Peter Mayer

Ludwig-Maximilian-University of Munich, München, Bavaria, Germany

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Publications (320)900.94 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: X-Ray structures of enamines and iminium ions derived from 2-tritylpyrrolidine (Maruoka catalyst) and 2-triphenylsilylpyrrolidine (Bolm-Christmann-Strohmann catalyst) have been determined. Kinetic investigations showed that enamines derived from phenylacetaldehyde and pyrrolidine (R = H) or 2-(triphenylsilyl)pyrrolidine (R = SiPh3) have similar reactivities toward benzhydryl cations Ar2CH+ (reference electrophiles) while the corresponding enamine derived from 2-tritylpyrrolidine (R = CPh3) is 26 times less reactive. The rationalization of this phenomenon by negative hyperconjugative interaction of the trityl group with the lone pair of the enamine nitrogen is supported by the finding that the trityl group in the 2-position of the pyrrolidine increases the electrophilic reactivity of iminium ions derived from cinnamaldehyde by a factor of 12. Consequences of these observations for the rationalization of the reactivity of the Jørgensen-Hayashi catalyst (diphenylprolinol trimethylsilyl ether) are discussed.
    Journal of the American Chemical Society 09/2014; · 10.68 Impact Factor
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    ABSTRACT: [Ru3(CO)12] reacts with pivalic acid affording violet [{Ru2(μ-O2CtBu)2(CO)4}n] (1). 1 is readily dissolved in a variety of solvents affording yellow solutions. In these solutions the dinuclear frameworks are linked by solvent molecules resulting in a novel coordination polymer structure which was elucidated by X-ray diffraction in the case of ethoxyethanol.
    Journal of Organometallic Chemistry 09/2014; 767:160–164. · 2.00 Impact Factor
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    ABSTRACT: A short total synthesis of the published structure of racemic trichodermatide A is reported. Our synthesis involves a Knoevenagel condensation/Michael addition sequence, followed by the formation of tricyclic hexahydroxanthene-dione and a diastereoselective bis-hydroxylation. The final product, the structure of which was confirmed by X-ray crystallography, has NMR spectra that are very similar but not identical to those of the isolated natural product. Quantum chemically computed 13C shifts agree well with the present NMR measurements.
    The Journal of organic chemistry. 08/2014;
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    ABSTRACT: Graphical abstract Synthesis and structure of a novel dinuclear manganese(III) complex are reported. A remarkable selectivity to the cyclohexanol has been accomplished by the manganese catalyst in the oxidation of cyclohexane using aqueous H2O2as the oxidant without any cocatalyst.
    Inorganica Chimica Acta 08/2014; · 1.69 Impact Factor
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    ABSTRACT: 1,3,5,7-Tetrakis(tetrazol-5-yl)-adamantane (H4L) was probed as a building block for the synthesis of tetrazolato/halido coordination polymers with open-network structures. MCl2 (M = Cu, Cd, Zn, Mn) was reacted with H4L in DMF at 70 °C to yield [Cu4Cl4L(DMF)5]·DMF, ; [Cd4Cl4L(DMF)7]·DMF, ; [Zn3Cl2L(DMF)4]·2DMF, and [Mn2L(DMF)2(MeOH)4]·DMF·2MeOH·2H2O, . and (Fddd) are nearly isostructural and have zeolitic structures with a {4(3)·6(2)·8}, gis or gismondine underlying net, where the role of the tetrahedral nodes is served by the coordination bonded clusters and the adamantane moiety. (P21/n) has a porous structure composed of coordination bonded layers with a (4·8(2)) fes topology joined via trans-{Zn(tetrazolate)2(DMF)4} pillars with an overall topology of {4·6(2)}{4·6(6)·8(3)}, fsc-3,5-Cmce-2. (Pca21) is composed of stacked {Mn2L} hexagonal networks. In and the ligand fulfills a symmetric role of a tetrahedral building block, while in and it fulfills rather a role of an effective trigonal unit. Methanol-exchanged and activated displayed an unusual type IV isotherm with H2 type hysteresis for N2 sorption with an expected uptake at high P/P0, but with a smaller SBET = 505.5 m(2) g(-1) compared to the calculated 1789 m(2) g(-1), which is a possible result of the framework's flexibility. For H2 sorption 0.79 wt% (1 bar, 77 K) and 0.06 wt% (1 bar, RT) uptake and Qst = -7.2 kJ mol(-1) heat of adsorption (77 K) were recorded. Weak antiferromagnetic interactions were found in and with J1 = -9.60(1), J2 = -17.2(2), J3 = -2.28(10) cm(-1) and J = -0.76 cm(-1) respectively. The formation of zeolitic structures in and , the concept of structural 'imprinting' of rigid building blocks, and design opportunities suggested as a potential hexafunctionalized biadamantane building block.
