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  • 1.
    Akkarasamiyo, Sunisa
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Margalef, Jèssica
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Samec, Joseph S. M.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Nickel-Catalyzed Suzuki-Miyaura Cross-Coupling Reaction of Naphthyl and Quinolyl Alcohols with Boronic Acids2019In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 21, no 12, p. 4782-4787Article in journal (Refereed)
    Abstract [en]

    A nickel-catalyzed C(sp(3))-C(sp(2)) Suzuki cross-coupling of arylboronic acids and (hetero)naphthyl alcohols has been developed. A Ni(dppp) Cl-2 complex showed the highest efficiency and broadest substrate scope. High functional group tolerance has been achieved where 35 compounds could be generated in good to excellent yields, including both primary and secondary benzylic alcohols. Mechanistic studies using multiple NMR techniques as well as ESI-HRMS showed that the C-O cleavage is facilitated by an activation of the benzylic alcohol through formation of a boronic ester intermediate.

  • 2.
    Akkarasamiyo, Sunisa
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sawadjoon, Supaporn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Orthaber, Andreas
    Samec, Joseph S. M.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Tsuji-Trost Reaction of Non-Derivatized Allylic Alcohols2018In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 24, no 14, p. 3488-3498Article in journal (Refereed)
    Abstract [en]

    Palladium-catalyzed allylic substitution of non-derivatized enantioenriched allylic alcohols with a variety of uncharged N-, S-, C- and O-centered nucleophiles using a bidentate BiPhePhos ligand is described. A remarkable effect of the counter ion (X) of the XPd[kappa(2)-BiPhePhos][kappa(3)-C3H5] was observed. When ClPd[kappa(2)-BiPhePhos][eta(3)-C3H5] (complexI) was used as catalyst, non-reproducible results were obtained. Study of the complex by X-ray crystallography, (PNMR)-P-31 spectroscopy, and ESI-MS showed that a decomposition occurred where one of the phosphite ligands was oxidized to the corresponding phosphate, generating ClPd[kappa(1)-BiPhePhosphite-phosphate][eta(3)-C3H5] species (complexII). When the chloride was exchanged to the weaker coordinating OTf- counter ion the more stable Pd[kappa(2)-BiPhePhos][eta(3)-C3H5](+)+[OTf] (-) (complexIII) was formed. ComplexIII performed better and gave higher enantiospecificities in the substitution reactions. ComplexIII was evaluated in Tsuji-Trost reactions of stereogenic non-derivatized allylic alcohols. The desired products were obtained in good to excellent yields (71-98%) and enantiospecificities (73-99%) for both inter- and intramolecular substitution reactions with only water generated as a by-product. The methodology was applied to key steps in total synthesis of (S)-cuspareine and (+)-lentiginosine. A reaction mechanism involving a palladium hydride as a key intermediate in the activation of the hydroxyl group is proposed in the overall transformation.

  • 3.
    Bunrit, Anon
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Uppsala University, Sweden.
    Dahlstrand, Christian
    Srifa, Pemikar
    Olsson, Sandra K.
    Huang, Genping
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Tianjin University, China.
    Biswas, Srijit
    Himo, Fahmi
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Samec, Joseph S. M.
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Uppsala University, Sweden.
    Nucleophilic Substitution of the Hydroxyl Group in Stereogenic Alcohols with Chirality Transfer2016In: Synlett: Accounts and Rapid Communications in Synthetic Organic Chemistry, ISSN 0936-5214, E-ISSN 1437-2096, Vol. 27, no 2, p. 173-176Article in journal (Refereed)
    Abstract [en]

    A brief overview of the development of direct substitution of the hydroxyl (OH) group of alcohols in our research group is presented. By applying a BrOnsted acid, an intramolecular substitution of the OH group in stereogenic alcohols with chirality transfer was achieved. Noteworthy, the intramolecular substitution has a wide scope in respect to both the nucleophile and also the nucleofuge. A mechanistic study by both experiments and DFT calculations revealed a unique reaction pathway in which the BrOnsted acid operates in a bifunctional manner to promote an S(N)2-type reaction mechanism.

