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Saim Ozkar - One of the best experts on this subject based on the ideXlab platform.
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ceria supported rhodium nanoparticles superb catalytic activity in hydrogen generation from the hydrolysis of ammonia borane
Applied Catalysis B-environmental, 2016Co-Authors: Serdar Akbayrak, Yalcin Tonbul, Saim OzkarAbstract:Abstract We investigated the effect of various oxide supports on the catalytic activity of rhodium nanoparticles in hydrogen generation from the hydrolysis of ammonia borane. Among the oxide supports (CeO2, SiO2, Al2O3, TiO2, ZrO2, HfO2) ceria provides the highest catalytic activity for the rhodium(0) nanoparticles in the hydrolysis of ammonia borane. Rhodium(0) nanoparticles supported on nanoceria (Rh0/CeO2) were prepared by the impregnation of rhodium(III) ions on the surface of ceria followed by their reduction with sodium borohydride in aqueous solution at room temperature. They were isolated from the reaction solution by centrifugation and characterized by a combination of advanced analytical techniques. The catalytic activity of Rh0/CeO2 samples with various rhodium loading in the range of 0.1–4.0% wt. Rh was also tested in hydrogen generation from the hydrolysis of ammonia borane at room temperature. The highest catalytic activity was achieved by using 0.1% wt. rhodium loaded nanoceria. The resulting Rh0/CeO2 with a metal loading of 0.1% wt. Rh show superb catalytic activity in hydrogen generation from the hydrolysis of ammonia borane with a record turnover frequency value (TOF) of 2010 min−1 at 25.0 ± 0.1 °C. The superb catalytic activity of Rh0/CeO2 is ascribed to the reducible nature of ceria. The reduction of cerium(IV) to cerium(III) leads to a build-up of negative charge on the oxide surface which favors the bonding of rhodium(0) nanoparticles on the surface and, thus, their catalytic activity. Rh0/CeO2 are also reusable catalysts preserving 67% of their initial catalytic activity even after the fifth use in hydrogen generation from the hydrolysis of ammonia borane at room temperature (TOF = 1350 min−1. The work reported here also includes the kinetic studies depending on the temperature to determine the activation energy (Ea = 43 ± 2 kJ/mol) and the effect of catalyst concentration on the rate of hydrolysis of ammonia borane.
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pvp stabilized nickel 0 nanoparticles as catalyst in hydrogen generation from the methanolysis of hydrazine borane or ammonia borane
Applied Catalysis B-environmental, 2015Co-Authors: Derya Ozhava, Nihan Zulay Kilicaslan, Saim OzkarAbstract:Abstract Herein we report the results of a detailed study on the in-situ generation of poly(N-vinyl-2-pyrrolidone) (PVP) stabilized nickel(0) nanoparticles and their catalytic activity in methanolysis of hydrazine borane and ammonia borane. PVP-stabilized nickel(0) nanoparticles with an average particle size of 3.0 ± 0.7 nm were in-situ generated from the reduction of nickel(II) 2-ethylhexanoate during the methanolysis of hydrazine borane in the presence of PVP at room temperature. Polymer stabilized nickel(0) nanoparticles could be isolated from the solution by centrifugation and characterized by UV–vis spectroscopy, XPS, TEM, and SAED. PVP-stabilized nickel(0) nanoparticles are highly active and long lived catalyst in hydrogen generation from the methanolysis of hydrazine borane and ammonia borane at ambient temperature. The results of kinetic study reveal that the methanolysis is first order with respect to catalyst concentration and zero order regarding to substrate concentration in both cases. PVP-stabilized nickel(0) nanoparticles provide 14,500 turnovers in hydrogen generation from the methanolysis of hydrazine borane and 5300 turnovers from the methanolysis of ammonia borane. They also provide an initial turnover frequency of 35.6 and 12.1 min−1 for the catalytic methanolysis of hydrazine borane and ammonia borane, respectively.
