MINI-CAT
Metal- and Enzyme-Catalyzed Stereoselective Reactions
Highlights - Methods - Selected Publications
In this research area, selective (chemo, regio and stereo) catalytic oxidations by transition-metal complexes (peroxy, peroxo and oxo) in homogeneous and heterogeneous phases and by enzymes (peroxidases, oxidases, lipases, etc. ) are of primary interest. Especially asymmetric catalytic oxyfunctionalizations have presented the greatest challenge in minicking what Nature is capable of doing. Important advances and contributions are the Sharpless-Katsuki epoxidation of allylic alcohols by tartrate-assisted titanium peroxy complexes and the Jacobsen-Katsuki epoxidation of unfunctionalized olefins by salen-type manganese oxo complexes. Both of these methods have been effectively used in our work. In addition, Herrmann's methyltrioxorhenium diperoxo complex has been successfully employed in selective oxidations. Besides these homogeneous catalytic oxidations, we utilize zeolites (titanium silicates such as TS-1 and Ti-beta, etc.) to perform catalytic selective oxyfunctionalization in the confined spaces of the cavities under heterogenous conditions. What organometallic reagents cannot do, we complement with enzyme-catalyzed biotransformations or employ whole bacteria and fungi to work for us as enantioselective chemical factories!
An overview of this multi-faceted and interdisciplinary research work is exhibited in Display A. The types of catalytic selective, especially asymmetric, transformations that we are
concerned with include oxidations of p-electron systems, s bonds and lone pairs. Much effort has been invested on enantioselective epoxidations of allylic alcohols, unsaturated diols and unfunctionalized alkenes, the oxidation of arenes and heteroarenes. Of great challenge is the a hydroxylation of alkanes, alcohols, fatty acids and esters, and silanes. Hetero-atom oxyfunctionalizations entail the sulfoxidation of prochiral sulfides and the N-oxide formation of amines. The reduction of chiral hydroperoxides is of interest, as are the esterification of hydroxy- and hydroperoxy-functionalized substrates, particularly of carbonyl compounds, and the selective hydrolysis of esters and lactones. Besides all these organic substrates, the catalytic oxyfunctionalization of the ligand sphere in metallorganic compounds, i.e., of functionalities with p and s bonds and with lone pairs, is of interest. Our long-term goals are to develop efficient and convenient methods for the catalytic production of optically active substances as building blocks, in organic synthesis.
Research Activities - Methods - Selected Publications
Highlights:
The hydroperoxy alcohol 1, readily available through photooxygenation, was transformed diastereoselectively with Ti(OiPr)4 into the corresponding expoxy diol, the so-called direct hydroxy-epoxidation (masked Sharpless reaction), in which the configuration of four consecutive stereogenic centers is defined.
The metal template of the above diastereoselective hydroxy-epoxidation is shown in structure 2, in which the tridentate allylic hydroperoxy alcohol (oxygen-atom donor) and the corresponding bidentate allylic diol (oxygen-atom acceptor) are tightly ligated to the central titanium metal to provide excellent stereochemical control.
From the above metal template we have learned that simple b-hydroperoxy alcohols 3 serve as excellent oxygen sources, which enables for the first time the direct epoxidation of allylic diols, a process which the classical Sharpless epoxidation with tert-butyl hydroperoxide cannot perform without recourse to protection-group chemistry.
Optically active hydroperoxides, now readily available by enantioselective horseradish-peroxidase-catalysed reduction of racemic mixtures, have been employed for the efficient (ee values up to 80%) asymmetric synthesis of sulfoxides; the transition structure for the enantioselective oxygen-atom transfer is shown in structure 4.
Application of our stereochemical probe has permitted the elucidation of the transition structure of the oxidizing species in the titanium-silicate(TS-1)-catalyzed epoxidation of chiral allylic alcohols; contrary to the literature, the peracid-type molecular arrangement in structure 5 is proposed.
The novel enantioselective and preparatively valuable hydroxylation of regio-labeled silyl enol ethers by the Jacobsen-Katsuki salen-type manganese oxo complex has allowed to elucidate the mechanistic details of the oxygen-transfer process; the transition structure 6 is suggested, with a metalloxetane as intermediate.
When the manganese(III) salen complex is treated with an oxygen source (PhIO, NaOCl) in the absence of an olefinic substrate, manganese(IV) oxo species are formed, as disclosed by detailed EPR spectroscopy and MS analysis. Depending on the reaction conditions, these complexes perform subsequently electrophilic chlorination (chloroperoxidase-type activity) or radical-type epoxidations.
For the enantioselective Jacobsen-Katsuki epoxidation of prochiral chromenes 7, dimethyldioxirane (as acetone solution) has been shown to serve as convenient and effective oxygen-atom donor in nonaqueous media.
With the help of our stereochemical probe (stereolabeled allylic alcohols), it has been shown that the epoxidations by salen manganese and porphine iron oxo complexes are diastereoselective and are assisted by hydrogen bonding in the transition state for oxygen-atom transfer (structure 8).
Unprecedented is our enantioselective catalytic hydroxylation of optically active silanes with the peroxo complex of methyltrioxorhenium (MTO), for which the concerted transition state 9 applies; essential for the high retention of configuration (ca. 95%) and chemoselectivity (no disiloxane) is the use of the urea-H2O2 adduct (UHP) instead of hydrogen peroxide, since the oxidation takes place in the urea channels (host-guest chemistry).