  • 4.
    Bunrit, Anon
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Uppsala University, Sweden.
    Sawadjoon, Supaporn
    Tšupova, Svetlana
    Sjöberg, Per J. R.
    Samec, Joseph S. M.
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Uppsala University, Sweden.
    A General Route to beta-Substituted Pyrroles by Transition-Metal Catalysis2016In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 81, no 4, p. 1450-1460Article in journal (Refereed)
    Abstract [en]

    An atom-efficient route to pyrroles substituted in the beta-position has been achieved in four high yielding steps by a combination of Pd, Ru, and Fe catalysis with only water and ethene as side-products. The reaction is general and gives pyrroles substituted in the beta-position with linear and branched alkyl, benzyl, or aryl groups in overall good yields. The synthetic route includes a Pd-catalyzed monoallylation step of amines with substituted allylic alcohols that proceeds to yield the monoallylated products in moderate to excellent yields. In a second step, unsymmetrical diallylated aromatic amines are generated from the reaction of a second allylic alcohol with high selectivity in moderate to good yields by control of the reaction temperature. Ru-catalyzed ring-closing metathesis performed on the diallylated aromatic amines yields the pyrrolines substituted in the beta-position in excellent yields. By addition of ferric chloride to the reaction mixture, a selective aromatization to yield the corresponding pyrroles substituted in the beta-position was achieved. A reaction mechanism involving a palladium hydride, generated from insertion of palladium to O-H of an allyl alcohol, that is responsible for the C-O bond cleavage to generate the pi-allyl intermediate is proposed.

  • 5.
    Bunrit, Anon
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Srifa, Pemikar
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Dahlstrand, Christian
    Huang, Genping
    Biswas, Srijit
    Himo, Fahmi
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Watile, Rahul
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Samec, Joseph
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    H3PO2-Catalyzed Intramolecular Stereospecific Substitution of the Hydroxyl Group in Stereogenic Secondary Alcohols by N-, O-, and S-centered Nucleophiles to Generate HeterocyclesManuscript (preprint) (Other academic)
    Abstract [en]

    The direct intramolecular stereospecific substitution of the hydroxyl group in stereogenic secondary alcohols was successfully accomplished by phosphinic acid catalysis. The hydroxyl group was displaced by O-, S-, and N-centered nucleophiles to provide enantioenriched five- and six-membered heterocycles in good to excellent yields and high enantiospecificity with water as the only by product. Mechanistic studies using both experiments and calculations have been performed. Rate order determination shows first-order dependences in catalyst, internal nucleophile, and electrophile concentrations, however, independence on external nucleophile and electrophile. Furthermore, phosphinic acid does not promote SN1 reactivity. Computational studies support a bifunctional role of the phosphinic acid in which activations of both nucleofuge and nucleophile occur in a bridging SN2-type transition state. 

  • 6.
    Bunrit, Anon
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Watile, Rahul
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Lagerspets, Emi
    Lanekoff, Ingela
    Biswas, Srijit
    Repo, Timo
    Samec, Joseph
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Iron (III)-Catalyzed Intramolecular Stereospecific Substitution of the OH Group in Stereogenic Secondary and Tertiary AlcoholsManuscript (preprint) (Other academic)
    Abstract [en]

    We herein report a Fe(OTf)3-catalyzed stereospecific substitution of the hydroxyl (OH) group in secondary and tertiary alcohols by N-, and O-centered nucleophiles to generate synthetically precious enantioenriched pyrrolidines, tetrahydrofuran, 1,2,3,4-tetra-hydroquinolines, and chromanes. The substitution of the OH group in benzylic, allylic, and aliphatic alcohols proceed with high yields and high degree of enantiospecificity to give saturated five- and six-membered heterocyclic products and water as the only by-product. Mechanistic studies revealed that the intramolecular substitution reaction proceeds through an SN2 reaction with secondary alcohols and an SN1 reaction, comprising a tight ion pair, with tertiary alcohols giving products with inversion of configuration at the stereogenic carbon in both cases. The iron interacts with both nucleofile and nucloefuge, where the latter leads to a controlled carbon−oxygen (C–O) bond cleavage. The procedure opens up new atom efficient technique for catalytic stereospecific reactions that allow easily accessible stereogenic secondary and tertiary alcohols to be considered as substrates in substitution reactions. 