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hydroxyapatite supported ruthenium 0 nanoparticles catalyst in hydrolytic dehydrogenation of ammonia borane insight to the nanoparticles formation and hydrogen evolution kinetics
Applied Catalysis B-environmental, 2013Co-Authors: Serdar Akbayrak, Pelin Erdek, Saim OzkarAbstract:Abstract When a solution of ammonia borane is added to the suspension of ruthenium(III) ions supported on hydroxyapatite, both reduction of ruthenium(III) to ruthenium(0) nanoparticles and hydrogen release from the hydrolysis of ammonia borane occur concomitantly at room temperature. Using the hydrogen evolution from the hydrolysis of ammonia borane as reporter reaction provides valuable insights to the formation kinetics of ruthenium(0) nanoparticles. Thus, the rate constants for the slow nucleation and autocatalytic surface growth of ruthenium(0) nanoparticles could be obtained. Furthermore, the evaluation of rate constants at various temperatures provides the estimation of activation energies for both reactions; Ea = 166 ± 7 kJ/mol for the nucleation and Ea = 59 ± 2 kJ/mol for the autocatalytic surface growth of ruthenium(0) nanoparticles. The ruthenium(0) nanoparticles, in situ formed during the hydrolysis of ammonia borane and supported on hydroxyapatite, could be isolated from the reaction solution and characterized by a combination of advanced analytical techniques. The results show that (i) highly dispersed ruthenium(0) nanoparticles of 4.7 ± 0.7 nm size were formed on the surface of hydroxyapatite, (ii) they are highly active catalyst in the hydrolytic dehydrogenation of ammonia borane with a turnover frequency value of 137 min−1 at 25.0 ± 0.1 °C, and (iii) they are long lived and reusable catalyst providing 87,000 turnovers for hydrogen generation from the hydrolysis of ammonia borane and preserving 92% of their initial catalytic activity even after the fifth run of hydrolysis of ammonia borane at 25.0 ± 0.1 °C. The results of kinetic study on the hydrogen generation from the hydrolysis of ammonia borane were also reported including the activation energy of 58 ± 2 kJ/mol for the hydrolytic dehydrogenation of ammonia borane.
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hydrogen generation from the hydrolysis of hydrazine borane catalyzed by rhodium 0 nanoparticles supported on hydroxyapatite
International Journal of Hydrogen Energy, 2012Co-Authors: Derya Celik, Senem Karahan, Mehmet Zahmakiran, Saim OzkarAbstract:Abstract Herein, we report the preparation and characterization of rhodium(0) nanoparticles supported on hydroxyapatite (Ca10(OH)2(PO4)6, HAP) and their catalytic use in the hydrolysis of hydrazine-borane, which attracts recent attention as promising hydrogen storage materials. Hydroxyapatite supported rhodium(0) nanoparticles were readily prepared by the hydrazine-borane reduction of rhodium(III)-exchanged hydroxyapatite in situ during the hydrolysis of hydrazine-borane at room temperature. Characterization of the resulting material by ICP–OES, TEM, SEM, EDX, XRD, XPS spectroscopies and N2 adsorption–desorption technique, which shows the formation of rhodium(0) nanoparticles well dispersed on hydroxyapatite support. The catalytic performance of these new supported rhodium(0) nanoparticles in terms of activity, lifetime and reusability was tested in the hydrolysis of hydrazine-borane. They were found to be highly active, long-lived and reusable catalyst in this important catalytic reaction even at low temperatures and high initial [substrate]/[catalyst] conditions. This report also includes the detailed kinetic study of the hydrolysis of hydrazine-borane catalyzed by hydroxyapatite supported rhodium(0) nanoparticles depending on the catalyst concentration, substrate concentration, and temperature.
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size controllable apts stabilized ruthenium 0 nanoparticles catalyst for the dehydrogenation of dimethylamine borane at room temperature
Dalton Transactions, 2012Co-Authors: Saim Ozkar, Mehmet Zahmakiran, Karine Philippot, Bruno ChaudretAbstract:Dimethylamine-borane, (CH(3))(2)NHBH(3), has been considered as one of the attractive materials for the efficient storage of hydrogen, which is still one of the key issues in the "Hydrogen Economy". In a recent communication we have reported the synthesis and characterization of 3-aminopropyltriethoxysilane stabilized ruthenium(0) nanoparticles with the preliminary results for their catalytic performance in the dehydrogenation of dimethylamine-borane at room temperature. Herein, we report a complete work including (i) effect of initial [APTS]/[Ru] molar ratio on both the size and the catalytic activity of ruthenium(0) nanoparticles, (ii) collection of extensive kinetic data under non-MTL conditions depending on the substrate and catalyst concentrations to define the rate law of Ru(0)/APTS-catalyzed dehydrogenation of dimethylamine-borane at room temperature, (iii) determination of activation parameters (E(a), ΔH(#) and ΔS(#)) for Ru(0)/APTS-catalyzed dehydrogenation of dimethylamine-borane; (iv) demonstration of the catalytic lifetime of Ru(0)/APTS nanoparticles in the dehydrogenation of dimethylamine-borane at room temperature, (v) testing the bottlability and reusability of Ru(0)/APTS nanocatalyst in the room-temperature dehydrogenation of dimethylamine-borane, (vi) quantitative carbon disulfide (CS(2)) poisoning experiments to find a corrected TTO and TOF values on a per-active-ruthenium-atom basis, (vii) a summary of extensive literature review for the catalysts tested in the catalytic dehydrogenation of dimethylamine-borane as part of the results and discussions.
