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  • 1. Betterley, Nolan M.
    et al.
    Kerdphon, Sutthichat
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Chaturonrutsamee, Suppisak
    Kongsriprapan, Sopanat
    Surawatanawong, Panida
    Soorukram, Darunee
    Pohmakotr, Manat
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Reutrakul, Vichai
    Kuhakarn, Chutima
    Bi(OTf)(3) Enabled C-F Bond Cleavage in HFIP: Electrophilic Aromatic Formylation with Difluoro(phenylsulfanyl)methane2018Inngår i: Asian Journal of Organic Chemistry, ISSN 2193-5807, Vol. 7, nr 8, s. 1642-1647Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Bismuth(III) trifluoromethanesulfonate [Bi(OTf)(3)] mediated mild electrophilic aromatic formylation utilizing difluoro(phenylsulfanyl)methane (PhSCF2H) as a formylating agent in hexafluoro-2-propanol (HFIP) as a recyclable ionizing solvent has been developed. The active formylating species was generated via C-F bond cleavage and was characterized to be a bis(phenylsulfanyl)methyl cation by experimental and computational H-1 and C-13 NMR.

  • 2. Biosca, Maria
    et al.
    Paptchikhine, Alexander
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Pàmies, Oscar
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Diéguez, Montserrat
    Extending the Substrate Scope of Bicyclic P-Oxazoline/Thiazole Ligands for Ir-Catalyzed Hydrogenation of Unfunctionalized Olefins by Introducing a Biaryl Phosphoroamidite Group2015Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 21, nr 8, s. 3455-3464Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 3. Cadu, Alban
    et al.
    Upadhyay, Puspesh K.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. University of Kwazulu Natal, South Africa.
    Iridium-Catalyzed Asymmetric Hydrogenation of Substituted Pyridines2013Inngår i: Asian Journal of Organic Chemistry, ISSN 2193-5807, Vol. 2, nr 12, s. 1061-1065Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 4.
    Jiang, Tuo
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Quan, Xu
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Zhu, Can
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Palladium-Catalyzed Oxidative Synthesis of a-Acetoxylated Enones from Alkynes2016Inngår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 55, nr 19, s. 5824-5828Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 5.
    Kerdphon, Sutthichat
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ponra, Sudipta
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Yang, Jianping
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Wu, Haibo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Iridium-Catalyzed Enantio- and Diastereoselective Hydrogenation of Acyclic Tetra-Substituted OlefinsManuskript (preprint) (Annet vitenskapelig)
  • 6.
    Kerdphon, Sutthichat
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ponra, Sudipta
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Yang, Jianping
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Wu, Haibo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Eriksson, Lars
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. University of KwaZulu-Natal, South Africa.
    Diastereo- and Enantioselective Synthesis of Structurally Diverse Succinate, Butyrolactone, and Trifluoromethyl Derivatives by Iridium-Catalyzed Hydrogenation of Tetrasubstituted Olefins2019Inngår i: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 9, nr 7, s. 6169-6176Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A highly efficient iridium N,P-ligand-catalyzed asymmetric hydrogenation of functionalized tetrasubstituted olefins lacking a directing group has been developed. Various structural diverse chiral succinate derivatives were obtained in high yields and excellent enantio- and diastereoselectivities (up to 99% ee) using 0.5-1.0 mol % catalyst loadings. This stereoselective reaction is applicable for the synthesis of chiral acyclic molecules (up to >99% ee) having two contiguous stereogenic centers and is compatible with various aromatic, aliphatic, and heterocyclic systems, a variety of functional groups of different electronic nature. Furthermore, this asymmetric protocol allows a short enantioselective route to the butyrolactone building block, an intermediate in the synthesis of anticancer agent BMS-871 and pharmaceuticals (2S)-(-)-Verapamil and (2S)-(-)-Gallopamil.

