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Samec, Joseph S. M.
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Publications (10 of 41) Show all publications
Samec, J. (2018). Catalytic C-O bond cleavage in non-derivatized alcohols. Paper presented at 255th National Meeting and Exposition of the American-Chemical-Society (ACS) - Nexus of Food, Energy, and Water, MAR 18-22, 2018, New Orleans, LA, USA. Abstract of Papers of the American Chemical Society, 255
Open this publication in new window or tab >>Catalytic C-O bond cleavage in non-derivatized alcohols
2018 (English)In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 255Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2018
National Category
Organic Chemistry
Identifiers
urn:nbn:se:uu:diva-365866 (URN)000435537702640 ()
Conference
255th National Meeting and Exposition of the American-Chemical-Society (ACS) - Nexus of Food, Energy, and Water, MAR 18-22, 2018, New Orleans, LA, USA
Available from: 2018-11-22 Created: 2018-11-22 Last updated: 2018-11-22Bibliographically approved
Bunrit, A., Dahlstrand, C., Olsson, S. K., Srifa, P., Huang, G., Orthaber, A., . . . Samec, J. S. M. (2015). Bronsted Acid-Catalyzed Intramolecular Nucleophilic Substitution of the Hydroxyl Group in Stereogenic Alcohols with Chirality Transfer. Journal of the American Chemical Society, 137(14), 4646-4649
Open this publication in new window or tab >>Bronsted Acid-Catalyzed Intramolecular Nucleophilic Substitution of the Hydroxyl Group in Stereogenic Alcohols with Chirality Transfer
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2015 (English)In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 137, no 14, p. 4646-4649Article in journal (Refereed) Published
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.

National Category
Chemical Sciences
Identifiers
urn:nbn:se:uu:diva-253254 (URN)10.1021/jacs.5b02013 (DOI)000353177100014 ()25803790 (PubMedID)
Available from: 2015-06-12 Created: 2015-05-25 Last updated: 2017-12-04Bibliographically approved
Galkin, M. V., Dahlstrand, C. & Samec, J. S. M. (2015). Mild and Robust Redox-Neutral Pd/C-Catalyzed Lignol -O-4 Bond Cleavage Through a Low-Energy-Barrier Pathway. ChemSusChem, 8(13), 2187-2192
Open this publication in new window or tab >>Mild and Robust Redox-Neutral Pd/C-Catalyzed Lignol -O-4 Bond Cleavage Through a Low-Energy-Barrier Pathway
2015 (English)In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 8, no 13, p. 2187-2192Article in journal (Refereed) Published
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.

Keywords
heterogeneous catalysis, lignin, palladium, reaction mechanisms, transfer hydrogenolysis
National Category
Chemical Sciences
Identifiers
urn:nbn:se:uu:diva-259649 (URN)10.1002/cssc.201500117 (DOI)000357619000004 ()25925736 (PubMedID)
Funder
Swedish Energy Agency
Available from: 2015-08-20 Created: 2015-08-10 Last updated: 2017-12-04Bibliographically approved
Dawange, M., Galkin, M. V. & Samec, J. S. M. (2015). Selective Aerobic Benzylic Alcohol Oxidation of Lignin Model Compounds: Route to Aryl Ketones. ChemCatChem, 7(3), 401-404
Open this publication in new window or tab >>Selective Aerobic Benzylic Alcohol Oxidation of Lignin Model Compounds: Route to Aryl Ketones
2015 (English)In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 7, no 3, p. 401-404Article in journal (Refereed) Published
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.

Keywords
biomass valorization, heterogeneous catalysis, lignin, oxidation, palladium
National Category
Chemical Sciences
Identifiers
urn:nbn:se:uu:diva-246820 (URN)10.1002/cctc.201402825 (DOI)000349147100005 ()
Available from: 2015-03-11 Created: 2015-03-10 Last updated: 2017-12-04Bibliographically approved
Sawadjoon, S., Orthaber, A., Sjöberg, P. J. R., Eriksson, L. & Samec, J. S. M. (2014). Equilibrium Study of Pd(dba)2 and P(OPh)3 in the Pd-Catalyzed Allylation of Aniline by Allyl Alcohol. Organometallics, 33(1), 249-253
Open this publication in new window or tab >>Equilibrium Study of Pd(dba)2 and P(OPh)3 in the Pd-Catalyzed Allylation of Aniline by Allyl Alcohol
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2014 (English)In: Organometallics, ISSN 0276-7333, E-ISSN 1520-6041, Vol. 33, no 1, p. 249-253Article in journal (Refereed) Published
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.