The catalytic MTO/UHP oxidation of 2-methylnaphthalene to menadione (10) was achieved, an industrially valuable process since this naphthoquinone is used as additive in animal feed.
Recently it has been shown that chromium(V) salen complexes chemoselectively oxidize allylic alcohols to the corresponding enones in high yield; particularly effective as oxygen source is PhI(OAc)2 compared to the usually employed PhIO. This novel catalytic oxidation is general for all types of secondary and primary alcohols.
An unprecedented success is our kinetic resolution of secondary hydroperoxides 11 (simple as well as functionalized ones) by horseradish-peroxidase-catalyzed reduction, which makes available the enantiomerically pure hydroperoxides as well as secondary alcohols on the preparative scale; most recently these biotransformations have been achieved with bacteria and fungi.
For the first time the optically active hydroperoxides 11 (R=Me, Et) have been employed in the Weitz-Scheffer epoxidation of chalcomes and shown to proceed in good enantioselectivity (up to 79% ee) when KOH is used as base catalyst. From the observed.....enantioselectivity, a metal-template effect is proposed to operate, as shown in the transition structure 12. When amines are employed as base catalyst or the metal ion (K+) is complexes with a crown ether, the opposite sense in the enantioselectivity is observed since instead of the metal template, steric effects dictate the p-facial discrimination.
The kinetic resolution of a-hydroxy acids by the oxidation with O2 catalyzed by glycolate oxidase from spinach has been accomplished, which makes available these optically pure building blocks on the preparative scale.
Optically active hydroxy vinylsilanes have been made on the preparative scale by the enantioselective horseradish-peroxidase-catalyzed reduction or lipase-catalyzed acetylation (followed by triphenylphosphine reduction) of the hydroperoxide 13.
Optically active olefinic 1,3-diols have been prepared on the preparative scale by the enantioselective horseradish-peroxidase-catalyzed reduction or lipase-catalyzed acetylation (followed by triphenylphosphine reduction) of the g-hydroperoxy alcohol 14.
The novel lipase-catalyzed alcoholysis of a-methylene b-lactones 15 makes these valuable synthetic building blocks for the first time available in optically active form.
Research Activities
- Highlights - Methods - Selected Publications
Peroxide synthesis, photooxygenation, kinetic resolution, low-temperature silica-gel chromatography, MPLC and HPLC analyses, HPLC analysis with polarimetric detection (CHIRALYSER ®), GC analysis, multi-dimentional GC analysis (MDGC), exciton-coupled circular dichroism (ECCD) analysis, EPR spectroscopy, high-field (600 MHz) NMR spectroscopy.
Research Activities - Methods - Selected Publications
Research
Activities - Highlights - Methods
Selected Publications:
Dissertations:
99. K. Roschmann "Mn(salen)- und Fe(porph)-katalysierte enantioselective Epoxidierungen: Kinetische Racematspaltung sekundärer Allylalkohole; Untersuchungen zur Diastereoselektivität mit mechanistischen Sonden", March 2002.
90. O. Weichold "Chemo- und Diastereoselektive Oxidationen in Zeolithen: Epoxidierung, Silan- und Sulfoxidation unter Katalyse von NaY/MTO, Ti-Beta, Ti-MCM-41 und Ti-ITQ-2“, May 2000.
89. P. Groer "Synthese optisch aktiver a-Methylen-b-lactame und a- Methylen-g-lactone durch lipasekatalysierte kinetische Racematspaltung", May 2000.
87. C. Mock-Knoblauch, "Asymmetrischer Sauerstofftransfer mit Metallo-Enzymen und deren Modell-Systemen: Coprinus Peroxidase-katalysierte kinetische Racematspaltung von Hydroperoxiden und enantioselektiven Sulfoxidation; Bildung und Reaktivität von MnIV(salen)-Komplexen, February 2000.
86. Z. Lukacs, "Mikrobielle asymmetrische Synthesen: Reduktion von Hydroperoxiden und Hydroxylierung von unfunktionalisierten Kohlenwasserstoffen", February 2000.
80. M. Lazarus "a -Oxidase, Glykolatoxidase und Lipase - Biokatalysatoren zur Darstellung optisch aktiver a -Hydroxysäuren", July 1998.
77. M. Korb "Titan-katalysierte, asymmetrische Oxidationen mit optisch aktiven Hydroperoxiden", March 1998.
75. R. Fell "Katalytische enantioselektive Oxidationen von Silylenolethern und Isoflavonen mit (Salen)Mangan Komplexen", March 1998.
70. M. Renz "Diastereoselektive Epoxidierung von Allylalkoholen unter homogener und heterogener Titankatalyse", February 1997.
67. U. Hoch "Enzymkatalysierte asymmetrische Synthese: Meerrettichperoxidase - Katalysator zur Darstellung optisch aktiver Hydroperoxide und Alkohole", July 1996.
64. R. Schuhmann "Selektive Oxyfunktionalisierung in der Ligandensphäre ungesättigter Organoeisen- und Organowolframkomplexe mit Singulettsauerstoff und Dioxiran", June 1996.