  • 7.
    Di Francesco, Davide
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Subbotina, Elena
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Rautiainen, Sari
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Samec, Joseph S. M.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Ductile Pd-Catalysed Hydrodearomatization of Phenol-Containing Bio-Oils Into Either Ketones or Alcohols using PMHS and H2O as Hydrogen Source2018In: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 360, no 20, p. 3924-3929Article in journal (Refereed)
    Abstract [en]

    A series of phenolic bio-oil components were selectively hydrodearomatized by palladium on carbon into the corresponding ketones or alcohols in excellent yields using polymethylhydrosiloxane and water as reducing agent. The selectivity of the reaction was governed by the water concentration where selectivity to alcohol was favoured at higher water concentrations. As phenolic bio-oil examples cardanol and beech wood tar creosote were studied as substrate to the developed reaction conditions. Cardanol was hydrodearomatized into 3-pentadecylcyclohexanone in excellent yield. From beech wood tar creosote, a mixture of cyclohexanols was produced. No hydrodeoxygenation occurred, suggesting the applicability of the reported method for the production of ketone-alcohol oil from biomass.

  • 8. Francois, Camille
    et al.
    Pourchet, Sylvie
    Boni, Gilles
    Fontaine, Stephane
    Gaillard, Yves
    Placet, Vincent
    Galkin, Maxim V.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Orebom, Alexander
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Samec, Joseph
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Plasseraud, Laurent
    Diglycidylether of iso-eugenol: a suitable lignin-derived synthon for epoxy thermoset applications2016In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 73, p. 68732-68738Article in journal (Refereed)
    Abstract [en]

    A novel lignin-based synthon, diglycidylether of iso-eugenol (DGE-isoEu) is used as a prepolymer for the preparation of thermosetting resins. DGE-isoEu is synthesized in a two-step procedure with a satisfactory yield from bio-based iso-eugenol (isoEu, 2-methoxy-4-(1-propenyl)phenol) catalytically fragmented from lignin in an organosolv process. DGE-isoEu was fully characterized by NMR, MS and FTIR. Curing of the DGE-isoEu monomer has then been investigated in the presence of several carboxylic acid derivatives hardeners. The thermal and mechanical properties of each material were recorded showing, in particular, a high T-g and instantaneous modulus values in the range of 78-120 degrees C and 4.6-5.5 GPa, respectively. The lignin derived new materials give very attractive thermo-mechanical properties comparable to that of common BPA-containing epoxy resins.

  • 9. François, Camille
    et al.
    Pourchet, Sylvie
    Boni, Gilles
    Rautiainen, Sari
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Samec, Joseph
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Fournier, Lucie
    Robert, Carine
    Thomas, Christophe M.
    Fontaine, Stephane
    Gaillard, Yves
    Placet, Vincent
    Plasseraud, Laurent
    Design and synthesis of biobased epoxy thermosets from biorenewable resources2017In: Comptes rendus. Chimie, ISSN 1631-0748, E-ISSN 1878-1543, Vol. 20, no 11-12, p. 1006-1016Article in journal (Refereed)
    Abstract [en]

    Biobased diepoxy synthons derived from isoeugenol, eugenol or resorcinol (DGE-isoEu, DGE-Eu and DGER, respectively) have been used as epoxy monomers in replacement of the diglycidyl ether of bisphenol A (DGEBA). Their curing with six different biobased anhydride hardeners leads to fully biobased epoxy thermosets. These materials exhibit interesting thermal and mechanical properties comparable to those obtained with conventional petrosourced DGEBA-based epoxy resins cured in similar conditions. In particular, a high T-g in the range of 90-130 degrees C and instantaneous moduli higher than 4.3 GPa have been recorded. These good performances are very encouraging, making these new fully biobased epoxy thermosets compatible with the usual structural application of epoxy materials.

