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  • 1. Biosca, Maria
    et al.
    Paptchikhine, Alexander
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Pàmies, Oscar
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Diéguez, Montserrat
    Extending the Substrate Scope of Bicyclic P-Oxazoline/Thiazole Ligands for Ir-Catalyzed Hydrogenation of Unfunctionalized Olefins by Introducing a Biaryl Phosphoroamidite Group2015In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 21, no 8, p. 3455-3464Article in journal (Refereed)
    Abstract [en]

    This study identifies a series of Ir-bicyclic phosphoroamidite-oxazoline/thiazole catalytic systems that can hydrogenate a wide range of minimally functionalized olefins (including E-and Z-tri- and disubstituted substrates, vinylsilanes, enol phosphinates, tri- and disubstituted alkenylboronic esters, and alpha,beta-unsaturated enones) in high enantioselectivities (ee values up to 99%) and conversions. The design of the new phosphoroamidite-oxazoline/thiazole ligands derives from a previous successful generation of bicyclic N-phosphane-oxazoline/thiazole ligands, by replacing the N-phosphane group with a pi-acceptor biaryl phosphoroamidite moiety. A small but structurally important family of Ir-phosphoroamidite-oxazoline/thiazole precatalysts has thus been synthesized by changing the nature of the N-donor group (either oxazoline or thiazole) and the configuration at the biaryl phosphoroamidite moiety. The substitution of the N-phosphane by a phosphoroamidite group in the bicyclic N-phosphane-oxazoline/thiazole ligands extended the range of olefins that can be successfully hydrogenated.

  • 2. Cadu, Alban
    et al.
    Upadhyay, Puspesh K.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry. University of Kwazulu Natal, South Africa.
    Iridium-Catalyzed Asymmetric Hydrogenation of Substituted Pyridines2013In: Asian Journal of Organic Chemistry, ISSN 2193-5807, Vol. 2, no 12, p. 1061-1065Article in journal (Refereed)
    Abstract [en]

    Asymmetric hydrogenation of ortho-substituted pyridines catalyzed by N,P-ligated iridium is demonstrated. To facilitate this reaction, the aromaticity of the pyridines was weakened by forming N-iminopyridium ylides. The reactions give very high conversions, and after a single recrystallization, excellent ee of up to 98% was obtained. This method lends itself to the synthesis of chiral piperidine building blocks.

  • 3.
    Jiang, Tuo
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Quan, Xu
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Zhu, Can
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Palladium-Catalyzed Oxidative Synthesis of a-Acetoxylated Enones from Alkynes2016In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 55, no 19, p. 5824-5828Article in journal (Refereed)
    Abstract [en]

    We report a palladium-catalyzed oxidative functionalization of alkynes to generate -acetoxylated enones in one step. A range of functional groups are well-tolerated in this reaction. Mechanistic studies, including the use of O-18-labeled DMSO, revealed that the ketone oxygen atom in the product originates from DMSO.

  • 4.
    Kerdphon, Sutthichat
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Ponra, Sudipta
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Yang, Jianping
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Wu, Haibo
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Iridium-Catalyzed Enantio- and Diastereoselective Hydrogenation of Acyclic Tetra-Substituted OlefinsManuscript (preprint) (Other academic)
  • 5.
    Kerdphon, Sutthichat
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Xu, Quan
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Parihar, Vijay Singh
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    C-N Coupling of Amides with Alcohols Catalyzed by N-Heterocyclic Carbene-Phosphine Iridium Complexes2015In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 80, no 22, p. 11529-11537Article in journal (Refereed)
    Abstract [en]

    N-heterocyclic carbene-phosphine iridium complexes (NHC-Ir) were developed/found to be a highly reactive catalyst for N-monoalkylation of amides with alcohols via hydrogen transfer. The reaction produced the desired product in high isolated yields using a wide range of substrates with low catalyst loading and short reaction times.