Papers:
907. Adam, W.; Heckel, F.; Saha-Möller, C. R.; Schreier, P. "Biocatalytic Synthesis of Optically Active Oxyfunctionalized Building Blocks with Enzymes, Chemoenzymes and Microorganisms" J. Orgmet. Chem. 2002, 661, 17-29.
897. Lazarus, M., Adam, W., Saha-Möller, C.R., Schreier, P. "Biotransformations with Oxidases and Peroxidases for the Synthesis of Optically Active Building Blocks" . In 3rd International Conference on Oxygen and Life, Kyoto, Japan; Ishimura, Y., Ed.; Elsevier Science, Amsterdam International Congress Series: 2002, 1233, 45-49.
887. Adam, W.; Roschmann, K.; Saha-Möller, C. R.; Seebach, D. "cis-Stilbene and (1a,2b,3a)-(2-Ethenyl-3- methoxycyclopropyl)benzene as Mechanistic Probes in the MnIII(salen)-Catalyzed Epoxidation: Influence of the Oxygen Source and the Counterion on the Diastereoselectivity of the Competitive Concerted and RadicalType Oxygen Transfer", J. Am. Chem. Soc. 2002, 124, 5068-5073.
870. Adam, W.; Prikhodovski, S.; Roschmann, K. J., Saha-Möller, C. R. "Oxidation of Aryl-Substituted Allylic Alcohols by an Optically Active FeIII(Porph*) Catalyst: Enantioselectivity, Diasteroselectivity and Chemoselectivity in the Epoxide versus Enone Formation", Tetrahedron: Asymmetry 2001, 12, 2677- 2681.
864. Adam, W.; Humpf, H.-U., Roschmann, K. J.; Saha- Möller, C. R. "Enantioselective Epoxidation with Chiral MnIII(salen) Catalysts: Kinetic Resolution of Aryl- Substituted Allylic Alcohols", J. Org. Chem. 2001, 66, 5796-5800.
853. Adam, W.; Lukacs, Z.; Kahle, C.; Saha-Möller, C. R., Schreier, P. "Biocatalytic Asymmetric Hydroxylation by Free and Immobilized Bacillus Megaterium Cells", J. Mol. Cat. B 2001, 377-385.
851. Adam, W., Bheema Rao, P.; Degen, H.-G.; Saha- Möller, C. R. "Asymmetric WeitzScheffer Epoxidation of Conformationally Flexible and Fixed Enones with Sterically Demanding Hydroperoxides Mediated by Optically Active Phase-Transfer Catalysts" Tetrahedron: Asymmetry, 2001, 12, 121-125.
843. Adam, W.; Corma, A.; Garcia, H.; Weichold, O. "Titanium-Catalyzed Heterogeneous Oxidations of Silanes, Chiral Allylic Alcohols, 3-Alkylcyclohexanes, and Thianthrene 5-Oxides: A Comparison of the Reactivities and Selectivities for the Large-Pore Zeolite Ti-b, the Mesoporous Ti-MCM-41, and the Layered Alumosilicate Ti-ITQ-2", J. Catal. 2000, 196, 339-344.
838. Uppili, S.; Marti, V.; Nikolaus, A.; Jockusch, S.; Adam, W.; Engel, P. S.; Turro, N. J.; Ramamurthy, V. "Heavy-Cation-Induced Phosphorescence of Alkanones and Azoalkanes in Zeolites As Hosts: Induced S1 (np*) to T1 (np*) Intersystem Crossing and S0 to T1 (np*) Absorption", J. Am. Chem. Soc. 2000, 122, 11025- 11026.
832. Adam, W.; Mock-Knoblauch, C.; Saha-Möller, C. R.; Herderich, M. "Are MnIV Species Involved in Mn(Salen)-Catalyzed Jacobsen-Katsuki Epoxidations? A Mechanistic Elucidation of Their Formation and Reaction Modes by EPR Spectroscopy, Mass-Spectral Analysis, and Product Studies: Chlorination versus Oxygen Transfer", J. Am. Chem. Soc. 2000, 122, 9685-9691.
827. Adam, W.; Lukacs, Z.; Saha-Möller, C. R.; Weckerle, B.; Schreier, P. "Microbial Asymmetric CH Oxidations of Simple Hydrocarbons: A Novel Monooxygenase Activity of the Topsoil Microorganism Bacillus megaterium", Eur. J. Org. Chem. 2000, 2923- 2926.
825. Adam, W.; Saha-Möller, C. R.; Weichold, O. "Epoxidation of trans-Cyclooctene by Methyltrioxorhenium (MTO)/H2O2: Reaction of trans Epoxide with the Monoperoxo Complex ”, J. Org. Chem. 2000, 65, 5001-5004.
824. Adam, W. Groer, P.; Humpf, H.-U.; Saha-Möller, C. R. "Synthesis of Optically Active a-Methylene b- Lactams through Lipase-Catalyzed Kinetic Resolution", J. Org. Chem. 2000, 65, 4919-4922.
820. Adam, W.; Casades, I.; Fornés, V.; Garcia, H.; Weichold, O. "UV-vis and IR Spectral Characterization of Persistent Carbenium Ions, Generated upon Incorporation of Cinnamyl Alcohols in the Acid Zeolites HZSM-5 and HMor", J. Org. Chem. 2000, 65, 3947- 3951.