  • 10.
    Galkin, Maxim V.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Samec, Joseph S. M.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Lignin Valorization through Catalytic Lignocellulose Fractionation: A Fundamental Platform for the Future Biorefinery2016In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 9, no 13, p. 1544-1558Article, review/survey (Refereed)
    Abstract [en]

    Current processes for the fractionation of lignocellulosic biomass focus on the production of high-quality cellulosic fibers for paper, board, and viscose production. The other fractions that constitute a major part of lignocellulose are treated as waste or used for energy production. The transformation of lignocellulose beyond paper pulp to a commodity (e.g., fine chemicals, polymer precursors, and fuels) is the only feasible alternative to current refining of fossil fuels as a carbon feedstock. Inspired by this challenge, scientists and engineers have developed a plethora of methods for the valorization of biomass. However, most studies have focused on using one single purified component from lignocellulose that is not currently generated by the existing biomass fractionation processes. A lot of effort has been made to develop efficient methods for lignin depolymerization. The step to take this fundamental research to industrial applications is still a major challenge. This review covers an alternative approach, in which the lignin valorization is performed in concert with the pulping process. This enables the fractionation of all components of the lignocellulosic biomass into valorizable streams. Lignocellulose fractions obtained this way (e.g., lignin oil and glucose) can be utilized in a number of existing procedures. The review covers historic, current, and future perspectives, with respect to catalytic lignocellulose fractionation processes.

  • 11.
    Galkin, Maxim V.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Smit, Arjan T.
    Subbotina, Elena
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Artemenko, Konstantin A.
    Bergquist, Jonas
    Huijgen, Wouter J. J.
    Samec, Joseph S. M.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Hydrogen-free catalytic fractionation of woody biomass2016In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 9, no 23, p. 3280-3287Article in journal (Refereed)
    Abstract [en]

    The pulping industry could become a biorefinery if the lignin and hemicellulose components of the lignocellulose are valorized. Conversion of lignin into well-defined aromatic chemicals is still a major challenge. Lignin depolymerization reactions often occur in parallel with irreversible condensation reactions of the formed fragments. Here, we describe a strategy that markedly suppresses the undesired condensation pathways and allows to selectively transform lignin into a few aromatic compounds. Notably, applying this strategy to woody biomass at organosolv pulping conditions, the hemicellulose, cellulose, and lignin were separated and in parallel the lignin was transformed into aromatic monomers. In addition, we were able to utilize a part of the lignocellulose as an internal source of hydrogen for the reductive lignin transformations. We hope that the presented methodology will inspire researchers in the field of lignin valorization as well as pulp producers to develop more efficient biomass fractionation processes in the future.

  • 12.
    Kumaniaev, Ivan
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Samec, Joseph S. M.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Adsorption Isotherms of Lignin-Derived Compounds on a Palladium Catalyst2019In: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 58, no 16, p. 6899-6906Article in journal (Refereed)
    Abstract [en]

    We have studied the interaction of lignin fragments obtained from catalytic fractionation with a heterogeneous palladium catalyst. By studying the adsorption of verified substrate and product molecules on the palladium surface, understanding of what governs adsorption and desorption dynamics of both substrates and products has been obtained. In addition, we have studied the kinetic isotope effect of hydrogen-transfer reactions occurring on the surface of the catalyst. These studies give insights into the thermodynamics of the process in which species from lignin-derived species adsorb to the catalyst surface, are then transformed by hydrogenation-hydrogenolysis reactions in a slow reaction step, and finally desorbed. It was found that the adsorption dynamics depended on the degree of unsaturation as well as the presence of methoxy groups on the aryl. Thereby, the adsorption is stronger for substrate molecules derived from lignin than for reduced molecules obtained after the rate-determining transfer-hydrogenation and hydrogenolysis transformations.

  • 13.
    Kumaniaev, Ivan
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Samec, Joseph S. M.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Valorization of Quercus suber Bark toward Hydrocarbon Bio-Oil and 4-Ethylguaiacol2018In: ACS sustainable chemistry and engineering, ISSN 2168-0485, Vol. 6, no 5, p. 5737-5742Article in journal (Refereed)
    Abstract [en]

    A reductive fractionation process for the valorization of Quercus suber bark toward hydrocarbons in gasoline and diesel ranges and optionally 4-ethylguaiacol has been developed. The procedure involves three steps: (1) tandem hydrogen-free Pd/C-catalyzed transfer hydrogenolysis of lignin where the carbohydrates serve as an inherent hydrogen donor under slightly alkaline conditions to also facilitate the depolymerization of suberin, (2) optional distillation, to isolate the 4-ethylguaiacol, (3) hydrodeoxygenation of the mixture from the first step by a Pt-MoO3/TiO2 catalyst generated hydrocarbons in gasoline and diesel ranges. The yield of 4-ethylguaiacol (90% purity) is 2.6% of dry bark weight (12% of acid insoluble lignin), and yield of hydrocarbon bio-oil is 42% of dry bark weight. This corresponds to a theoretical maximum yield of 77% for lignin and suberin. The carbon yield of the obtained bio-oil is thereby 64% from the total initial bark.