    Dalton Transactions 07/2014; · 3.81 Impact Factor
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    ABSTRACT: Nitidasin, ein komplexes Sesterterpenoid mit einem seltenen 5-8-6-5-Kohlenstoffgerüst, wurde aus dem peruanischen Naturheilmittel “Hercampuri” isoliert und ist ein Vertreter einer kleinen Gruppe von polycyclischen Sesterterpenoiden, die eine trans-Hydrindaneinheit mit einem Isopropylsubstituenten aufweisen. Als erstes Ergebnis unseres allgemeinen Ansatzes zur Synthese solcher Naturstoffe stellen wir die Totalsynthese der Titelverbindung vor. Die Schlüsselsequenz unserer stereoselektiven und konvergenten Route besteht aus der Addition einer komplexen Alkenyllithiumverbindung an ein trans-Hydrindanon, einer chemoselektiven Epoxidierung und einer Ringschlussmetathese.
    Angewandte Chemie 06/2014;
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    ABSTRACT: Nitidasin is a pentacyclic sesterterpenoid with a rare 5-8-6-5 carbon skeleton that was isolated from the Peruvian folk medicine "Hercampuri". It belongs to a small class of sesterterpenoids that feature an isopropyl trans-hydrindane moiety fused to a variety of other ring systems. As a first installment of our general approach toward these natural products, we report the total synthesis of the title compound. Our stereoselective, convergent route involves the addition of a complex alkenyl lithium compound to a trans-hydrindanone, followed by chemoselective epoxidation, ring-closing olefin metathesis, and redox adjustment.
    Angewandte Chemie International Edition in English 06/2014; · 13.45 Impact Factor
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    ABSTRACT: An aerobic iron(II)-catalyzed cleavage of catechols was developed. This reaction allows for the preparation of 2-methoxy-2 H-pyrans that can be employed as versatile building blocks for synthesis. The utility of this biomimetic oxidative cleavage is featured in the synthesis of betanidin, a natural colorant with antioxidant properties.
    Chemistry 06/2014; · 5.93 Impact Factor
  • ChemInform 04/2014; 45(15).
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    ABSTRACT: A series of α,β-unsaturated iminium ions derived from substituted cinnamaldehydes and C2- and C5-substituted chiral imidazolidin-4-ones were isolated and characterized in solution and in the solid state. The kinetics of the reactions of the iminium ions with silyl ketene acetals were determined in dichloromethane at 20 °C. The resulting second-order rate constants were used to estimate the electrophilicity E of the iminium ions according to the linear free energy relationship log k2(20 °C)=sN(N+E). The kinetics for the reactions of two of the iminium ions with tributylphosphine were studied by laser flash spectroscopy and their second-order rate constants were found to agree within a factor of 2.2 with those calculated by using the linear free energy relationship above.
    Asian Journal of Organic Chemistry. 04/2014;
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    ABSTRACT: Chloro-substituted triethylsilyl enol ethers derived from cyclohexanone and related ketones are converted with aluminum powder in the presence of indium trichloride to functionalized allylic aluminum reagents which represent a new type of synthetic equivalent of metal enolates. These allylic organometallics undergo highly diastereoselective additions to aldehydes and methyl aryl ketones, giving aldol products with a β-quaternary center.