819. Adam, W.; Groer, P.; Saha-Möller, C. R. "Synthesis of Optically Active a-Methylene g-Lactones Through Lipase-Catalyzed Kinetic Resolution", Tetrahedron: Asymmetry 2000, 11, 2239-2243.
815. Adam, W.; Saha-Möller, C. R.; Weichold, O. “Synthesis of Optically Active a-Methyl b-Hydroperoxy Esters by Diastereoselective Singlet-Oxygen Ene Reaction and Horseradish-Peroxidase Catalyzed Kinetic Resolution“, Chemical Monthly 2000, 131, 697-705.
813. Adam, W.; Lukacs, Z.; Saha-Möller, C. R.; Schreier, P. "Biocatalytic Kinetic Resolution of Racemic Hydroperoxides through the Enantioselective Reduction with Free and Immobilized Microorganisms", J. Am. Chem. Soc. 2000, 122, 4887-4892.
811. Adam, W.; Saha-Möller, C. R. , Weichold, O. "NaY Zeolite as Host for the Selective Heterogeneous Oxidation of Silanes and Olefins with Hydrogen Peroxide Catalyzed by Methyltrioxorhenium (MTO)", J. Org. Chem. 2000, 65, 2897-2899.
810. Adam, W.; Mitchell, C. M.; Saha-Möller, C. R.; Weichold, O. "Structure, Reactivity, and Selectivity of Metal-Peroxo Complexes versus Dioxiranes". In Structure and Bonding, Metal-Oxo and Metal-Peroxo Species in Catalytic Oxidations; Meunier, B., Ed.; Springer-Verlag: Berlin-Heidelberg-New York-Tokyo, 2000; Vol. 97, pp 237-285.
809. Akita, M.; Miyaji, T.; Muroga, N.; Mock- Knoblauch, C.; Adam, W.; Hikichi, S.; Moro-oka, Y. "Synthesis and Dehydrative Condensation of Square- Planar Mono- and Dinuclear Hydroxopalladium Complexes with the Hydrotris(3,5- diisopropylpyrazolyl)borato Ligand (TpiPr2), Tp iPr2 (Py)Pd-OH, and (m-OH)2{PdTpiPr2 (H2O)}2", Inorg. Chem. 2000, 39, 2096-2102.
807. Adam, W.; Mitchell, C. M.; Saha-Möller, C. R.; Selvam, T.; "Titanium-Catalysed Oxidation of Thianthrene 5-Oxide in Heterogeneous (Zeolites) versus Homogeneous Media: Electrophilic versus Template- Mediated Oxygen Transfer", J. Mol. Cat. A: Chemical 2000, 154, 251-255.
788. Adam, W.; Roschmann, K. J.; Saha-Möller, C. R. "Catalytic Asymmetric Aziridination of Enol Derivatives in the Presence of Chiral Copper Complexes to give Optically Active a-Amino Ketones", Eur. J. Org. Chem. 2000, 557-561.
787. Adam, W.; Lukacs, Z.; Harmsen, D.; Saha- Möller, C. R.; Schreier, P. "Biocatalytic Asymmetric Hydroxylation of Hydrocarbons with the Topsoil- Microorganism Bacillus megaterium", J. Org. Chem. 2000, 65, 878-882.
786. Adam, W.; Lukacs, Z.; Viebach, K.; Humpf, H.-U.; Saha-Möller, C. R.; Schreier, P. "Microscale Determination of the Absolute Configuration of a-Aryl- substituted Alcohols by the CD Exciton Chirality Method", J. Org. Chem. 2000, 65, 186-190.
781. Adam, W.; Lazarus, M.; Saha-Möller, C. R.; Schreier, P. "Biocatalytic Synthesis of Optically Active a-Oxyfunctionalized Carbonyl Compounds", Acc. Chem. Res. 1999, 32, 837-845.
774. Adam, W.; Mock-Knoblauch, C.; Saha-Möller, C. R. "Asymmetric Synthesis with the Enzyme Coprinus Peroxidase: Kinetic Resolution of Chiral Hydroperoxides and Enantioselective Sulfoxidation ", J. Org. Chem. 1999, 64, 4834-4839.
769. Adam, W.; Mitchell, C. M.; Saha-Möller, C. R. "Regio- and Diastereoselective Catalytic Epoxidation of Acyclic Allylic Alcohols with Methyltrioxorhenium: A Mechanistic Comparison with Metal (Peroxy and Peroxo Complexes) and Nonmetal (Peracids and Dioxirane) Oxidants", J. Org. Chem. 1999, 64, 3699-3707.
764. Adam, W.; Lukacs, Z.; Saha-Möller, C. R.; Schreier, P. "Biotransformation of (1-Phenyl)ethyl Hydroperoxide with Aspergillus Niger: A Model Study on Enzyme Selectivity and on the Induction of Peroxidase Activity", Biochim. Biophys. Acta 1999, 1427, 236-244.
759. Adam, W.; Mitchell, C. M.; Saha-Möller, C. R. "Steric and Electronic Effects in the Diastereoselective Catalytic Epoxidation of Cyclic Allylic Alcohols with Methyltrioxorhenium (MTO)", Eur. J. Org. Chem. 1999, 785-790.757.	