National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-218947 (URN)10.1021/om4009873 (DOI)000329879900029 ()
Available from: 2014-02-27 Created: 2014-02-20 Last updated: 2017-12-05Bibliographically approved
Sawadjoon, S., Sjöberg, P. J., Orthaber, A., Matsson, O. & Samec, J. S. (2014). Mechanistic Insights into the Pd-Catalyzed Direct Amination of Allyl Alcohols: Evidence for an Outer-sphere Mechanism Involving a Palladium Hydride Intermediate. Chemistry - A European Journal, 20(6), 1520-1524
Open this publication in new window or tab >>Mechanistic Insights into the Pd-Catalyzed Direct Amination of Allyl Alcohols: Evidence for an Outer-sphere Mechanism Involving a Palladium Hydride Intermediate
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2014 (English)In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 20, no 6, p. 1520-1524Article in journal (Refereed) Published
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.

National Category
Analytical Chemistry Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-215613 (URN)10.1002/chem.201303431 (DOI)000337300000008 ()24403056 (PubMedID)
Available from: 2014-01-15 Created: 2014-01-15 Last updated: 2017-12-06Bibliographically approved
Galkin, M. V., Sawadjoon, S., Rohde, V., Dawange, M. & Samec, J. S. M. (2014). Mild Heterogeneous Palladium-Catalyzed Cleavage of beta-O-4 '-Ether Linkages of Lignin Model Compounds and Native Lignin in Air. ChemCatChem, 6(1), 179-184
Open this publication in new window or tab >>Mild Heterogeneous Palladium-Catalyzed Cleavage of beta-O-4 '-Ether Linkages of Lignin Model Compounds and Native Lignin in Air
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2014 (English)In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 6, no 1, p. 179-184Article in journal (Refereed) Published
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.

Keywords
heterogeneous catalysis, cleavage reactions, green chemistry, palladium, polymers, lignin
National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-220309 (URN)10.1002/cctc.201300540 (DOI)000330636800023 ()
Note

De två första författarna delar första författarskapet.

Available from: 2014-03-17 Created: 2014-03-12 Last updated: 2017-12-05Bibliographically approved
Cadu, A., Watile, R., Biswas, S., Orthaber, A., Sjöberg, P. J. & Samec, J. (2014). One-Pot Synthesis of Keto Thioethers by Palladium/Gold-Catalyzed Click and Pinacol Reactions. Organic Letters, 16(21), 5556-5559
Open this publication in new window or tab >>One-Pot Synthesis of Keto Thioethers by Palladium/Gold-Catalyzed Click and Pinacol Reactions
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2014 (English)In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 16, no 21, p. 5556-5559Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2014
Keywords
Gold, Palladium, thioether, catalysis, synthesis
National Category
Organic Chemistry
Identifiers
urn:nbn:se:uu:diva-236857 (URN)10.1021/ol502553p (DOI)000344635200013 ()25325145 (PubMedID)
Available from: 2014-11-24 Created: 2014-11-24 Last updated: 2017-12-05Bibliographically approved
Galkin, M. & Samec, J. (2014). Selective Route to 2-Propenyl Aryls Directly from Wood by a Tandem Organosolv and Palladium-Catalysed Transfer Hydrogenolysis. ChemSusChem, 7(8), 2154-2158
Open this publication in new window or tab >>Selective Route to 2-Propenyl Aryls Directly from Wood by a Tandem Organosolv and Palladium-Catalysed Transfer Hydrogenolysis
2014 (English)In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 7, no 8, p. 2154-2158Article in journal (Refereed) Published
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.

Keywords
Biomass, Lignin Green, Chemistry, Palladium, catalysis
National Category
Organic Chemistry
Research subject
Chemistry with specialization in Organic Chemistry
Identifiers
urn:nbn:se:uu:diva-226637 (URN)10.1002/cssc.201402017 (DOI)000340519500016 ()
Funder
Swedish Energy Agency
Available from: 2014-06-18 Created: 2014-06-18 Last updated: 2017-12-05Bibliographically approved
Biswas, S., Watile, R. A. & Samec, J. S. M. (2014). Tandem Pd/Au-Catalyzed Route to alpha-Sulfenylated Carbonyl Compounds from Terminal Propargylic Alcohols and Thiols. Chemistry - A European Journal, 20(8), 2159-2163
Open this publication in new window or tab >>Tandem Pd/Au-Catalyzed Route to alpha-Sulfenylated Carbonyl Compounds from Terminal Propargylic Alcohols and Thiols
2014 (English)In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 20, no 8, p. 2159-2163Article in journal (Refereed) Published
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.

Keywords
atom efficiency, gold, palladium, sulfenylated carbonyl, tandem catalysis
National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-222173 (URN)10.1002/chem.201304111 (DOI)000330903700007 ()
Available from: 2014-04-10 Created: 2014-04-08 Last updated: 2017-12-05Bibliographically approved
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