    Organic Letters 01/2014; · 6.14 Impact Factor
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    ABSTRACT: Two new complexes of a previously obtained chromone derivative, 5-amino-8-methyl-4H-benzopyran-4-one (ligand 1), with the Co(II) (4) and Pd(II) (5) ions were synthesized and characterized by elemental analysis, IR and mass spectroscopy. The previously characterized Cu(II) complexes (2 and 3) and the newly obtained complexes of ligand 1 with Pd(II) and Co(II) have been tested as potential anticancer compounds. The molecular structure of 5 has been determined by X-ray crystallography. Biological properties, such as cytotoxicity against several cancer cell lines, the influence of the obtained compounds on the DNA structure by CD spectroscopy and agarose gel electrophoresis, have been evaluated. Also some physico-chemical properties, such as lipophilicity and stability in the aqueous solution, were tested.
    Polyhedron 01/2014; 67:136–144. · 2.05 Impact Factor
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    ABSTRACT: A new type of cascade cyclization was observed in the phosphorylation reaction of (R,R)- or (S,S)-N,N′-bis(salicylidene)cyclohexanediimine with phosphoryltrichloride, which resulted in the formation of bis(chlorophosphorylated) decahydro-2,4-di(2-hydroxyphenyl)benzo[d][1,3,6]oxadiazepine with two new stereogenic phosphorus atoms and two new stereogenic carbon atoms in the oxadiazepine ring in the β-position to phosphorus. During the synthesis, the N atom attacks the phosphorodichloridate group with the formation of the P–N bond to give an asymmetric phosphorus atom and an iminium ion. This compound with six stereogenic centers crystallizes in the monoclinic centrosymmetric space group P21/c and the crystal structure together with solution and solid-state MAS 13C and 31P NMR studies reveals a preferential formation of stereoisomers.
    Phosphorus Sulfur and Silicon and the Related Elements 01/2014; 189(2). · 0.60 Impact Factor
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    ABSTRACT: Twistane is a classic hydrocarbon with fascinating stereochemical properties. Herein we describe a series of oligomers of twistane that converges on a chiral nanorod, which we term polytwistane. A member of this series, C2-symmetric tritwistane, has been synthesized for the first time.
    Organic & Biomolecular Chemistry 11/2013; · 3.57 Impact Factor
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    ABSTRACT: The series of pyrazole derivatives (1a-4a) were used as bidentate N,N' ligands to obtain neutral Cu(II) complexes of ML2Cl2 type (1b-4b). The molecular structures of ligand 1a and Cu(II) complex 4b were determined by X-ray crystallography and theoretical DFT calculations. In this study, three functionals B3LYP, BP86 and mPW1PW91 with different basis sets and two effective core potentials Los Alamos and Stuttgart/Dresden were performed. The DFT study disclosed the usefulness of BP86 functional with SDD-ECP for Cu(II) ion and dedicated D95 basis set for other non-transition metal atoms, with the exclusion of Cl for which 6-31++G(2df,2pd) were used. The structural analysis shows that the presence of phenyl substituent in a pyrazole ring contributed to Cu-N bond elongation, which can result in different reactivity of complexes 1b and 3b. The cytotoxicity of the obtained compounds was evaluated on three cancer cells lines: HL-60, NALM-6 and WM-115. The complexes have exhibited similar moderate antiproliferative activity. All the complexes, except for 1b, were found to be more active against three cancer cell lines than uncomplexed pyrazoles. The lipophilicity and electrochemical properties of ligands and complexes was also studied. For complexes with ligand 1a and 3a only one reduction process at the metal centre occurs (Cu(II) → Cu(I)) with oxidization of Cu(I)-Cu(II) in the backward step.