  • 14.
    Kumaniaev, Ivan
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Subbotina, Elena
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sävmarker, Jonas
    Larhed, Mats
    Galkin, Maxim V.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Samec, Joseph S. M.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Lignin depolymerization to monophenolic compounds in a flow-through system2017In: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, Vol. 19, no 24, p. 5767-5771Article in journal (Refereed)
    Abstract [en]

    A reductive lignocellulose fractionation in a flow-through system in which pulping and transfer hydrogenolysis steps were separated in time and space has been developed. Without the hydrogenolysis step or addition of trapping agents to the pulping, it is possible to obtain partially depolymerized lignin (21 wt% monophenolic compounds) that is prone to further processing. By applying a transfer hydrogenolysis step 37 wt% yield of lignin derived monophenolic compounds was obtained. Pulp generated in the process was enzymatically hydrolyzed to glucose in 87 wt% yield without prior purification.

  • 15. Li, Hongji
    et al.
    Subbotina, Elena
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bunrit, Anon
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Dalian Institute of Chemical Physics (DICP), China .
    Wang, Feng
    Samec, Joseph S. M.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Functionalized spirolactones by photoinduced dearomatization of biaryl compounds2019In: Chemical Science, ISSN 2041-6520, E-ISSN 2041-6539, Vol. 10, no 12, p. 3681-3686Article in journal (Refereed)
    Abstract [en]

    The idea of using biaryl structures to generate synthetic building blocks such as spirolactones is attractive because biaryl structures are abundant in biomass waste streams. However, the inertness of aromatic rings of biaryls makes it challenging to transform them into functionalized structures. In this work, we developed photoinduced dearomatization of nonphenolic biaryl compounds to generate spirolactones. We demonstrate that dearomatization can be performed via either aerobic photocatalysis or anaerobic photooxidation to tolerate specific synthetic conditions. In both pathways, dearomatization is induced by electrophilic attack of the carboxyl radical. The resulting spirodiene radical is captured by either oxygen or water in aerobic and anaerobic systems, respectively, to generate the spirodienone. These methods represent novel routes to synthesize spirolactones from the biaryl motif.

  • 16. Margalef, Jessica
    et al.
    Watile, Rahul A.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Rukkijakan, Thanya
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Samec, Joseph S. M.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    High-Atom Economic Approach To Prepare Chiral alpha-Sulfenylated Ketones2019In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 84, no 17, p. 11219-11227Article in journal (Refereed)
    Abstract [en]

    Chiral alpha-sulfenylated ketones are versatile building blocks, although there are still several limitations with their preparation. Here we report a new two-step procedure, consisting of Pd-catalyzed hydrothiolation of propargylic alcohols followed by an enantioselective Rh isomerization of allylic alcohols. The isomerization reaction is the key step for obtaining the ketones in their enantioenriched form. The new methodology has a high atom economy and induces good to high levels of enantioselectivity; no waste is produced. A mechanism involving a Rh-hydride-enone intermediate is proposed for the isomerization reaction.

  • 17. Monti, Susanna
    et al.
    Srifa, Pemikar
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kumaniaev, Ivan
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Samec, Joseph S. M.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    ReaxFF Simulations of Lignin Fragmentation on a Palladium-Based Heterogeneous Catalyst in Methanol-Water Solution2018In: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 9, no 18, p. 5233-5239Article in journal (Refereed)
    Abstract [en]

    The interaction of fragments derived from lignin depolymerization with a heterogeneous palladium catalyst in methanol-water solution is studied by means of experimental and theoretical methodologies. Quantum chemistry calculations and molecular dynamics simulations based on the ReaxFF approach are combined effectively to obtain an atomic level characterization of the crucial steps of the adsorption of the molecules on the catalyst, their fragmentation, reactions, and desorption. The main products are identified, and the most important routes to obtain them are explained through extensive computational procedures. The simulation results are in excellent agreement with the experiments and suggest that the mechanisms comprise a fast chemisorption of identified fragments from lignin on the metal interface accompanied by bond breaking, release of some of their hydrogens and oxygens to the support, and eventual desorption depending on the local environment. The strongest connections are those involving the aromatic rings, as confirmed by the binding energies of selected representative structures, estimated at the quantum chemistry level. The satisfactory agreement with the literature, quantum chemistry data, and experiments confirms the reliability of the multilevel computational procedure to study complex reaction mixtures and its potential application in the design of high-performance catalytic devices.