  • 6.
    Krajangsri, Suppachai
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Wu, Haibo
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Liu, Jianguo
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Rabten, Wangchuk
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Andersson, Pher
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Chemoselective Iridium-catalysed Peterson olefination/Asymmetric Hydrogenation of beta-Hydroxy SilanedManuscript (preprint) (Other academic)
    Abstract [en]

    Herein we report the use of Ir-N,P catalysts for the asymmetric hydrogenation of β-hydroxy silanes via an in-situ generated olefin intermediate. The reaction proceeds via an acid catalysed Peterson olefination reaction and provides hydrogenated products in excellent ee’s of up to 99% accompanied with high isolated yields under mild reaction conditions and short reaction times. Modification of the reaction conditions provides a choice to hydrogenate either an olefin or a β-hydroxy silane in a chemo-selective manner leaving the other functionality unaffected in the product.

  • 7.
    Krajangsri, Suppachai
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Yang, Jianping
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Massaro, Luca
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Andersson, Pher
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Iridium-Catalysed Enantioselective Hydrogenation of Enamides2018Manuscript (preprint) (Other academic)
    Abstract [en]

    A variety of oxazolidinone-enamides were prepared and evaluated in this reaction. High yields, (up to 99%) and excellent ee, (up to 99%) were obtained.

  • 8. Li, Jia-Qi
    et al.
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry. University of KwaZulu-Natal, South Africa.
    Room temperature and solvent-free iridium-catalyzed selective alkylation of anilines with alcohols2013In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 49, no 55, p. 6131-6133Article in journal (Refereed)
    Abstract [en]

    A bidentate iridium NHC-phosphine complex has been developed and applied to the N-monoalkylation of aromatic amines with a wide range of primary alcohols and to the N-heterocyclization of amino alcohols. This reaction resulted in high isolated product yields, even at room temperature and under solvent-free conditions.

  • 9. Li, Jia-Qi
    et al.
    Liu, Jianguo
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Krajangsri, Suppachai
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Chumnanvej, Napasawan
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Singh, Thishana
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Asymmetric Hydrogenation of Allylic Alcohols Using Ir-N,P-Complexes2016In: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 6, no 12, p. 8342-8349Article in journal (Refereed)
    Abstract [en]

    In this study, a series of gamma,gamma-disubstituted and beta,gamma-disubstituted allylic alcohols were prepared and successfully hydrogenated using suitable N,P-based Ir complexes. High yields and excellent enantioselectivities were obtained for most of the substrates studied. This investigation also revealed the effect of the acidity of the N,P-Ir-complexes on the acid sensitive allylic alcohols. DFT Delta pK(a) calculations were used to explain the effect of the N,P-ligand on the acidity of the corresponding Ir-complex. The selectivity model of the reaction was used to accurately predict the absolute configuration of the hydrogenated alcohols.

  • 10.
    Li, Jia-Qi
    et al.
    Uppsala University, Sweden.
    Peters, Byron
    Uppsala University, Sweden.
    Andersson, Pher G.
    Uppsala University, Sweden; University of KwaZulu-Natal, South Africa.
    Highly Enantioselective Asymmetric Isomerization of Primary AllylicAlcohols with an Iridium–N,P Complex2011In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 17, p. 11143-11145Article in journal (Refereed)
    Abstract [en]

    Highly enantioselective asym. isomerization of a range of E- and Z- trisubstituted primary allylic alcs. to the corresponding chiral aldehydes catalyzed by a N,​P-​ligated iridium complex is reported.  Notably, the selectivity of this catalyst was less sensitive to steric effects in the asym. isomerization of Z-​trisubstituted allylic alcs. than E-​trisubstituted compds.

  • 11.
    Li, Jia-Qi
    et al.
    Uppsala University, Sweden.
    Xu, Quan
    Uppsala University, Sweden.
    Andersson, Pher
    Uppsala University, Sweden; University Of KwaZulu-Natal, South Africa.
    Highly Enantioselective Iridium Catalyzed Hydrogenation of α, β-Unsaturated Esters2012In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 18, no 34, p. 10609-10616Article in journal (Refereed)
    Abstract [en]

    α,β-Unsaturated esters have been employed as substrates in iridium-catalyzed asymmetric hydrogenation. Full conversions and good to excellent enantioselectivities (up to 99 % ee) were obtained for a broad range of substrates with both aromatic- and aliphatic substituents on the prochiral carbon. The hydrogenated products are highly useful as building blocks in the synthesis of a variety of natural products and pharmaceuticals.