757. Adam, W.; Mitchell, C. M.; Saha-Möller, C. R.; Weichold, O. "Host-Guest Chemistry in a Urea Matrix: Catalytic and Selective Oxidation of Triorganosilanes to the Corresponding Silanols by Methyltrioxorhenium and the Urea/Hydrogen Peroxide Adduct", J. Am.Chem. Soc. 1999, 121, 2097-2103.
755. Adam, W.; Stegmann, V. R.; Saha-Möller, C. R. "Regio- and Diastereoselective Epoxidation of Chiral Allylic Alcohols Catalyzed by Manganese(salen) and Iron(porphine) Complexes", J. Am. Chem. Soc. 1999, 121, 1879-1882.
754. Adam, W.; Saha-Möller, C. R.; Schmid, K. S. "Lipase-Catalyzed Kinetic Resolution of Z-Configured Homoallylic Alcohols", Tetrahedron: Asymmetry 1999, 10, 315-322.
749. Häring, D.; Schüler, E.; Adam, W.; Saha-Möller, C. R.; Schreier, P. "Semisynthetic Enzymes in Asymmetric Synthesis: Enantioselective Reduction of Racemic Hydroperoxides Catalyzed by Seleno-Subtilisin", J. Org. Chem. 1999, 64, 832-835.
744. Adam, W.; Garcia, H.; Mitchell, C. M.; Saha-Möller, C. R.; Weichold, O. "The Selective Catalytic Oxidation of Silanes to Silanols with H2O2 Activated by the Ti-beta Zeolite", Chem. Commun. 1998, 2609-2610.
740. Malisch, W.; Jehle, H.; Mitchell, C.; Adam, W. "A Catalytic Pathway for the Conversion of Tungsten-silanes into Tungsten-silanols", J. Organomet. Chem. 1998, 566, 259-262.
739. Malisch,W.; Jehle, H.; Möller, S.; Saha-Möller, C. R.; Adam, W. "Regiospecific Hydroxylation of Metallodisilanes of the Iron Group - An Impressive Example of the Transition Metal Effect", Eur. J. Inorg. Chem. 1998, 1585-1587.
737. Adam, W.; Boss, B.; Harmsen, D.; Lukacs, Z.; Saha-Möller, C. R.; Schreier, P. "The Kinetic Resolution of Chiral Hydroperoxides: Hydrogen-Peroxide-Mediated Screening of Peroxidase-Active Soil Bacteria", J. Org. Chem. 1998, 63, 7598-7599.
736. Adam, W.; Boland, W.; Hartmann-Schreier, J., Humpf, H.-U.; Lazarus, M.; Saha-Möller, C. R.; Saffert, A.; Schreier, P. "a Hydroxylation of Carboxylic Acids with Molecular Oxygen Catalyzed by the a Oxidase of Peas (Pisum sativum): A Novel Biocatalytic Synthesis of Enantiomerically Pure (R)-2-Hydroxy Acids", J. Am. Chem. Soc. 1998, 120, 11044-11048.
731. Lévai, A.; Adam, W.; Fell, R. T.; Gessner, R.; Patonay, T.; Simon, A.; Tóth, G. "Enantioselective Synthesis and Chiroptical Properties of Optically Active Isoflavone Epoxides", Tetrahedron 1998, 54, 13105-13114.
729. Adam, W.; Lazarus, M.; Hoch, U.; Korb, M. N.; Saha-Möller, C. R.; Schreier, P. "Horseradish-Peroxidase-Catalyzed Enantioselective Reduction of Racemic Hydroperoxy Homoallylic Alcohols: A Novel Enzymatic Method for the Preparation of Optically Active, Unsaturated Diols and Hydroperoxy Alcohols", J. Org. Chem. 1998, 63, 6123-6127.
726. Adam, W.; Lazarus, M.; Schmerder, A.; Humpf, H.-U.; Saha-Möller, C. R.; Schreier, P. "Synthesis of Optically Active a-Hydroxy Acids by Kinetic Resolution Through Lipase-Catalyzed Enantioselective Acetylation", Eur. J. Org. Chem. 1998, 2013-2018.
725. Adam, W.; Lazarus, M.; Saha-Möller, C. R.; Weichold, O.; Hoch, U.; Häring, D.; Schreier, P. "Biotransformations with Peroxidases". In Advances in Biochemical Engineering/Biotechnology; Faber, K., Ed.; Springer Verlag: Heidelberg, 1998; Vol. 63, pp. 73-108.
719. Adam, W.; Korb, M. N.; Roschmann, K. J.; Saha-Möller, C. R. "Titanium-Catalyzed, Asymmetric Sulfoxidation of Alkyl Aryl Sulfides with Optically Active Hydroperoxides", J. Org. Chem. 1998, 63, 3423-3428.
714. Adam, W.; Fell, R. T.; Lévai, A.; Patonay, T., Peters, K.; Simon, A.; Tóth, G. "Enantioselective Epoxidation of Isoflavones by Jacobsen's Mn(III)salen Catalysts and Dimethyldioxirane Oxygen-Atom Source", Tetrahedron: Asymmetry 1998, 9, 1121-1124.
