn
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Galkin, Maxim
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Dahlstrand, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Rohde, Volker
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Samec, Joseph S. M.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Selective palladium-catalyzed reductive cleavage of beta-O-4-glucolaryl ether linkages in lignin model compounds2013In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 245, p. 15-ORGN-Article in journal (Other academic)
  • 33.
    Sawadjoon, Supaporn
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Lundstedt, Anna
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Physical Organic Chemistry.
    Samec, Joseph
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Pd-Catalyzed Transfer Hydrogenolysis of Primary, Secondary, and Tertiary Benzylic Alcohols by Formic Acid: A Mechanistic Study2013In: ACS Catalysis, ISSN 2155-5435, Vol. 3, no 4, p. 635-642Article in journal (Refereed)
    Abstract [en]

    A palladium-catalyzed transfer hydrogenolysis of primary, secondary, and tertiary benzylic alcohols by formic acid has been developed and studied. The product hydrocarbons were obtained in excellent yields from bothsecondary and tertiary benzylic alcohols and in good yields for primary benzylicalcohols. The rate of disappearance of 1-phenylethanol (1) follows zero-order dependence in 1 and first-order dependence in formic acid and palladium. Catalytic amounts of base inhibit a competing disproportionation reaction ofalcohol to alkane and ketone, and an optimum was obtained when 5 equiv ofbase to palladium was used Deuterium kinetic isotope studies for the transferhydrogenolysis reveal individual isotope effects for the hydridic position (k(CHOH)/k(CDOH) = 2.26 +/- 0.24) and the protic position (k(CHOH)/k(CHOD) = 0.62 +/- 0.06) of the formic acid. Simultaneous deuteration in both positions offormic acid gave a combined isotope effect of (k(CHOH)/k(CDOD) = 1.41 +/- 0.11). We propose a mechanism involving the following steps: a competitive inhibition of the open palladium site by adsorption of the formate anion to generate formato-palladium species, followed by a reversible protonation and arate-limiting hydride transfer to obtain the active palladium with chemisorbed hydrogen that performs the hydrogenolysis of the alcohol in a fast reaction step.

  • 34.
    Sawadjoon, Supaporn
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Orthaber, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Sjöberg, Per J. R.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Eriksson, Lars
    Samec, Joseph S. M.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Equilibrium Study of Pd(dba)2 and P(OPh)3 in the Pd-Catalyzed Allylation of Aniline by Allyl Alcohol2014In: Organometallics, ISSN 0276-7333, E-ISSN 1520-6041, Vol. 33, no 1, p. 249-253Article in journal (Refereed)
    Abstract [en]

    Reaction of Pd(dba)2 and P(OPh)3 shows a unique equilibrium where the Pd[P(OPh)3]3 complex is favored over both Pd(dba)[P(OPh)3]2 and Pd[P(OPh)3]4 complexes at room temperature. At a lower temperature, Pd[P(OPh)3]4 becomes the most abundant complex in solution. X-ray studies of Pd[P(OPh)3]3 and Pd(dba)[P(OPh)3]2 complexes show that both complexes have a trigonal geometry with a Pd–P distance of 2.25 Å due to the π-acidity of the phosphite ligand. In solution, pure Pd(dba)[P(OPh)3]2 complex equilibrates to the favored Pd[P(OPh)3]3 complex, which is the most stable complex of those studied, and also forms the most active catalytic species. This catalyst precursor dissociates one ligand to give the reactive Pd[P(OPh)3]2, which performs an oxidative addition of nonmanipulated allyl alcohol to generate the π-allyl-Pd[P(OPh)3]2 intermediate according to ESI-MS studies.

  • 35.
    Sawadjoon, Supaporn
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry, Organic Chemistry.
    Samec, Joseph S. M.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry, Organic Chemistry.
    An atom efficient route to N-aryl and N-alkyl pyrrolines by transition metal catalysis2011In: Organic and biomolecular chemistry, ISSN 1477-0520, E-ISSN 1477-0539, Vol. 9, no 7, p. 2548-2554Article in journal (Refereed)
    Abstract [en]

    The synthesis of N-aryl, N-tosyl, and N-alkyl pyrrolines from allyl alcohols and amines has been developed. The reaction sequence includes a palladium-catalyzed allylation step in which non-manipulated allyl alcohol is used to generate the diallylated amine in good to excellent yield. An excess of allyl alcohol was necessary for efficient diallylation of the amine, where the excess alcohol could be recycled three times. For aryl and tosyl amines, Pd[P(OPh)(3)](4) was used and for benzyl and alkyl amines a catalytic system comprising Pd(OAc)(2), (PBu3)-Bu-n, and BEt3 was used. Both the electronic properties and the steric influence of the amine affected the efficiency of the allylation. The isolated diallylated amines were transformed into their corresponding pyrrolines by ring-closing metathesis catalyzed by (H(2)IMes)(PCy3)Cl2RuCHPh in good to excellent yield. A one-pot reaction was developed in which aniline was transformed into the corresponding pyrroline without isolating the diallylated intermediate. This one-pot reaction was successfully scaled-up to 1 mL of aniline in which the N-phenyl pyrroline was isolated in 95% yield. The versatility of the reaction in which 3-methyl-1-phenyl pyrroline was prepared in two-steps was demonstrated.