  • 12.
    Liu, Jianguo
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Krajangsri, Suppachai
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Li, Jiaqi
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Iridium-catalyzed Asymmetric Hydrogenation of Allylic Alcohols via Dynamic Kinetic ResolutionManuscript (preprint) (Other academic)
  • 13.
    Liu, Jianguo
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Krajangsri, Suppachai
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Singh, Thishana
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    De Seriis, Giulia
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Chumnanvej, Napasawan
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Wu, Haibo
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Regioselective Iridium-Catalyzed Asymmetric Monohydrogenation of 1,4-Dienes2017In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 139, no 41, p. 14470-14475Article in journal (Refereed)
    Abstract [en]

    A highly efficient regio- and enantioselective monohydrogenation of 1,4-dienes has been realized using an iridium catalyst with a chiral N,P-ligand under mild conditions. The substrate scope was studied and included both unfunctionalized as well as functionalized substituents on the meta- or para-position. Substrates having substituents with functionalities such as silyl protected alcohols or ketals were monohydrogenated in high regioselectivity and high enantiomeric excess (up to 98% ee).

  • 14.
    Lui, Jianguo
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Krajangsri, Suppachai
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Yang, Jianping
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Li, Jia-Qi
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Andersson, Pher
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Iridium-catalysed asymmetric hydrogenation of allylic alcohols via dynamic kinetic resolutionIn: Article in journal (Refereed)
    Abstract [en]

    Dynamic kinetic resolutions (DKRs) allow for the conversion of both enantiomers of starting material into a single enantiomer  of product, hence avoiding the 50% yield limit observed in traditional kinetic resolutions. Transition-metal-catalysed variants have become an important and useful method in asymmetric synthesis. Here we report an asymmetric hydrogenation of allylic alcohols using an Ir–N,P-ligand complex via DKR. In contrast to the many DKRs involving carbonyl reduction, this methodology allows for DKR during alkene reduction. Mechanistic studies support the hypothesis that racemization of the substrate is achieved by cleavage and reforming of the oxygen–carbon bond. Under the cooperative dynamic kinetic asymmetric hydrogenation, a broad range of chiral alcohols containing two stereogenic centres were produced with excellent diastereoselectivities (up to 95:5) and enantioselectivities (up to 99%).

  • 15.
    Margarita, Cristiana
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Evolution and Prospects of the Asymmetric Hydrogenation of Unfunctionalized Olefins2017In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 139, no 4, p. 1346-1356Article in journal (Refereed)
    Abstract [en]

    The catalytic enantioselective hydrogenation of prochiral olefins is a key reaction in asymmetric synthesis. Its relevance applies to both industry and academia as an inherently direct and sustainable strategy to induce chirality. Here we briefly recount the early breakthroughs concerning the asymmetric hydrogenation of largely unfunctionalized olefins, from the first reports to the advent of chiral Crabtree-like catalysts. The mechanism and its implications on the enantioselectivity are shortly discussed. The main focus of this Perspective lies on the more recent advances in the field, such as the latest developed classes of ligands and the opportunity to employ more Earth-abundant metals. Therefore, separate sections consider iridium N,P-, NHC-, P,S-, and O,P catalysts, and rhodium, palladium, cobalt, and iron catalysts. Finally, the remaining unsolved challenges are examined, and the potential directions of forthcoming research are outlined.

  • 16. Mbunde, Mourice Victor Nyangabo
    et al.
    Innocent, Ester
    Mabiki, Faith
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Ethnobotanical survey and toxicity evaluation of medicinal plants used for fungal remedy in the Southern Highlands of Tanzania2017In: Journal of Intercultural Ethnopharmacology, ISSN 2146-8397, Vol. 6, no 1, p. 84-96Article in journal (Refereed)
    Abstract [en]