    Journal of Molecular Structure 11/2013; · 1.40 Impact Factor
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    ABSTRACT: Reactions of the coordinatively unsaturated complexes [Fe2(μ-PR2)(μ-PR′2)(CO)5] [R = R′ = tBu (1); R = tBu, R′ = Cy (2)] with nitric oxide in toluene at elevated temperatures were investigated. Thus, the new complexes [Fe2(μ-PtBu2)2(NO)4] (3) and [Fe2(μ-PtBu2)(μ-PCy2)(NO)4] (4) were obtained in good yields. The molecular structure of 3 was confirmed by X-ray diffraction study. Compound 4 was also prepared from the coordinatively saturated species [Fe2(μ-PtBu2)(μ-PCy2)(CO)6] (2a) with nitric oxide in refluxing toluene. Further closely related reactions at 60 °C with the complex 1 and [FeRu(μ-PtBu2)2(CO)5] (5), respectively, were investigated using preliminary crystal structure determination results.
    Zeitschrift für anorganische Chemie 11/2013; 639(14). · 1.16 Impact Factor
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    ABSTRACT: The undecose nucleoside antibiotics herbicidin C and aureonuclemycin are biologically highly active and represent challenging targets for total synthesis. Herein, the gradual evolution of our synthetic strategy toward these natural products is described in detail. The initial route encompasses metallate addition chemistry but suffers from poor stereochemical control. In contrast, the ultimately successful strategy benefits from a variety of reagent-controlled stereoselective transformations, including a surprisingly facile and highly diastereoselective N-glycosylation. The presented work also describes new building blocks, which might find further application in carbohydrate chemistry.
    The Journal of Organic Chemistry 09/2013; · 4.56 Impact Factor
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    ABSTRACT: Kinetics of the reactions of pyridinium, isoquinolinium, and quinolinium ylides with diarylcarbenium ions, quinone methides, and arylidene malonates (reference electrophiles) have been studied in DMSO solution by UV-Vis spectroscopy. The second-order rate constants (log k2) were found to correlate linearly with the electrophilicities E of the reference electrophiles, as required by the linear free-energy relationship log k20 °C = sN(N + E) (J. Am. Chem. Soc. 2001, 123, 9500), which allowed us to derive the nucleophile-specific parameters N and sN for these ylides. Pyridinium-substitution is found to have a similar effect on the reactivity of carbanionic reaction centers as alkoxycarbonyl substitution. Agreement between the rate constants measured for the 1,3-dipolar cycloadditions of pyridinium, isoquinolinium, and quinolinium ylides with acceptor substituted dipolarophiles (arylidenemalononitrile and substituted chalcone) and those calculated from E, N, and sN shows that the above correlation can also be employed for predicting absolute rate constants of stepwise or highly unsymmetrical concerted cycloadditions. Deviations between calculated and experimental rate constants by a factor of 10(6) were demonstrated to indicate a change of reaction mechanism.