  • 36.
    Sawadjoon, Supaporn
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Samec, Joseph S. M.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Mechanistic studies and synthetic applications of palladium-catalyzed direct aminations of allylic alcohols2013In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 245, p. 645-ORGN-Article in journal (Other academic)
  • 37.
    Sawadjoon, Supaporn
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Sjöberg, Per J R
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Orthaber, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Matsson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Physical Organic Chemistry.
    Samec, Joseph S M
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Mechanistic Insights into the Pd-Catalyzed Direct Amination of Allyl Alcohols: Evidence for an Outer-sphere Mechanism Involving a Palladium Hydride Intermediate2014In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 20, no 6, p. 1520-1524Article in journal (Refereed)
    Abstract [en]

    The mechanism of direct amination of allyl alcohol by a palladium triphenylphosphite complex has been explored. Labelling studies show that the reaction proceeds through a π-allylpalladium intermediate. A second-order dependence of reaction rate on allyl alcohol concentration was observed. Kinetic isotope effect studies and ESI-MS studies are in agreement with a reaction proceeding through a palladium hydride intermediate in which both O-H bond and C-O bond cleavages are involved in rate-determining steps. A stereochemical study supports an outer-sphere nucleophilic attack of the π-allylpalladium intermediate giving complete chiral transfer from starting material to product.

  • 38.
    Tšupova, Svetlana
    et al.
    Ruprecht-Karls-Universität Heidelberg.
    Cadu, Alban
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Stuck, Fabian
    Ruprecht-Karls-Universität Heidelberg.
    Rominger, Frank
    Ruprecht-Karls-Universität Heidelberg.
    Rudolph, Matthias
    Ruprecht-Karls-Universität Heidelberg.
    Samec, Joseph
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry. Stockholm University.
    Hashmi, A. Stephen K.
    Ruprecht-Karls-Universität Heidelberg.
    Dual Gold (I) Catalysed Cyclisation of Dialkynyl Pyridinium saltsManuscript (preprint) (Other academic)
    Abstract [en]

    Novel dialkynyl pyridines were synthesised and protected as alkyl salts for dual gold (I) catalysed cycloisomerisation. Different alkyl groups and counter ions were screened for the salts, with benzyl and PF6- providing the best results. The cyclisation led to NMR yields of >95% being obtained for a number of substrates. Step-wise hydrogenation of products could be carried out in one-pot by Pd/C, with selective reduction of the double bonds, followed by deprotection of the Bn group.

  • 39. Wallenhorst, Carolin
    et al.
    Axenov, Kirill V.
    Kehr, Gerald
    Samec, Joseph S. M.
    Froehlich, Roland
    Erker, Gerhard.
    A salt metathesis route to ruthenium carbene complex isomers with pyridine dicarboxamide-derived chelate pincer ligands.2007In: Zeitschrift für Naturforschung. B, A journal of chemical sciences, ISSN 0932-0776, E-ISSN 1865-7117, Vol. 62, no 6, p. 783-790Article in journal (Refereed)
    Abstract [en]

    Reaction of the doubly deprotonated pyridine 2,6-dicarboxamido ligand (1) with (PCy3)2Cl2Ru:CHPh (3a) in THF gave a mixt. of (lig)(PCy3)Ru:CHPh isomers (4). The pentane sol. N,N,O-4 isomer was isolated by extn. and characterized by x-ray diffraction. The O,N,O-4 isomer was identified in the residue. Single crystals of the closely related complex (lig)(NHC)Ru:CHPh, O,N,O-5, were obtained from the reaction of 1 with (NHC)(PCy3)Cl2Ru:CHPh (3b) and used for the x-ray crystal structure anal. of the system. [on SciFinder(R)]

  • 40.
    Watile, Rahul
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Biswas, Srijit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Samec, Joseph
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    An aqueous and recyclable copper(I)-catalyzed route to α-sulfenylated carbonyl compounds from propargylic alcohols and aryl thiols2013In: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, Vol. 15, no 11, p. 3176-3179Article in journal (Refereed)
    Abstract [en]

    A highly efficient one-step copper(I)-catalyzed method for the synthesis of α-sulfenylated carbonyl compounds from propargylic alcohols and aryl thiols in aqueous media is described. A variety of α-sulfenylated carbonyl compounds can be synthesized in good to excellent yields. The catalyst has been successfully recycled up to 4 times without any loss of activity in an aqueous medium.

1 - 40 of 40
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