  • 7.
    Kerdphon, Sutthichat
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Xu, Quan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Parihar, Vijay Singh
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    C-N Coupling of Amides with Alcohols Catalyzed by N-Heterocyclic Carbene-Phosphine Iridium Complexes2015Inngår i: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 80, nr 22, s. 11529-11537Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 8.
    Krajangsri, Suppachai
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Wu, Haibo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Liu, Jianguo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Rabten, Wangchuk
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Andersson, Pher
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Chemoselective Iridium-catalysed Peterson olefination/Asymmetric Hydrogenation of beta-Hydroxy SilanedManuskript (preprint) (Annet vitenskapelig)
    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.

  • 9.
    Krajangsri, Suppachai
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Wu, Haibo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Liu, Jianguo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Rabten, Wangchuk
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Singh, Thishana
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. University of Kwazulu-Natal, South Africa.
    Tandem Peterson olefination and chemoselective asymmetric hydrogenation of -hydroxy silanes2019Inngår i: Chemical Science, ISSN 2041-6520, E-ISSN 2041-6539, Vol. 10, nr 12, s. 3649-3653Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Here, we report the first Ir-N,P complex catalyzed tandem Peterson olefination and asymmetric hydrogenation of -hydroxy silanes. This reaction resulted in the formation of chiral alkanes in high isolated yields (up to 99%) and excellent enantioselectivity (up to 99% ee) under mild conditions. Modification of the reaction conditions provides a choice to transform either an olefin or the -hydroxy silane in a chemoselective manner. Additionally, based on this method, an expedient enantioselective synthesis of (S)-(+)--curcumene, from a simple ketone, was accomplished in two steps with 75% overall yield and 95% ee.

  • 10.
    Krajangsri, Suppachai
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Yang, Jianping
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Massaro, Luca
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Andersson, Pher
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Iridium-Catalysed Enantioselective Hydrogenation of EnamidesManuskript (preprint) (Annet vitenskapelig)
    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.

  • 11. Li, Jia-Qi
    et al.
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. University of KwaZulu-Natal, South Africa.
    Room temperature and solvent-free iridium-catalyzed selective alkylation of anilines with alcohols2013Inngår i: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 49, nr 55, s. 6131-6133Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 12. Li, Jia-Qi
    et al.
    Liu, Jianguo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Krajangsri, Suppachai
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Chumnanvej, Napasawan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Singh, Thishana
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Asymmetric Hydrogenation of Allylic Alcohols Using Ir-N,P-Complexes2016Inngår i: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 6, nr 12, s. 8342-8349Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 13.
    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 Complex2011Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 17, s. 11143-11145Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 14.
    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 Esters2012Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 18, nr 34, s. 10609-10616Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 15.
    Liu, Jianguo
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Krajangsri, Suppachai
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Li, Jiaqi
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Iridium-catalyzed Asymmetric Hydrogenation of Allylic Alcohols via Dynamic Kinetic ResolutionManuskript (preprint) (Annet vitenskapelig)
  • 16.
    Liu, Jianguo
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Krajangsri, Suppachai
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Singh, Thishana
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    De Seriis, Giulia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Chumnanvej, Napasawan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Wu, Haibo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Regioselective Iridium-Catalyzed Asymmetric Monohydrogenation of 1,4-Dienes2017Inngår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 139, nr 41, s. 14470-14475Artikkel i tidsskrift (Fagfellevurdert)
    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).

  • 17.
    Liu, Jianguo
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Krajangsri, Suppachai
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Yang, Jianping
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Li, Jia-Qi
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Iridium-catalysed asymmetric hydrogenation of allylic alcohols via dynamic kinetic resolution2018Inngår i: Nature Catalysis, E-ISSN 2520-1158, Vol. 1, nr 6, s. 438-443Artikkel i tidsskrift (Fagfellevurdert)
    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%).