Mehmet Zahmakiran - One of the best experts on this subject based on the ideXlab platform.
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hydrogen generation from the hydrolysis of hydrazine borane catalyzed by rhodium 0 nanoparticles supported on hydroxyapatite
International Journal of Hydrogen Energy, 2012Co-Authors: Derya Celik, Senem Karahan, Mehmet Zahmakiran, Saim OzkarAbstract:Abstract Herein, we report the preparation and characterization of rhodium(0) nanoparticles supported on hydroxyapatite (Ca10(OH)2(PO4)6, HAP) and their catalytic use in the hydrolysis of hydrazine-borane, which attracts recent attention as promising hydrogen storage materials. Hydroxyapatite supported rhodium(0) nanoparticles were readily prepared by the hydrazine-borane reduction of rhodium(III)-exchanged hydroxyapatite in situ during the hydrolysis of hydrazine-borane at room temperature. Characterization of the resulting material by ICP–OES, TEM, SEM, EDX, XRD, XPS spectroscopies and N2 adsorption–desorption technique, which shows the formation of rhodium(0) nanoparticles well dispersed on hydroxyapatite support. The catalytic performance of these new supported rhodium(0) nanoparticles in terms of activity, lifetime and reusability was tested in the hydrolysis of hydrazine-borane. They were found to be highly active, long-lived and reusable catalyst in this important catalytic reaction even at low temperatures and high initial [substrate]/[catalyst] conditions. This report also includes the detailed kinetic study of the hydrolysis of hydrazine-borane catalyzed by hydroxyapatite supported rhodium(0) nanoparticles depending on the catalyst concentration, substrate concentration, and temperature.
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size controllable apts stabilized ruthenium 0 nanoparticles catalyst for the dehydrogenation of dimethylamine borane at room temperature
Dalton Transactions, 2012Co-Authors: Saim Ozkar, Mehmet Zahmakiran, Karine Philippot, Bruno ChaudretAbstract:Dimethylamine-borane, (CH(3))(2)NHBH(3), has been considered as one of the attractive materials for the efficient storage of hydrogen, which is still one of the key issues in the "Hydrogen Economy". In a recent communication we have reported the synthesis and characterization of 3-aminopropyltriethoxysilane stabilized ruthenium(0) nanoparticles with the preliminary results for their catalytic performance in the dehydrogenation of dimethylamine-borane at room temperature. Herein, we report a complete work including (i) effect of initial [APTS]/[Ru] molar ratio on both the size and the catalytic activity of ruthenium(0) nanoparticles, (ii) collection of extensive kinetic data under non-MTL conditions depending on the substrate and catalyst concentrations to define the rate law of Ru(0)/APTS-catalyzed dehydrogenation of dimethylamine-borane at room temperature, (iii) determination of activation parameters (E(a), ΔH(#) and ΔS(#)) for Ru(0)/APTS-catalyzed dehydrogenation of dimethylamine-borane; (iv) demonstration of the catalytic lifetime of Ru(0)/APTS nanoparticles in the dehydrogenation of dimethylamine-borane at room temperature, (v) testing the bottlability and reusability of Ru(0)/APTS nanocatalyst in the room-temperature dehydrogenation of dimethylamine-borane, (vi) quantitative carbon disulfide (CS(2)) poisoning experiments to find a corrected TTO and TOF values on a per-active-ruthenium-atom basis, (vii) a summary of extensive literature review for the catalysts tested in the catalytic dehydrogenation of dimethylamine-borane as part of the results and discussions.