    Journal of the American Chemical Society 09/2013; · 10.68 Impact Factor
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    ABSTRACT: The (1) H NMR chemical shifts of the C(α)H protons of arylmethyl triphenylphosphonium ions in CD2 Cl2 solution strongly depend on the counteranions X(-) . The values for the benzhydryl derivatives Ph2 CHPPh3 (+) X(-) , for example, range from δH =8.25 (X(-) =Cl(-) ) over 6.23 (X(-) =BF4 (-) ) to 5.72 ppm (X(-) =BPh4 (-) ). Similar, albeit weaker, counterion-induced shifts are observed for the ortho-protons of all aryl groups. Concentration-dependent NMR studies show that the large shifts result from the deshielding of the protons by the anions, which decreases in the order Cl(-) > Br(-) ≫ BF4 (-) > SbF6 (-) . For the less bulky derivatives PhCH2 PPh3 (+) X(-) , we also find CH⋅⋅⋅Ph interactions between C(α)H and a phenyl group of the BPh4 (-) anion, which result in upfield NMR chemical shifts of the C(α)H protons. These interactions could also be observed in crystals of (p-CF3 -C6 H4 )CH2 PPh3 (+) BPh4 (-) . However, the dominant effects causing the counterion-induced shifts in the NMR spectra are the CH⋅⋅⋅X(-) hydrogen bonds between the phosphonium ion and anions, in particular Cl(-) or Br(-) . This observation contradicts earlier interpretations which assigned these shifts predominantly to the ring current of the BPh4 (-) anions. The concentration dependence of the (1) H NMR chemical shifts allowed us to determine the dissociation constants of the phosphonium salts in CD2 Cl2 solution. The cation-anion interactions increase with the acidity of the C(α)H protons and the basicity of the anion. The existence of CH⋅⋅⋅X(-) hydrogen bonds between the cations and anions is confirmed by quantum chemical calculations of the ion pair structures, as well as by X-ray analyses of the crystals. The IR spectra of the Cl(-) and Br(-) salts in CD2 Cl2 solution show strong red-shifts of the CH stretch bands. The CH stretch bands of the tetrafluoroborate salt PhCH2 PPh3 (+) BF4 (-) in CD2 Cl2 , however, show a blue-shift compared to the corresponding BPh4 (-) salt.
    Chemistry 09/2013; · 5.93 Impact Factor
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    ABSTRACT: The nucleophilicity parameters N and sN, as defined by the linear free-energy equation log k(20 °C) = sN(N + E), of the 2-imidazolines 1a–d and the related N-heterocyclic compounds 2–5 have been determined by studying the rates of their reactions with differently substituted benzhydrylium ions in dichloromethane at 20 °C by stopped-flow or laser flash photolysis techniques. It is demonstrated that the N and sN parameters thus obtained can be used to reliably predict the rate constants for their reactions with Michael acceptors of known electrophilicity E. A comparison of the nucleophilicity parameters of the imidazoline derivatives 1 with other commonly used nucleophilic organocatalysts shows that they are 10 to 103 times less nucleophilic than PPh3, 1,8-diazabicyclo[5.4.0]undec-7-ene, or 4-(dimethylamino)pyridine. The structure–reactivity relationships of these heterocycles are discussed.
    Annalen der Chemie und Pharmacie 06/2013; 2013(16). · 3.10 Impact Factor

Publication Stats

1k Citations
900.94 Total Impact Points

Institutions

  • 2001–2013
    • Ludwig-Maximilian-University of Munich
      • • Center for Integrated Protein Science
      • • Department of Chemistry
      • • Department of Biochemistry
      München, Bavaria, Germany
    • University of Lausanne
      Lausanne, Vaud, Switzerland
  • 2011
    • Collegium Medicum of the Jagiellonian University
      • Department of Inorganic and Analytical Chemistry
      Kraków, Lesser Poland Voivodeship, Poland
  • 2010
    • University of California, Berkeley
      • Department of Chemistry
      Berkeley, MO, United States
  • 2002–2010
    • Technische Universität München
      • • Chair of Biochemistry
      • • Faculty of Chemistry
      München, Bavaria, Germany
  • 2009
    • University of Zanjan
      • Department of Chemistry
      Zanjān, Zanjan, Iran
  • 2008–2009
    • University of Lodz
      • Department of Organic Chemistry
      Łódź, Łódź Voivodeship, Poland
  • 2007
    • University of Rostock
      • Institut für Chemie
      Rostock, Mecklenburg-Vorpommern, Germany
  • 2006
    • Dalhousie University
      Halifax, Nova Scotia, Canada
  • 2005–2006
    • Friedrich-Schiller-University Jena
      • Department of Inorganic and Analytical Chemistry
      Jena, Thuringia, Germany
    • University of Greifswald
      • Institute of Biochemistry
      Greifswald, Mecklenburg-Vorpommern, Germany
  • 2000–2006
    • University Hospital München
      München, Bavaria, Germany
  • 2003
    • Dongguk University
      • Department of Chemistry
      Seoul, Seoul, South Korea