  • 18.
    Margarita, Cristiana
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Evolution and Prospects of the Asymmetric Hydrogenation of Unfunctionalized Olefins2017Inngår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 139, nr 4, s. 1346-1356Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 19.
    Margarita, Cristiana
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Rabten, Wangchuk
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Transition-Metal-Catalyzed Regioselective Asymmetric Mono-Hydrogenation of Dienes and Polyenes2018Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 24, nr 32, s. 8022-8028Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Organic compounds containing multiple C=C bonds are attractive substrates for catalytic asymmetric hydrogenation. The full saturation of prochiral double bonds, controlling the creation of two or more stereocenters in one step, is obviously a remarkable goal. However, another fascinating and useful option is to selectively introduce a new defined stereogenic center while leaving other double bonds untouched. Thus, the retained functionalities can be further exploited in synthesis. Examples of regio- and enantioselective mono-hydrogenations of polyolefins are highlighted in this Concept article, and are divided according to the nature of the reduced double bond and the transition-metal catalyst used. Alkenes bearing coordinating functional groups are often preferentially hydrogenated by Rh- and Ru-complexes, while the more recently developed Ir-based catalysts promote the selective saturation on alkyl-substituted olefins. Relevant applications of this effective methodology in the synthesis of natural products are included to demonstrate its value in organic synthesis.

  • 20. Mbunde, Mourice Victor Nyangabo
    et al.
    Innocent, Ester
    Mabiki, Faith
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ethnobotanical survey and toxicity evaluation of medicinal plants used for fungal remedy in the Southern Highlands of Tanzania2017Inngår i: Journal of Intercultural Ethnopharmacology, ISSN 2146-8397, Vol. 6, nr 1, s. 84-96Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 21. Olsen, Esben P. K.
    et al.
    Singh, Thishana
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. Uppsala University, Sweden.
    Harris, Pernille
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Madsen, Robert
    Experimental and Theoretical Mechanistic Investigation of the Iridium-Catalyzed Dehydrogenative Decarbonylation of Primary Alcohols2015Inngår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 137, nr 2, s. 834-842Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 22.
    Peters, Byron K.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Liu, Jianguo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Margarita, Cristiana
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Formal Total Synthesis of Aliskiren2015Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 21, nr 19, s. 7292-7296Artikkel i tidsskrift (Fagfellevurdert)
    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%.

  • 23.
    Peters, Byron K.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Liu, Jianguo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Margarita, Cristiana
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Rabten, Wangchuk
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Kerdphon, Sutthichat
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Orebom, Alexander
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Morsch, Thomas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Enantio- and Regioselective Ir-Catalyzed Hydrogenation of Di- and Trisubstituted Cycloalkenes2016Inngår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 138, nr 36, s. 11930-11935Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 24.
    Peters, Byron K.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Liu, Jianguo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Margarita, Cristiana
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Rabten, Wangchuk
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Kerdphon, Sutthichat
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Paptchikhine, Alexander
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Andersson, Pher
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Enantio- and Regioselective Hydrogenation of Minimally and Densely Decorated Unsaturated CarbocyclesManuskript (preprint) (Annet vitenskapelig)
    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.

  • 25.
    Peters, Byron K.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Zhou, Taigang
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Rujirawanich, Janjira
    Cadu, Alban
    Singh, Thishana
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. Uppsala University, Sweden.
    Rabten, Wangchuk
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Kerdphon, Sutthichat
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    An Enantioselective Approach to the Preparation of Chiral Sulfones by Ir-Catalyzed Asymmetric Hydrogenation2014Inngår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 136, nr 47, s. 16557-16562Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 26.
    Ponra, Sudipta
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Rabten, Wangchuk
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Yang, Jianping
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Wu, Haibo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Kerdphon, Sutthichat
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Diastereo- and Enantioselective Synthesis of Fluorine Motifs with Two Contiguous Stereogenic Centers2018Inngår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 140, nr 42, s. 13878-13883Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The synthesis of chiral fluorine containing motifs, in particular, chiral fluorine molecules with two contiguous stereogenic centers, has attracted much interest in research due to the limited number of methods available for their preparation. Herein, we report an atom-economical and highly stereoselective synthesis of chiral fluorine molecules with two contiguous stereogenic centers via azabicyclo iridium-oxazoline-phosphine-catalyzed hydrogenation of readily available vinyl fluorides. Various aromatic, aliphatic, and heterocyclic systems with a variety of functional groups were found to be compatible with the reaction and provide the highly desirable product as single diastereomers with excellent enantioselectivities.