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zeolite framework stabilized nickel 0 nanoparticles active and long lived catalyst for hydrogen generation from the hydrolysis of ammonia borane and sodium borohydride
Catalysis Today, 2011Co-Authors: Mehmet Zahmakiran, Serdar Akbayrak, Derya Celik, Tugce Ayvali, Salim Caliskan, Saim OzkarAbstract:Abstract Among the hydrogen storage materials, ammonia-borane and sodium borohydride appear to be promising candidates as they can release hydrogen on hydrolysis in aqueous solution under mild conditions. Here, we report the development of a cost-effective and highly active nickel(0) nanoparticles catalyst for the hydrolysis of ammonia-borane and sodium borohydride. Nickel(0) nanoparticles confined in zeolite framework were prepared by using our previously established procedure and characterized by ICP-OES, XRD, TEM, HR-TEM, SEM, EDX, XPS, Raman spectroscopy and N 2 adsorption–desorption technique. All the results show that nickel(0) nanoparticles are formed within the framework of zeolite-Y. Nickel(0) nanoparticles confined in zeolite framework are highly active catalyst in the hydrolytic dehydrogenations of sodium borohydride and ammonia-borane. This catalyst is isolable, bottleable, redispersible and reusable. The report also includes the detailed kinetic study of the catalytic hydrolysis of both substrates, ammonia-borane and sodium borohydride depending on the catalyst concentration, substrate concentration, and temperature.
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catalytic hydrolysis of hydrazine borane for chemical hydrogen storage highly efficient and fast hydrogen generation system at room temperature
International Journal of Hydrogen Energy, 2011Co-Authors: Senem Karahan, Mehmet Zahmakiran, Saim OzkarAbstract:Abstract There has been rapidly growing interest for materials suitable to store hydrogen in solid state for transportation of hydrogen that requires materials with high volumetric and gravimetric storage capacity. B-N compounds such as ammonia-triborane, ammonia-borane and amine-borane adducts are well suited for this purpose due to their light weight, high gravimetric hydrogen storage capacity and inclination for bearing protic (N-H) and hydridic (B-H) hydrogens. In addition to them, more recent study [26] has showed that hydrazine borane with a gravimetric hydrogen storage capacity of 15.4% wt needs to be considered as another B-N compound that can be used for the storage of hydrogen. Herein we report for the first time, metal catalyzed hydrolysis of hydrazine borane (N 2 H 4 BH 3 , HB) under air at room temperature. Among the catalyst systems tested, rhodium(III) chloride was found to provide the highest catalytic activity in this reaction. In the presence of rhodium(III) chloride, the aqueous solution of hydrazine borane undergoes fast hydrolysis to release nearly 3.0 equivalent of H 2 at room temperature with previously unprecedented H 2 generation rate TOF = 12000 h −1 . More importantly, it was found that in the catalytic hydrolysis of hydrazine borane the reaction between hydrazine borane and water proceeds almost in stoichiometric proportion indicating that the efficient hydrogen generation can be achieved even from the highly concentrated solution of hydrazine borane or in the solid state when water added to the solid hydrazine borane. This finding is crucial especially for on-board application of the existing system. The work reported here also includes ( i ) finding the solubility of hydrazine borane plus its stability against self-hydrolysis in water, ( ii ) the definition of reaction stoichiometry and the identification of reaction products for the catalytic hydrolysis of hydrazine borane, ( iii ) the collection of wealthy kinetic data to demonstrate the effect of substrate and catalyst concentrations on the hydrogen generation rate and to determine the rate law for the catalytic hydrolysis of hydrazine borane, ( iv ) the investigation of the effect of temperature on the rate of hydrogen generation and determination of activation parameters ( E a , ΔH # , and ΔS # ) for the catalytic hydrolysis of hydrazine borane.
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zeolite confined copper 0 nanoclusters as cost effective and reusable catalyst in hydrogen generation from the hydrolysis of ammonia borane
International Journal of Hydrogen Energy, 2010Co-Authors: Mehmet Zahmakiran, Feyyaz Durap, Saim OzkarAbstract:Abstract Herein we report the development of a cost-effective nanocluster catalyst for the hydrolytic dehydrogenation of ammonia-borane which is considered to be one among the new hydrogen storage materials. Zeolite confined copper(0) nanoclusters were prepared by the ion-exchange of Cu2+ ions with the extra framework Na+ ions in zeolite-Y followed by reduction of the Cu2+ ions within the cavities of zeolite with sodium borohydride in aqueous solution and characterized by HR-TEM, XRD, XPS, SEM, EDX, ICP-OES, Raman spectroscopy and N2 adsorption–desorption technique. Zeolite confined copper(0) nanoclusters are found to be active catalysts in the hydrolysis of ammonia-borane even at low temperatures (≤15 °C) and stable enough for being isolated as solid materials. They provide 1300 turnovers in hydrogen generation from the hydrolysis of ammonia–borane at room temperature. The average value of turnover frequency is 46.5 h−1 for the same reaction. More importantly, zeolite confined copper(0) nanoclusters were found to be isolable, bottleable and reusable catalysts in the hydrolytic dehydrogenation of ammonia-borane; even at fifth run the complete release of hydrogen from the hydrolysis of ammonia-borane at room temperature is achieved. The work reported here also includes the full experimental details for the collection of a wealth of kinetic data to determine the activation energy and the effect of catalyst concentration on the rate for the catalytic hydrolysis of ammonia–borane.