    Background/Aim: Some of the antifungal drugs used in the current treatments regime are responding to antimicrobial resistance. In rural areas of Southern Tanzania, indigenous people use antifungal drugs alone or together with medicinal plants to curb the effects of antibiotic resistance. This study documented ethnobotanical information of medicinal plants used for managing fungal infections in the Southern Highlands of Tanzania and further assess their safety. Materials and Methods: Ethnobotanical survey was conducted in Makete and Mufindi districts between July 2014 and December 2015 using semi-structured questionnaires followed by two focus group discussions to verify respondents' information. Cytotoxicity study was conducted on extracts of collected plants using brine shrimp lethality test and analyzed by MS Excel 2013 program. Results: During this survey about 46 plant species belonging to 28 families of angiosperms were reported to be traditionally useful in managing fungal and other health conditions. Among these, Terminalia sericea, Aloe nutii, Aloe lateritia, Zanthoxylum chalybeum, Zanthoxylum deremense, and Kigelia africana were frequently mentioned to be used for managing fungal infections. The preparation of these herbals was mostly by boiling plant parts especially the leaves and roots. Cytotoxicity study revealed that most of the plants tested were nontoxic with LC50 > 100 which implies that most compounds from these plants are safe for therapeutic use. The dichloromethane extract of Croton macrostachyus recorded the highest with LC50 value 12.94 mu g/ml. The ethnobotanical survey correlated well with documented literature from elsewhere about the bioactivity of most plants. Conclusions: The ethnobotanical survey has revealed that traditional healers are rich of knowledge to build on for therapeutic studies. Most of the plants are safe for use; and thus can be considered for further studies on drug discovery.

  • 17. Olsen, Esben P. K.
    et al.
    Singh, Thishana
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Uppsala University, Sweden.
    Harris, Pernille
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Madsen, Robert
    Experimental and Theoretical Mechanistic Investigation of the Iridium-Catalyzed Dehydrogenative Decarbonylation of Primary Alcohols2015In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 137, no 2, p. 834-842Article in journal (Refereed)
    Abstract [en]

    The mechanism for the iridium-BINAP catalyzed dehydrogenative decarbonylation of primary alcohols with the liberation of molecular hydrogen and carbon monoxide was studied experimentally and computationally. The reaction takes place by tandem catalysis through two catalytic cycles involving dehydrogenation of the alcohol and decarbonylation of the resulting aldehyde. The square planar complex IrCl(CO)(rac-BINAP) was isolated from the reaction between [Ir(cod)Cl](2), rac-BINAP, and benzyl alcohol. The complex was catalytically active and applied in the study of the individual steps in the catalytic cycles. One carbon monoxide ligand was shown to remain coordinated to iridium throughout the reaction, and release of carbon monoxide was suggested to occur from a dicarbonyl complex. IrH2Cl(CO)(rac-BINAP) was also synthesized and detected in the dehydrogenation of benzyl alcohol. In the same experiment, IrHCl2(CO)(rac-BINAP) was detected from the release of HCl in the dehydrogenation and subsequent reaction with IrCl(CO)(rac-BINAP). This indicated a substitution of chloride with the alcohol to form a square planar iridium alkoxo complex that could undergo a beta-hydride elimination. A KIE of 1.0 was determined for the decarbonylation and 1.42 for the overall reaction. Electron rich benzyl alcohols were converted faster than electron poor alcohols, but no electronic effect was found when comparing aldehydes of different electronic character. The lack of electronic and kinetic isotope effects implies a rate-determining phosphine dissociation for the decarbonylation of aldehydes.

  • 18.
    Peters, Byron K.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Liu, Jianguo
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Margarita, Cristiana
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Formal Total Synthesis of Aliskiren2015In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 21, no 19, p. 7292-7296Article in journal (Refereed)
    Abstract [en]

    The efficient and selective formal total synthesis of aliskiren is described. Aliskiren, a renin inhibitor drug, has received considerable attention, primarily because it is the first of the renin inhibitor drugs to be approved by the FDA. Herein, the formal synthesis of aliskiren by iridium-catalyzed asymmetric hydrogenation of two allylic alcohol fragments is reported. Screening a number of N,P-ligated iridium catalysts yielded two catalysts that gave the highest enantioselectivity in the hydrogenation, which gave the saturated alcohols in 97 and 93% ee. In only four steps after hydrogenation, the fragments were combined by using the Julia-Kocienski reaction to produce late-stage intermediate in an overall yield of 18%.