712. Aubry, J. M.; Nardello, V.; Bouttemy, S.; Wirth, T.; Linker, T.; Adam, W. "The Luminous and the Dark Side of Singlet Oxygen: Comparison Between Photochemical and Chemical Sources of Singlet Oxygen (1O2, 1Dg) in Organic Synthesis". In Selective Reactions of Metal-Activated Molecules; Werner, H.; Schreier, P., Eds.; Vieweg Verlag: Braunschweig, 1998; pp 277-281.
711. Elias, H.; Stock, F.; Adam, W.; Mitchell, C.; Neuburger, M.; Neuburger, M. "Salen-Type Oxo Vanadium Complexes as Catalysts for Sulfoxidation and Epoxidation Reactions with Hydroperoxides". In Selective Reactions of Metal-Activated Molecules; Werner, H., Schreier, P., Eds.; Vieweg Verlag: Braunschweig, 1998; pp 251-255.
710. Schenk, W. A.; Dürr, M.; Steinmetz, B.; Adam, W.; Saha-Möller, C. R. "Enantioselective Oxidation of Thioethers Using Ruthenium Complexes as Chiral Auxiliaries". In Selective Reactions of Metal-Activated Molecules; Werner, H., Schreier, P., Eds.; Vieweg Verlag: Braunschweig, 1998; pp 245-249.
709. Adam, W.; Corma, A.; Renz, M. "Chemo- and Diastereoselective Epoxidations Catalyzed by Titanium-Containing Zeolites: Evidence for a Hydrogen-Bonded, Peroxy-Type Loaded Complex as Oxidizing Species". In Selective Reactions of Metal-Activated Molecules; Werner, H., Schreier, P., Eds.; Vieweg Verlag: Braunschweig, 1998; pp 47-50.
708. Adam, W.; Fell, R. T.; Korb, M. N.; Mitchell, C. M., Saha-Möller, C. R. "Selective Metal-Catalyzed Oxygen Transfer". In Selective Reactions of Metal-Activated Molecules; Werner, H., Schreier, P., Eds.; Vieweg Verlag: Braunschweig, 1998; pp 43-45.
707. Adam, W.; Diaz, M. T.; Fell, R. T.; Groer, P.; Mock-Knoblauch, C.; Saha-Möller, C. R.; Weichold, O.;Boss, B.; Hoch, U.; Humpf, H.-U.; Lazarus, M.; Lukacs, Z.; Schreier, P. "Biocatalytic Synthesis of Optically Active Oxyfunctionalized Compounds". In Selective Reactions of Metal-Activated Molecules; Werner, H., Schreier, P., Eds.; Vieweg Verlag: Braunschweig, 1998; pp 39-42.
706. Schüler, E.; Häring, D.; Boss, B.; Herderich, M.; Schreier, P.; Adam, W.; Mock-Knoblauch, C.; Renz, M.; Saha-Möller, C. R.; Weichold, O. "The Potential of Selenium-Containing Peroxidases in Asymmetric Catalysis: Glutathion Peroxidase and Seleno-Subtilisin". In Selective Reactions of Metal-Activated Molecules; Werner, H., Schreier, P., Eds.; Vieweg Verlag: Braunschweig, 1998; pp. 35-38.
704. Adam, W.; Diaz, M. T.; Saha-Möller, C. R. "Lipase-Catalyzed Kinetic Resolution of a,b-Unsaturated a’-Acetoxy Ketones", Tetrahedron: Asymmetry 1998, 9, 791-796.
703. Adam, W.; Diaz, M. T.; Saha-Möller, C. R. "Lipase-Catalyzed Kinetic Resolution of threo-Configured 1,2-Diols: A Comparative Study of Transesterification versus Hydrolysis", Tetrahedron: Asymmetry 1998, 9, 589-598.
695. Adam, W.; Lazarus, M.; Saha-Möller, C. R.; Schreier, P. "Quantitative Transformation of Racemic 2-Hydroxy Acids into (R)-2-Hydroxy Acids by Enantioselective Oxidation with Glycolate Oxidase and Subsequent Reduction of 2-Keto Acids with D-Lactate Dehydrogenase", Tetrahedron: Asymmetry 1998, 9, 351-355.
692. Adam, W.; Fell, R. T.; Stegmann, V. R.; Saha-Möller, C. R. "Synthesis of Optically Active a-Hydroxy Carbonyl Compounds by the Catalytic, Enantioselective Oxidation of Silyl Enol Ethers and Ketene Acetals with (Salen)manganese(III) Complexes", J. Am. Chem. Soc. 1998, 120, 708-714.
684. Schenk, W. A.; Steinmetz, B.; Hagel, M.; Adam, W.; Saha-Möller, C. R. "Oxyfunctionalization of Allyl Thioether Ruthenium Complexes with Dimethyldioxirane", Z. Naturforsch. 1997, 1359-1371.
683. Adam, W.; Humpf, H.-U.; Korb, M.; Schreier, P. "The Configurational Assignment of the Optically Active 5-[(1-Hydroperoxy)ethyl]3-ethoxycarbonyl-2-methylfuran and its Alcohol by Exciton-Coupled Dichroism (ECCD)", Tetrahedron: Asymmetry 1997, 8, 3555-3558.