  • 27.
    Ponra, Sudipta
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Yang, Jianping
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Kerdphon, Sutthichat
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. University of KwaZulu-Natal, South Africa.
    Asymmetric Synthesis of Alkyl Fluorides: Hydrogenation of Fluorinated Olefins2019Inngår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 58, nr 27, s. 9282-9287Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The development of new general methods for the synthesis of chiral fluorine-containing molecules is important for several scientific disciplines. We herein disclose a straightforward method for the preparation of chiral organofluorine molecules that is based on the iridium-catalyzed asymmetric hydrogenation of trisubstituted alkenyl fluorides. This catalytic asymmetric process enables the synthesis of chiral fluorine molecules with or without carbonyl substitution. Owing to the tunable steric and electronic properties of the azabicyclo thiazole-phosphine iridium catalyst, this stereoselective reaction could be optimized and was found to be compatible with various aromatic, aliphatic, and heterocyclic systems with a variety of functional groups, providing the highly desirable products in excellent yields and enantioselectivities.

  • 28.
    Quan, Xu
    et al.
    Uppsala University, Sweden.
    Parihar, Vijay Singh
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bera, Milan
    University of KwaZulu-Natal, South Africa.
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. University of KwaZulu-Natal, South Africa.
    Iridium Catalysts with Chiral Bicyclic Pyridine-Phosphane Ligands for the Asymmetric Hydrogenation of Olefins2014Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, Vol. 2014, nr 1, s. 140-146Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 29.
    Rabten, Wangchuk
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Kärkäs, Markus D.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Åkermark, Torbjörn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Chen, Hong
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Liao, Rong-Zhen
    Tinnis, Fredrik
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sun, Junliang
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Siegbahn, Per E. M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Åkermark, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Catalytic Water Oxidation by a Molecular Ruthenium Complex: Unexpected Generation of a Single-Site Water Oxidation Catalyst2015Inngår i: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 54, nr 10, s. 4611-4620Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 30.
    Rabten, Wangchuk
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Margarita, Cristiana
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Eriksson, Lars
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ir-Catalyzed Asymmetric and Regioselective Hydrogenation of Cyclic Allylsilanes and Generation of Quaternary Stereocenters via the Hosomi-Sakurai Allylation2018Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 24, nr 7, s. 1681-1685Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 31.
    Rabten, Wangchuk
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ponra, Sudipta
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Kerdphon, Sutthichat
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Wu, Haibo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    N,P-Iridium Catalyzed Asymmetric Hydrogenation of Vinyl FluoridesManuskript (preprint) (Annet vitenskapelig)
  • 32.
    Rabten, Wangchuk
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Åkermark, Torbjörn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Kärkäs, Markus D.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Chen, Hong
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). China University of Geosciences, China.
    Sun, Junliang
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). Peking University, China.
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Åkermark, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    A ruthenium water oxidation catalyst based on a carboxamide ligand2016Inngår i: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 45, nr 8, s. 3272-3276Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 33.
    Sayers, Judy
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för matematikämnets och naturvetenskapsämnenas didaktik.
    Andrews, Paul
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för matematikämnets och naturvetenskapsämnenas didaktik.
    Developing and trialling a simple-to-use instrument for surveying teacher education students’ mathematics-related beliefs2016Inngår i: MAVI 22 Proceedings of the MAVI 22 / [ed] Palmer, Skott, 2016, Vol. 22Konferansepaper (Fagfellevurdert)
    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.