  • 19.
    Peters, Byron K.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Liu, Jianguo
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Margarita, Cristiana
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Rabten, Wangchuk
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kerdphon, Sutthichat
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Orebom, Alexander
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Morsch, Thomas
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Enantio- and Regioselective Ir-Catalyzed Hydrogenation of Di- and Trisubstituted Cycloalkenes2016In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 138, no 36, p. 11930-11935Article in journal (Refereed)
    Abstract [en]

    A number of cyclic olefins Were prepared and evaluated for the asymmetric hydrogenation reaction using novel N,P-ligated iridium imidazote-based Catalysts (Crabtree type). The diversity of these cyclic olefins spanned those having little functionality to others bearing strongly coordinating substituents and heterocycles. Excellent enantioselectivities were observed both for substrates having little functionality (up to >99% ee) and for substrates possessing functional groups several carbons away from the olefin. Substrates having functionalities such as carboxyl groups, alcohols, or heterocycles in the vicinity of the C=C bond were hydrogenated in high enantiomeric excess (up to >99% ee). The hydrogenation was also found to be regioselective, and by controlling the reaction conditions, selective hydrogenation of one of two trisubstituted olefins can be achieved: Furthermore, trisubstituted olefins can be selectively hydrogenated in the presence of tetrasubstituted olefins.

  • 20.
    Peters, Byron K.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Liu, Jianguo
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Margarita, Cristiana
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Rabten, Wangchuk
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kerdphon, Sutthichat
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Paptchikhine, Alexander
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Andersson, Pher
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Enantio- and Regioselective Hydrogenation of Minimally and Densely Decorated Unsaturated CarbocyclesManuscript (preprint) (Other academic)
    Abstract [en]

    Several cyclic prochiral olefins were successfully hydrogenated (>99 conv.,up to >99 % ee) using N,P-ligated iridium catalysts. Minimally functionalisedsubstrates (Class 1) were hydrogenated rapidly and in high ee, whichwas consistent with earlier reports. Substrates having functional groups(Class 2) and heterocycles (Class 3) attached to the unsaturated cycle, were43hydrogenated gradually over a period of time, however, high enantioselectivitywas still maintained (up to >99 % ee). This methodology is a highly practical,general and selective means of preparing chiral cyclohexanes.

  • 21.
    Peters, Byron K.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Zhou, Taigang
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Rujirawanich, Janjira
    Cadu, Alban
    Singh, Thishana
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Uppsala University, Sweden.
    Rabten, Wangchuk
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kerdphon, Sutthichat
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    An Enantioselective Approach to the Preparation of Chiral Sulfones by Ir-Catalyzed Asymmetric Hydrogenation2014In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 136, no 47, p. 16557-16562Article in journal (Refereed)
    Abstract [en]

    Several chiral sulfonyl compounds were prepared using the iridium catalyzed asymmetric hydrogenation reaction. Vinylic, allylic and homoallylic sulfone substitutions were investigated, and high enantioselectivity is maintained regardless of the location of the olefin with respect to the sulfone. Impressive stereoselectivity was obtained for dialkyl substitutions, which typically are challenging substrates in the hydrogenation. As expected, the more bulky Z-substrates were hydrogenated slower than the corresponding E isomers, and in slightly lower enantioselectivity.

  • 22.
    Quan, Xu
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Liu, Jianguo
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Rabten, Wangchuk
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Diomedi, Simone
    Singh, Thishana
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Thiazole, Imidazole and Oxazoline Based N,P-Ligands for Palladium-Catalyzed Cycloisomerization of 1,6-Enynes2016In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 20, p. 3427-3433Article in journal (Refereed)
    Abstract [en]

    A series of N,P-ligands were prepared and evaluated in the asymmetric palladium-catalyzed cycloisomerization of allyl propargyl ether substrates. The reactivity and enantioselectivity of the reaction was shown to be highly dependent on the chiral skeleton of the ligand structures with ee's ranging from 22-99 %. The proton source had a significant impact on the enantioselectivity. The generation of palladium hydride from formic acid led to the highest ee. A selectivity model based on a proposed transition state was used to predict and explain the enantiomeric outcome of the reaction.

  • 23.
    Quan, Xu
    et al.
    Uppsala University, Sweden.
    Parihar, Vijay Singh
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bera, Milan
    University of KwaZulu-Natal, South Africa.
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry. University of KwaZulu-Natal, South Africa.
    Iridium Catalysts with Chiral Bicyclic Pyridine-Phosphane Ligands for the Asymmetric Hydrogenation of Olefins2014In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, Vol. 2014, no 1, p. 140-146Article in journal (Refereed)
    Abstract [en]

    New bicyclic pyridine-phosphane ligands were prepared, and their iridium complexes were evaluated in asymmetric hydrogenation of trisubstituted olefins with non-coordinating and weakly coordinating substituents. The iridium catalysts showed high reactivity and enantioselectivity for both types of olefins.