Tomasz Bauer - One of the best experts on this subject based on the ideXlab platform.
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stereochemical course of the 4 2 cycloaddition of 1 methoxybuta 1 3 diene to n glyoxyloyl 2r Bornane 10 2 sultam the formal synthesis of compactin and mevinolin
Tetrahedron-asymmetry, 1996Co-Authors: Janusz Jurczak, Tomasz Bauer, Christian Chapuis, Artur Jezewski, Janusz KozakAbstract:Abstract The chiral heterodienophile N -glyoxyloyl-(2 R )-Bornane-10,2-sultam 2 , readily prepared from (2 R )-Bornane-10,2-sultam 1 , was used in noncatalyzed atmospheric and high-pressure as well as in [Eu(fod) 3 ]-catalyzed [4+2] cycloadditions with 1-methoxybuta-1,3-diene 3 . All the [4+2] cycloadditions studied led to diastereoisomeric mixtures of 6-substituted derivatives of 2-methoxy-5,6-dihydro-2H-pyran 4–7 . The extent of asymmetric induction in these reactions was established by 1 H NMR analysis and the absolute configuration of the thermodynamically stable products 5 and 7 by X-ray analysis, and independently by chemical correlation. Stereochemical models for both noncatalyzed and [Eu(fod) 3 ]-promoted reactions are proposed. The [4+2] cycloadduct 5 was then effectively transformed into (4 R )-hydroxy-(6S)-hydroxymethyltetrahydropyrone-2 12 , a key synthon for the lactone moiety of compactin 10 and mevinolin 11 .
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highly stereoselective addition of 2 trimethylsilyloxyfuran to n glyoxyloyl 2r Bornane 10 2 sultam
Tetrahedron-asymmetry, 1996Co-Authors: Tomasz BauerAbstract:Abstract Eu(fod) 3 -catalyzed stereoselective nucleophilic addition of 2-trimethylsilyloxyfuran to N -glyoxyloyl-(2 R )-Bornane-10,2-sultam yields g-substituted butenolides with high diastereoselectivity.
Dennis P Curran - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of Boriranes by Double Hydroboration Reactions of N-Heterocyclic Carbene Boranes and Dimethyl Acetylenedicarboxylate
Journal of the American Chemical Society, 2017Co-Authors: Timothy R. Mcfadden, Cheng Fang, Steven J. Geib, Everett Merling, Peng Liu, Dennis P CurranAbstract:Reaction of bis-(2,6-diisopropylphenyl)-imidazol-2-ylidene borane with dimethyl acetylenedicarboxylate gives 80% yield of a stable borirane (boracyclopropane) formed by formal double hydroboration along with 5% of the (E)-alkenylborane. DFT calculations suggest a mechanism where divergence to the two products occurs after a common initial stage of hydride transfer from the NHC-borane to the acetylenedicarboxylate.
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Synthesis of Boriranes by Double Hydroboration Reactions of N‑Heterocyclic Carbene Boranes and Dimethyl Acetylenedicarboxylate
2017Co-Authors: Timothy R. Mcfadden, Cheng Fang, Steven J. Geib, Everett Merling, Peng Liu, Dennis P CurranAbstract:Reaction of bis-(2,6-diisopropylphenyl)-imidazol-2-ylidene borane with dimethyl acetylenedicarboxylate gives 80% yield of a stable borirane (boracyclopropane) formed by formal double hydroboration along with 5% of the (E)-alkenylborane. DFT calculations suggest a mechanism where divergence to the two products occurs after a common initial stage of hydride transfer from the NHC-borane to the acetylenedicarboxylate
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insertion of reactive rhodium carbenes into boron hydrogen bonds of stable n heterocyclic carbene boranes
ChemInform, 2014Co-Authors: Dennis P CurranAbstract:This method also works with substituted imidazole-borane adducts as well as 1,2,4-triazole-derived borane adducts.