  • 18. Orebom, Alexander
    et al.
    Verendel, J. Johan
    Samec, Joseph S. M.
    Stockholm University, Faculty of Science, Department of Organic Chemistry. RenFuel AB, Sweden.
    High Yields of Bio Oils from Hydrothermal Processing of Thin Black Liquor without the Use of Catalysts or Capping Agents2018In: ACS omega, ISSN 2470-1343, Vol. 3, no 6, p. 6757-6763Article in journal (Refereed)
    Abstract [en]

    Black liquor (BL) from the kraft pulping process has been treated at elevated temperatures (380 degrees C) in a batch reactor to give high yields of a bio oil comprising monomeric phenolic compounds that were soluble in organic solvents and mineral oil and a water fraction with inorganic salts. The metal content in the product was < 20 ppm after a simple extraction step. A correlation between concentration, temperature, and reaction time with respect to yield of desired product was found. At optimal reaction conditions (treating BL with 16 wt % dry substance at 380 degrees C for 20 min), the yield of extractable organics was around 80% of the original lignin with less than 7% of char. The product was analyzed by gel permeable chromatography, mass spectroscopy, nuclear magnetic resonance, elemental analysis, and inductively coupled plasma. It was found that a large fraction composed of mainly cresols, xylenols, and mesitols. This process provides a pathway to convert a major waste stream from a pulp mill into a refinery feed for fuel or chemical production, whereas at the same time the inorganic chemicals are recovered and can be returned back to the pulp mill.

  • 19.
    Rautiainen, Sari
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Di Francesco, Davide
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Katea, Sarmad Naim
    Westin, Gunnar
    Tungasmita, Duangamol N.
    Samec, Joseph S. M.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Lignin Valorization by Cobalt-Catalyzed Fractionation of Lignocellulose to Yield Monophenolic Compounds2019In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 12, no 2, p. 404-408Article in journal (Refereed)
    Abstract [en]

    Herein, a catalytic reductive fractionation of lignocellulose is presented using a heterogeneous cobalt catalyst and formic acid or formate as a hydrogen donor. The catalytic reductive fractionation of untreated birch wood yields monophenolic compounds in up to 34 wt % yield of total lignin, which corresponds to 76% of the theoretical maximum yield. Model compound studies revealed that the main role of the cobalt catalyst is to stabilize the reactive intermediates formed during the organosolv pulping by transfer hydrogenation and hydrogenolysis reactions. Additionally, the cobalt catalyst is responsible for depolymerization reactions of lignin fragments through transfer hydrogenolysis reactions, which target the beta-O-4' bond. The catalyst could be recycled three times with only negligible decrease in efficiency, showing the robustness of the system.

  • 20.
    Rukkijakan, Thanya
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Akkarasamiyo, Sunisa
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sawadjoon, Supaporn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Samec, Joseph S. M.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Pd-Catalyzed Substitution of the OH Group of Nonderivatized Allylic Alcohols by Phenols2018In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 83, no 7, p. 4099-4104Article in journal (Refereed)
    Abstract [en]

    Nonactivated phenols have been employed as nucleophiles in the allylation of nonderivatized allylic alcohols to generate allylated phenolic ethers with water as the only byproduct. A Pd[BiPhePhos] catalyst was found to be reactive to give the O-allylated phenols in good to excellent yields in the presence of molecular sieves. The reactions are chemo-selective in which the kinetically favored O-allylated products are formed exclusively over the thermodynamically favored C-allylated products.