  • 24.
    Rabten, Wangchuk
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kärkäs, Markus D.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Åkermark, Torbjörn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Chen, Hong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Liao, Rong-Zhen
    Tinnis, Fredrik
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sun, Junliang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Siegbahn, Per E. M.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Åkermark, Björn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Catalytic Water Oxidation by a Molecular Ruthenium Complex: Unexpected Generation of a Single-Site Water Oxidation Catalyst2015In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 54, no 10, p. 4611-4620Article in journal (Refereed)
    Abstract [en]

    The increasing energy demand calls for the development of sustainable energy conversion processes. Here, the splitting of H2O to O-2 and H-2, or related fuels, constitutes an excellent example of solar-to-fuel conversion schemes. The critical component in such schemes has proven to be the catalyst responsible for mediating the four-electron oxidation of H2O to O-2. Herein, we report on the unexpected formation of a single-site Ru complex from a ligand envisioned to accommodate two metal centers. Surprising N-N bond cleavage of the designed dinuclear ligand during metal complexation resulted in a single-site Ru complex carrying a carboxylate amide motif. This ligand lowered the redox potential of the Ru complex sufficiently to permit H2O oxidation to be carried out by the mild one-electron oxidant [Ru(bpy)(3)](3+) (bpy = 2,2'-bipyridine). The work thus highlights that strongly electron-donating ligands are important elements in the design of novel, efficient H2O :oxidation catalysts.

  • 25.
    Rabten, Wangchuk
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Margarita, Margarita
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Eriksson, Lars
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Ir-Catalyzed Asymmetric and Regioselective Hydrogenation of Cyclic Allylsilanes and Generation of Quaternary Stereocenters via the Hosomi-Sakurai Allylation2018In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 24, no 7, p. 1681-1685Article in journal (Refereed)
    Abstract [en]

    A number of cyclic dienes containing the allylsilane moiety were prepared via Birch reduction and subjected to iridium-catalyzed regioselective and asymmetric hydrogenation, which provided chiral allylsilanes in high conversion and enantiomeric excess (up to 99 % ee). The compounds were successively used in the Hosomi-Sakurai allylation with various aldehydes employing TiCl4 as Lewis acid, providing adducts with two additional stereogenic centers in excellent diastereoselectivity.

  • 26.
    Rabten, Wangchuk
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Ponra, Sudipta
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kerdphon, Sutthichat
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Wu, Haibo
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    N,P-Iridium Catalyzed Asymmetric Hydrogenation of Vinyl FluoridesManuscript (preprint) (Other academic)
  • 27.
    Rabten, Wangchuk
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Åkermark, Torbjörn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kärkäs, Markus D.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Chen, Hong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). China University of Geosciences, China.
    Sun, Junliang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Peking University, China.
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Åkermark, Björn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    A ruthenium water oxidation catalyst based on a carboxamide ligand2016In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 45, no 8, p. 3272-3276Article in journal (Refereed)
    Abstract [en]

    Herein is presented a single-site Ru complex bearing a carboxamide-based ligand that efficiently manages to carry out the fourelectron oxidation of H2O. The incorporation of the negatively charged ligand framework significantly lowered the redox potentials of the Ru complex, allowing H2O oxidation to be driven by the mild oxidant [Ru(bpy)(3)](3+). This work highlights that the inclusion of amide moieties into metal complexes thus offers access to highly active H2O oxidation catalysts.

  • 28.
    Sayers, Judy
    et al.
    Stockholm University, Faculty of Science, Department of Mathematics and Science Education.
    Andrews, Paul
    Stockholm University, Faculty of Science, Department of Mathematics and Science Education.
    Developing and trialling a simple-to-use instrument for surveying teacher education students’ mathematics-related beliefs2016In: MAVI 22 Proceedings of the MAVI 22 / [ed] Palmer, Skott, 2016, Vol. 22Conference paper (Refereed)
    Abstract [en]

    Acknowledging that what teachers believe informs how they teach we argue the importance of understanding, at both entry and exit, teacher education students’ beliefs about mathematics, mathematics teaching and themselves as learners of mathematics. In this paper we report on the development and trial of a simple to use online survey instrument focused on uncovering teacher education students’ mathematics-related beliefs. Twenty items, targeted on a range of constructs reported in the literature, were set against five point Likert scales. The instrument was found to be reliable and an exploratory factor analysis yielded seven interpretable belief dimensions. The interactions of these dimensions allude to groups of student likely to prove problematic during their programme.