  • 34.
    Shatskiy, Andrey
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Lomoth, Reiner
    Abdel-Magied, Ahmed F.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. Nuclear Materials Authority, Egypt.
    Rabten, Wangchuk
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Laine, Tanja M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Chen, Hong
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). KTH Royal Institute of Technology, Sweden.
    Sun, Junliang
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Kärkäs, Markus D.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Johnston, Eric V.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Åkermark, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Catalyst-solvent interactions in a dinuclear Ru-based water oxidation catalyst2016Inngår i: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 45, nr 47, s. 19024-19033Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 35. Tutkowski, Brandon
    et al.
    Kerdphon, Sutthichat
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Limé, Elaine
    Helquist, Paul
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Wiest, Olaf
    Norrby, Per-Ola
    Revisiting the Stereodetermining Step in Enantioselective Iridium-Catalyzed Imine Hydrogenation2018Inngår i: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 8, nr 1, s. 615-623Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 36.
    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 Alkenes2012Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 18, nr 21, s. 6507-6513Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 37. Verendel, J. Johan
    et al.
    Nordlund, Michael
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Selective Metal-Catalyzed Transfer of H2 and CO from Polyols to Alkenes2013Inngår i: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 6, nr 3, s. 426-429Artikkel i tidsskrift (Fagfellevurdert)
  • 38. Verendel, J. Johan
    et al.
    Pamies, Oscar
    Dieguez, Montserrat
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. Univ KwaZulu Natal, Sch Chem, Durban, South Africa.
    Asymmetric Hydrogenation of Olefins Using Chiral Crabtree-type Catalysts: Scope and Limitations2014Inngår i: Chemical Reviews, ISSN 0009-2665, E-ISSN 1520-6890, Vol. 114, nr 4, s. 2130-2169Artikkel, forskningsoversikt (Fagfellevurdert)
  • 39.
    Wu, Haibo
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Margarita, Cristiana
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Jongcharoenkamol, Jira
    Singh, Thishana
    Nolan, Mark
    Andersson, Pher
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Highly Efficient Kinetic Resolution of Allylic Alcohols via Iridium-Catalyzed Asymmetric HydrogenationManuskript (preprint) (Annet vitenskapelig)
  • 40.
    Xu, Quan
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Kerdphon, Sutthichat
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    C-C Coupling of Ketones with Methanol Catalyzed by a N-Heterocyclic Carbene-Phosphine Iridium Complex2015Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 21, s. 3576-3579Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 41.
    Xu, Quan
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Kerdphon, Sutthichat
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Rujirawanich, Janjira
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Krajangsri, Suppachai
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Andersson, Pher
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Highly Active Cationic NHC, Phosphine Iridium Catalysts for Base Free Asymmetric Hydrogenation of KetonesManuskript (preprint) (Annet vitenskapelig)
  • 42.
    Xu, Quan
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Liu, Jianguo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Rabten, Wangchuk
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Diomedi, Simone
    Singh, Thishana
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Thiazole, Imidazole and Oxazoline Based N,P-Ligands for Palladium-Catalyzed Cycloisomerization of 1,6-Enynes2016Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 20, s. 3427-3433Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 43. Yotapan, Nattawut
    et al.
    Paptchikhine, Alexander
    Bera, Milan
    Avula, Satya Kumar
    Vilaivan, Tirayut
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. University of Kwazulu Natal, South Africa.
    Simple Proline-Derived Phosphine-Thiazole Iridium Complexes for Asymmetric Hydrogenation of Trisubstituted Olefins2013Inngår i: Asian Journal of Organic Chemistry, ISSN 2193-5807, Vol. 2, nr 8, s. 674-680Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 44.
    Zheng, Jia
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Margarita, Cristiana
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Krajangsri, Suppachai
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Asymmetric Total Synthesis of (-)-Juvabione via Sequential Ir-Catalyzed Hydrogenations2018Inngår i: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 20, nr 18, s. 5676-5679Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    (-)-Juvabione, a natural sesquiterpene exhibiting juvenile insect hormone activity, was synthesized constructing the two adjacent stereogenic centers via sequential Ir-catalyzed hydrogenations. The first center is generated by hydrogenation of a styrene-type double bond (99% ee). The successive monohydrogenation of a diene intermediate constitutes the key step, granting high levels of regio- and stereocontrol (94:6 dr). This novel strategy allowed the preparation of (-)-juvabione from simple starting materials in 9 steps and 17% total yield.

  • 45.
    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 Compounds2012Inngår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 134, nr 33, s. 13592-13595Artikkel i tidsskrift (Fagfellevurdert)
    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 - 45 of 45
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