  • 21. Srifa, Pemikar
    et al.
    Galkin, Maxim V.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Samec, Joseph S. M.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Hermansson, Kersti
    Broqvist, Peter
    Detecting Important Intermediates in Pd Catalyzed Depolymerization of a Lignin Model Compound by a Combination of DFT Calculations and Constrained Minima Hopping2016In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 120, no 41, p. 23469-23479Article in journal (Refereed)
    Abstract [en]

    Density functional theory (DFT) calculations, combined with a constrained minima hopping algorithm (global minimum search while preserving the molecular identity), have been performed to investigate important reaction intermediates for the heterogeneously catalyzed beta-O-4' bond cleavage in lignin derivatives. More specifically, we have studied the adsorption properties of a keto tautomer (1-methoxypropan-2-one) and its enol form on a catalytically active Pd(111) surface. In agreement with experiments, we find that for the gas phase molecules the keto tautomer is the most stable. Interestingly, the enol tautomer has a higher affinity to the Pd catalyst than the keto form, and becomes the most stable molecular form when adsorbed on the catalyst surface. The global minimum complex found on the metal surface corresponds to an enolate structure formed when the enol tautomer chemisorbs onto the surface and donates its pi-electrons from the C=C region to two adjacent palladium atoms. The actual formation of a chemical bond to the surface in the case of the enol molecule could be the key to understanding why the enol derivative is needed for an efficient beta-O-4' bond cleavage.

  • 22.
    Subbotina, Elena
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Galkin, Maxim V.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Samec, Joseph S. M.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Pd/C-Catalyzed Hydrogenolysis of Dibenzodioxocin Lignin Model Compounds Using Silanes and Water as Hydrogen Source2017In: ACS Sustainable Chemistry & Engineering, ISSN 2168-0485, Vol. 5, no 5, p. 3726-3731Article in journal (Refereed)
    Abstract [en]

    A mild Pd/C-catalyzed hydrogenolysis of the C-O bond of model Compounds representing the dibenzodioxocin motif in lignin using polymethylhydrosiloxane (PMHS) and water as hydrogen sources was developed. The efficiency of the reaction is highly dependent on both water Concentration and the addition of a base. The results from mechanistic studies showed that the benzylic C-O bond is cleaved faster than the terminal C-O bond, which only cleaves upon the presence of the neighboring phenol. We propose a hydrogen bond formation between an oxygen atom of an ether group and a proton of a neighboring phenol under the employed mild reaction Conditions, which facilitates cleavage of the C-O bond.

  • 23. Tsupova, Svetlana
    et al.
    Cadu, Alban
    Stuck, Fabian
    Rominger, Frank
    Rudolph, Matthias
    Samec, Joseph S. M.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Hashmi, A. Stephen K.
    Dual Gold(I)-catalyzed Cyclization of Dialkynyl Pyridinium Salts2017In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 9, no 11, p. 1915-1920Article in journal (Refereed)
    Abstract [en]

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

  • 24.
    Watile, Rahul A.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bunrit, Anon
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Margalef, Jèssica
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Akkarasamiyo, Sunisa
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Ayub, Rabia
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Lagerspets, Emi
    Biswas, Srijit
    Repo, Timo
    Samec, Joseph S. M.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Intramolecular substitutions of secondary and tertiary alcohols with chirality transfer by an iron (III) catalyst2019In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 10, article id 3826Article in journal (Refereed)
    Abstract [en]

    Optically pure alcohols are abundant in nature and attractive as feedstock for organic synthesis but challenging for further transformation using atom efficient and sustainable methodologies, particularly when there is a desire to conserve the chirality. Usually, substitution of the OH group of stereogenic alcohols with conservation of chirality requires derivatization as part of a complex, stoichiometric procedure. We herein demonstrate that a simple, inexpensive, and environmentally benign iron(III) catalyst promotes the direct intramolecular substitution of enantiomerically enriched secondary and tertiary alcohols with O-, N-, and S-centered nucleophiles to generate valuable 5-membered, 6-membered and aryl-fused 6-membered heterocyclic compounds with chirality transfer and water as the only byproduct. The power of the methodology is demonstrated in the total synthesis of (+)-lentiginosine from D-glucose where iron-catalysis is used in a key step. Adoption of this methodology will contribute towards the transition to sustainable and bio-based processes in the pharmaceutical and agrochemical industries.

1 - 24 of 24
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