  • 29.
    Shatskiy, Andrey
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Lomoth, Reiner
    Abdel-Magied, Ahmed F.
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Nuclear Materials Authority, Egypt.
    Rabten, Wangchuk
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Laine, Tanja M.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Chen, Hong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). KTH Royal Institute of Technology, Sweden.
    Sun, Junliang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kärkäs, Markus D.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Johnston, Eric V.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Åkermark, Björn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Catalyst-solvent interactions in a dinuclear Ru-based water oxidation catalyst2016In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 45, no 47, p. 19024-19033Article in journal (Refereed)
    Abstract [en]

    Photocatalytic water oxidation represents a key process in conversion of solar energy into fuels and can be facilitated by the use of molecular transition metal-based catalysts. A novel straightforward approach for covalent linking of the catalytic units to other moieties is demonstrated by preparation of a dinuclear complex containing two [Ru(pdc)(pic)(3)]-derived units (pdc = 2,6-pyridinedicarboxylate, pic = 4-picoline). The activity of this complex towards chemical and photochemical oxidation of water was evaluated and a detailed insight is given into the interactions between the catalyst and acetonitrile, a common co-solvent employed to increase solubility of water oxidation catalysts. The solvent-induced transformations were studied by electrochemical and spectroscopic techniques and the relevant quantitative parameters were extracted.

  • 30. Tutkowski, Brandon
    et al.
    Kerdphon, Sutthichat
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Limé, Elaine
    Helquist, Paul
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Wiest, Olaf
    Norrby, Per-Ola
    Revisiting the Stereodetermining Step in Enantioselective Iridium-Catalyzed Imine Hydrogenation2018In: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 8, no 1, p. 615-623Article in journal (Refereed)
    Abstract [en]

    The mechanism for the iridium-catalyzed asymmetric hydrogenation of prochiral imines has been investigated for an experimentally relevant ligand substrate combination using DFT calculations. The possible stereoisomers of the stereodetermining hydride transfer transition state were considered for four possible hydrogenation mechanisms starting from the recently disclosed active catalyst consisting of iridium phosphine-oxazoline with cyclometalated imine substrate. The hydrogenation was found to proceed via an outer sphere pathway. The transition state accurately describes the experimental observations of the active catalyst and provides a structural rationale for the high stereoinduction despite the lack of direct interaction points in the outer-sphere mechanism. The predicted enantioselectivity was consistent with experimental observations. Experimental studies support the hypothesis that the iridacycle forms spontaneously and functions as the active catalyst in the hydrogenation.

  • 31.
    Verendel, J. Johan
    et al.
    Uppsala University, Sweden.
    Li, Jia-Qi
    Uppsala University, Sweden.
    Xu, Quan
    Uppsala University, Sweden.
    Peters, Byron
    Uppsala University, Sweden.
    Zhou, Taigang
    Uppsala University, Sweden.
    Gautun, Odd R.
    Norwegian University of Science and Technology (NTNU), Norway.
    Govender, Thavendran
    University of KwaZulu-Natal, South Africa.
    Andersson, Pher G.
    Uppsala University, Sweden; University of KwaZulu-Natal, South Africa.
    Chiral Hetero- and Carbocyclic Compounds from the Asymmetric Hydrogenation of Cyclic Alkenes2012In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 18, no 21, p. 6507-6513Article in journal (Refereed)
    Abstract [en]

    Several types of chiral hetero- and carbocyclic compounds have been synthesized by using the asymmetric hydrogenation of cyclic alkenes. N,P-Ligated iridium catalysts reduced six-membered cyclic alkenes with various substituents and heterofunctionality in good to excellent enantioselectivity, whereas the reduction of five-membered cyclic alkenes was generally less selective, giving modest enantiomeric excesses. The stereoselectivity of the hydrogenation depended more strongly on the substrate structure for the five- rather than the six-membered cyclic alkenes. The major enantiomer formed in the reduction of six-membered alkenes could be predicted from a selectivity model and isomeric alkenes had complementary enantioselectivity, giving opposite optical isomers upon hydrogenation. The utility of the reaction was demonstrated by using it as a key step in the preparation of chiral 1,3-cis-cyclohexane carboxylates.