681. Adam, W.; Lazarus, M.; Boss, B.; Saha-Möller, C. R.; Humpf, H.-U.; Schreier, P. "Enzymatic Resolution of Chiral 2-Hydroxy Carboxylic Acids by Enantioselective Oxidation with Molecular Oxygen Catalyzed by the Glycolate Oxidase from Spinach (Spinacia Oleracea)", J. Org. Chem. 1997, 62, 7841-7843.
678. Adam, W.; Blancafort, L.; Saha-Möller, C. R. "Kinetic Resolution of Racemic Halohydrins, Precursors of Optically Active Di- and Trialkyl-Substituted Epoxides, with Lipase from Pseudomonas sp.", Tetrahedron: Asymmetry 1997, 8, 3189-3192.
673. Adam, W.; Groer, P.; Mielke, K.; Saha-Möller, C. R.; Hutterer, R.; Kiefer, W.; Nagel, V.; Schneider, F.W.; Ballmaier, D.; Schleger, Y.; Epe, B. "Photochemical and Photobiological Studies with Acridine and Phenanthridine Hydroperoxides in Cell-Free DNA", Photochem. Photobiol. 1997, 66, 26-33.
670. Adam, W.; Mock-Knoblauch, C.; Saha-Möller, C. R. "Biocatalytic Kinetic Resolution of Hydroperoxy Vinylsilanes by Horseradish Peroxidase (HRP) and Lipases, a Comparative Study", Tetrahedron: Asymmetry 1997, 8, 1947-1950.
663. Adam, W.; Corma, A.; Reddy, T. I.; Renz, M. "The Diastereoselective Catalytic Epoxidation of Chiral Allylic Alcohols by the TS-1 and Ti-beta Zeolites: Evidence for a Hydrogen-Bonded, Peroxy-Type Loaded Complex as Oxidizing Species", J. Org. Chem. 1997, 62, 3631-3637.
662. Adam, W.; Peters, K.; Renz, M. "Titanium-Catalyzed Diastereoselective Epoxidations of Ene Diols and Allylic Alcohols with b-Hydroperoxy Alcohols as Novel Oxygen Donors", J. Org. Chem. 1997, 62, 3183-3189.
661. Adam, W.; Mock-Knoblauch, C.; Saha-Möller, C. R. "Kinetic Resolution of Hydroxy Vinylsilanes by Lipase-Catalyzed Enantioselective Acetylation", Tetrahedron: Asymmetry 1997, 8, 1441-1444.
660. Hoch, U.; Humpf, H.-U.; Schreier, P.; Saha-Möller, C. R.; Adam, W. "Configurational Assignment of Optically Active Hydroperoxy Homoallylic Alcohols and the Corresponding Diols by Circular Dichroism and Multidimensial Gas Chromatography", Chirality 1997, 69-74.
659. Adam, W.; Korb, M. N. "The Titanium-Catalyzed, Asymmetric Epoxidation of Allylic Alcohols with Optically Active Hydroperoxides in the Presence of Achiral Diol Ligands", Tetrahedron: Asymmetry 1997, 8, 1131-1142.
657. Adam, W.; Corma, A.; Martinez, A.; Mitchell, C. M.; Reddy, T. I.; Renz, M.; Smerz, A. K."Diastereoselective Epoxidation of Allylic Alcohols with Hydrogen Peroxide Catalyzed by Titanium-Containing Zeolites or Methyltrioxorhenium versus Stoichiometric Oxidation with Dimethyldioxirane: Clues on the Active Species of the Zeolite Lattice", J. Mol. Cat. A: Chem. 1997, 117, 357-366.
656. Hoch, U.; Adam, W.; Fell, R.; Saha-Möller, C. R.; Schreier, P. "Horseradish Peroxidase-A Biocatalyst for the One-Pot Synthesis of Enantiomerically Pure Hydroperoxides and Alcohols", J. Mol. Cat. A: Chem. 1997, 117, 321-328.
654. Adam, W.; Groer, P.; Saha-Möller, C. R. "Enzymatic Preparation of Optically Active a-Methylene b-Lactones by Lipase-Catalyzed Kinetic Resolution Through Asymmetric Transesterification", Tetrahedron: Asymmetry 1997, 8, 833-836.
638. Adam, W.; Hoch, U.; Humpf, H.-U.; Saha-Möller, C. R.; Schreier, P. "Horseradish- Peroxidase(HRP)-Catalyzed Enantioselective Reduction of Racemic Hydroperoxy Homoallylic Alcohols: A Novel Enzymatic Method for the Preparation of Optically Active, Unsaturated Diols and Hydroperoxy Alcohols", J. Chem. Soc., Chem. Commun. 1996, 2701-2702.
631. Adam, W.; Corma, A.; Martinez, A.; Renz, M. "The Mechanism of the Double-Bond Cleavage in the Titanium-Zeolite-Catalyzed Oxidation of a-Methylstyrene by Hydrogen Peroxide: The b-Hydroperoxy Alcohol as Intermediate", Chem. Ber. 1996, 129, 1453-1455.
624. Adam, W.; Jekö, J.; Lévai, A.; Majer, Z.; Nemes, C.; Patonay, T.; Párkányi, L.; Sebök, P. "Determination of the Absolute Configuration of Optically Active 2,2-Dimethyl-3,4-epoxychromans Prepared by the Catalytic Enantioselective Epoxidation with the Dimethyldioxirane/Jacobsen Mn(II)salen System", Tetrahedron: Asymmetry 1996, 7, 2437-2446.