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insertion of reactive rhodium carbenes into boron hydrogen bonds of stable n heterocyclic carbene boranes
Journal of the American Chemical Society, 2013Co-Authors: Dennis P CurranAbstract:Readily available rhodium(II) salts catalyze reactions between NHC-boranes (NHC-BH3) and diazocarbonyl compounds (N2CRCOR′). Stable α-NHC-boryl carbonyl compounds (NHC-BH2–CHRCOR′) are isolated in good yields. The reaction is a reliable way to make boron–carbon bonds with good tolerance for variation in both the NHC-borane and diazocarbonyl components. It presumably occurs by insertion of a transient rhodium carbene into a boron–hydrogen bond of the NHC-borane. Competitive experiments show that a typical NHC-borane is highly reactive toward rhodium carbenes.
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Borenium-Catalyzed Hydroborations of Silyl-Substituted Alkenes and Alkynes with a Readily Available N‑Heterocyclic Carbene–Borane
2013Co-Authors: Anne Boussonnière, Xiangcheng Pan, Steven J. Geib, Dennis P CurranAbstract:Borenium-catalyzed hydroboration reactions of a stable, readily available N-heterocyclic carbene–borane with allyl-, alkenyl-, and alkynylsilane substrates provides either standard 1,2-hydroboration products or rearranged 1,1-hydroboration products, depending on the structure of the substrate. A competent catalyst can be generated in situ by addition of bis(trifluoromethane)sulfonimide or diiodine. In a typical 1,2-hydroboration, reaction of 1,3-dimethylimidazol-2-ylidine–borane (diMe-Imd-BH3) with 1,2-bis(trimethylsilyl)ethene provides 1,3-dimethylimidazol-2-ylidine–(1,2-bis(trimethylsilyl)ethyl)borane (diMe-Imd-BH2CH(TMS)CH2TMS)) as a stable product. In a typical 1,1-hydroboration, the reaction of diMe-Imd-BH3 with bis(trimethylsilyl)ethyne provides 1,3-dimethylimidazol-2-ylidine–bis(2,2-bis(trimethylsilyl)ethenyl)borane (diMe-Imd-BH(CHC(TMS)2)2 again as a stable product
Janusz Jurczak - One of the best experts on this subject based on the ideXlab platform.
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highly diastereoselective addition of grignard reagents to n glyoxyloyl 2r0 Bornane 10 2 sultam comparative studies
Polish Journal of Chemistry, 2002Co-Authors: K Raszplewicz, L Sikorska, Katarzyna Kiegiel, Janusz JurczakAbstract:N-Glyoxyloyl-(2R)-Bornane-10,2-sultam (3), readily prepared from (2R)-Bornane-10,2-sultam (1), was used in the Grignard reaction with methylmagnesium bromide (4a), phenylmagnesium chloride (4b), benzylmagnesium chloride (4c), allylmagnesium chloride (4d), and vinylmagnesium bromide (4e). Reactions of 3 with Grignard reagents 4a-d led to the desired adducts 5 with predominance of the (14S)-diastereoisomer. The reaction of 3 with vinylmagnesium bromide (4e) failed to give the adduct of type 5. Stereochemical models for the reactions studied are proposed.
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stereochemical course of the 4 2 cycloaddition of 1 methoxybuta 1 3 diene to n glyoxyloyl 2r Bornane 10 2 sultam the formal synthesis of compactin and mevinolin
Tetrahedron-asymmetry, 1996Co-Authors: Janusz Jurczak, Tomasz Bauer, Christian Chapuis, Artur Jezewski, Janusz KozakAbstract:Abstract The chiral heterodienophile N -glyoxyloyl-(2 R )-Bornane-10,2-sultam 2 , readily prepared from (2 R )-Bornane-10,2-sultam 1 , was used in noncatalyzed atmospheric and high-pressure as well as in [Eu(fod) 3 ]-catalyzed [4+2] cycloadditions with 1-methoxybuta-1,3-diene 3 . All the [4+2] cycloadditions studied led to diastereoisomeric mixtures of 6-substituted derivatives of 2-methoxy-5,6-dihydro-2H-pyran 4–7 . The extent of asymmetric induction in these reactions was established by 1 H NMR analysis and the absolute configuration of the thermodynamically stable products 5 and 7 by X-ray analysis, and independently by chemical correlation. Stereochemical models for both noncatalyzed and [Eu(fod) 3 ]-promoted reactions are proposed. The [4+2] cycloadduct 5 was then effectively transformed into (4 R )-hydroxy-(6S)-hydroxymethyltetrahydropyrone-2 12 , a key synthon for the lactone moiety of compactin 10 and mevinolin 11 .