  • 32. Verendel, J. Johan
    et al.
    Nordlund, Michael
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Selective Metal-Catalyzed Transfer of H2 and CO from Polyols to Alkenes2013In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 6, no 3, p. 426-429Article in journal (Refereed)
  • 33. Verendel, J. Johan
    et al.
    Pamies, Oscar
    Dieguez, Montserrat
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Univ KwaZulu Natal, Sch Chem, Durban, South Africa.
    Asymmetric Hydrogenation of Olefins Using Chiral Crabtree-type Catalysts: Scope and Limitations2014In: Chemical Reviews, ISSN 0009-2665, E-ISSN 1520-6890, Vol. 114, no 4, p. 2130-2169Article, review/survey (Refereed)
  • 34.
    Xu, Quan
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kerdphon, Sutthichat
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    C-C Coupling of Ketones with Methanol Catalyzed by a N-Heterocyclic Carbene-Phosphine Iridium Complex2015In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 21, p. 3576-3579Article in journal (Refereed)
    Abstract [en]

    An N-heterocyclic carbene–phosphine iridium complex system was found to be a very efficient catalyst for the methylation of ketone via a hydrogen transfer reaction. Mild conditions together with low catalyst loading (1 mol %) were used for a tandem process which involves the dehydrogenation of methanol, CC bond formation with a ketone, and hydrogenation of the new generated double bond by iridium hydride to give the alkylated product. Using this iridium catalyst system, a number of branched ketones were synthesized with good to excellent conversions and yields.

  • 35.
    Xu, Quan
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kerdphon, Sutthichat
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Rujirawanich, Janjira
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Krajangsri, Suppachai
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Andersson, Pher
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Highly Active Cationic NHC, Phosphine Iridium Catalysts for Base Free Asymmetric Hydrogenation of KetonesManuscript (preprint) (Other academic)
  • 36. Yotapan, Nattawut
    et al.
    Paptchikhine, Alexander
    Bera, Milan
    Avula, Satya Kumar
    Vilaivan, Tirayut
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry. University of Kwazulu Natal, South Africa.
    Simple Proline-Derived Phosphine-Thiazole Iridium Complexes for Asymmetric Hydrogenation of Trisubstituted Olefins2013In: Asian Journal of Organic Chemistry, ISSN 2193-5807, Vol. 2, no 8, p. 674-680Article in journal (Refereed)
    Abstract [en]

    Proline-based phosphine-thiazole/imidazole ligands have been synthesized and successfully applied in the homogeneous, iridium-catalyzed, asymmetric hydrogenation of trisubstituted functionalized and unfunctionalized olefins. Five different sets of ligands were prepared then evaluated for their catalytic activity and enantioselectivity in asymmetric hydrogenation.

  • 37.
    Zhou, Taigang
    et al.
    Uppsala University, Sweden.
    Peters, Byron
    Uppsala University, Sweden.
    Maldonado, Matias F.
    Uppsala University, Sweden.
    Govender, Thavendran
    University of KwaZulu-Natal, South Africa.
    Andersson, Pher G.
    Uppsala University, Sweden; University of KwaZulu-Natal, South Africa.
    Enantioselective Synthesis of Chiral Sulfones by Ir-Catalyzed Asymmetric Hydrogenation: A Facile Approach to the Preparation of Chiral Allylic and Homoallylic Compounds2012In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 134, no 33, p. 13592-13595Article in journal (Refereed)
    Abstract [en]

    A highly efficient and enantioselective Ir-catalyzed hydrogenation of unsaturated sulfones was developed. Chiral cyclic and acyclic sulfones were produced in excellent enantioselectivities (up to 98% ee). Coupled with the Ramberg–Bäcklund rearrangement, this reaction offers a novel route to chiral allylic and homoallylic compounds in excellent enantioselectivities (up to 97% ee) and high yields (up to 94%).

1 - 37 of 37
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