623. Adam, W.; Fell, R. T.; Mock-Knoblauch, C.; Saha-Möller, C. R. "Synthesis of Optically Active a-Hydroxycarbonyl Compounds by (Salen)Mn(III)-Catalyzed Oxidation of Silyl Enol Ethers and Silyl Ketene Acetals", Tetrahedron Lett. 1996, 37, 6531-6534.
622. Adam, W.; Lazarus, M.; Saha-Möller, C. R., Schreier, P. "Enantioselective a Hydroxylation of Carboxylic Acids with Molecular Oxygen Catalyzed by the a Oxidation Enzyme System of Young Pea Leaves (Pisum Sativum): A Substrate Selectivity Study", Tetrahedron: Asymmetry 1996, 7, 2287-2292.
621. Adam, W.; Diáz, M. T.; Fell, R. T.; Saha-Möller, C. R. "Kinetic Resolution of Racemic a-Hydroxy Ketones by Lipase-Catalyzed Irreversible Transesterification", Tetrahedron: Asymmetry 1996, 7, 2207-2210.
604. Adam, W.; Kumar, R.; Reddy, T. I.; Renz, M. "Chemo- and Diastereoselective Epoxidation of Chiral Allylic Alcohols with the Urea/Hydrogen-Peroxide (UHP) Adduct, Catalyzed by Titanium Silicate 1", Angew. Chem. 1996, 108, 944-947, Angew. Chem., Int. Ed. Engl. 1996, 35, 880-882.
602. Adam, W.; Korb, M. N. "Diastereoselective Oxidation of Lithium and Chlorotitanocene Enolates Derived from Camphor", Tetrahedron 1996, 52, 5487-5494.
589. Adam, W.; Mitchell, C. M. "Methyltrioxorhenium(VII)-Catalyzed Epoxidation of Alkenes with the Urea/Hydrogen-Peroxide Adduct", Angew. Chem. 1996, 108, 578-581; Angew. Chem., Int. Ed. Engl. 1996, 35, 533-535.
577. Adam, W.; Hoch, U.; Lazarus, M.; Saha-Möller, C. R.; Schreier, P. "Enzyme-Catalyzed Asymmetric Synthesis: Kinetic Resolution of Racemic Hydroperoxides by Enantioselective Reduction to Alcohols with Horseradish Peroxidase", J. Am. Chem. Soc. 1995, 117, 11898-11901.
545. Adam, W.; Jekö, J.; Lévai, A.; Nemes, C.; Patonay, T.; Sebök, P. "Enantioselective Epoxidation of 2,2-Dimethyl-2H-chromenes by Dimethyldioxirane and Jacobsen’s Mn(III)salen Catalysts, Tetrahedron Lett. 1995, 36, 3669-3672.
544. Adam, W.; Fell, R. T.; Hoch, U.; Saha-Möller, C. R.; Schreier, P. "Kinetic Resolution of Chiral a-Hydroperoxy Esters by Horseradish-Peroxidase-Catalyzed Enantioselective Reduction to a-Hydroxy Esters", Tetrahedron: Asymmetry 1995, 6, 1047-1050.
541. Hoechst AG (Herrmann, W.A.; Galamba Correia, J. D.; Fischer, R. W.; Adam, W.; Lin, J.; Saha-Möller, C. R.; Shimizu, M.), "Verfahren zur katalytischen Oxidation von aromatischen Verbindungen", EP-A 95100901.8, 1995.
538. Adam, W.; Brünker, H.-G.; Golsch, D.; Klug, P.; Lin, J.; Mitchell, C. M.; Prechtl, F.; Prein, M.; Renz, M.; Richter, M.; Saha-Möller, C. R.; Schuhmann, R.; Shimizu, M.; Smerz, A. K., Hoch, U.; Schreier, P. "Selective Oxygen Transfer". In Selective Reactions of Metal-Activated Molecules; Sundermeyer, J., Werner, H., Eds.; Vieweg Verlag: Braunschweig, 1995; pp 39-44.
537. Hoch, U.; Scheller, G.; Schmitt, M.; Schreier, P.; Adam, W.; Saha-Möller, C. R. "Enzymes in Synthetic Organic Chemistry: Selective Oxidoreductions Catalyzed by the Metalloenzymes". In Selective Reactions of Metal-Activated Molecules. Sundermeyer; J., Werner, H., Eds.; Vieweg Verlag: Braunschweig, 1995; pp 33-38.
533. Höft, E.; Hamann, H.-J.; Kunath, A.; Adam, W.; Hoch, U.; Saha-Möller, C. R.; Schreier, P. "Enzyme-Catalyzed Kinetic Resolution of Racemic Secondary Hydroperoxides", Tetrahedron: Asymmetry 1995, 6, 603-608.
532. Adam, W.; Herrmann, W.; Saha-Möller, C. R.; Shimizu, M. "Oxidation of Methoxybenzenes to p-Benzoquinones Catalyzed by Methyltrioxorhenium(VII)", J. Mol. Cat. A: Chem. 1995, 097, 15-20.
LAST CHANGE: 11.11.2003