TY  - JOUR
A1  - Kleinpeter, Erich
A1  - Heydenreich, Matthias
A1  - Koch, Andreas
A1  - Krtitschka, Angela
A1  - Krüger, Tobias
A1  - Linker, Torsten
T1  - NMR spectroscopic conformational analysis of 4-methylene-cyclohexyl pivalateThe effect of sp(2) hybridization
JF  - Magnetic resonance in chemistry
N2  - The conformational equilibrium of the axial/equatorial conformers of 4-methylene-cyclohexyl pivalate is studied by dynamic NMR spectroscopy in a methylene chloride/freon mixture. At 153K, the ring interconversion gets slow on the nuclear magnetic resonance timescale, the conformational equilibrium (-G degrees) can be examined, and the barrier to ring interconversion (G(#)) can be determined. The structural influence of sp(2) hybridization on both G degrees and G(#) of the cyclohexyl moiety can be quantified.
KW  - 4-methylene-cyclohexyl pivalate
KW  - conformational analysis
KW  - dynamic NMR spectroscopy
KW  - exo-methylene conformational effect at cyclohexane
KW  - quantum chemical calculations
Y1  - 2017
U6  - https://doi.org/10.1002/mrc.4630
SN  - 0749-1581
SN  - 1097-458X
VL  - 55
SP  - 1073
EP  - 1078
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Heydenreich, Matthias
A1  - Koch, Andreas
A1  - Sarodnick, Gerhard
A1  - Kleinpeter, Erich
T1  - Quinoxalines XIV : Synthesis, H-1, C-13, N-15 NMR spectroscopic, and quantum chemical study of 1H-pyrazolo[3,4- b]quinoxalines (flavazoles)
N2  - The synthesis of a series of 1H-pyrazolo[3,4-b]quinoxalines (flavazoles) by acylation, alkylation, halogenation, and aminomethylation of the parent compound is reported and their structure is investigated by H-1, C-13 and N-15 NMR spectroscopy. The restricted rotation about the partial C, N double bond of the N-acyl derivatives 7-10 is studied by dynamic NMR spectroscopy and the barriers to rotation are determined. In order to assign unequivocally the 15 N chemical shifts of N-4 and N-9, in case of 3-substituted flavazoles, exemplary the H-1, C-13, and N-15 NMR chemical shifts of 34, 35, and 39 are also theoretically calculated by quantum chemical methods [ab initio at different levels of theory (HF/6-3G* and B3LYP/6-31G*)]. (C) 2005 Elsevier Ltd. All rights reserved
Y1  - 2005
SN  - 0040-4020
ER  - 
TY  - JOUR
A1  - Heydenreich, Matthias
A1  - Wolf, G.
A1  - Woller, Jochen
A1  - Kleinpeter, Erich
T1  - Restricted rotation of the amino group and ring inversion in highly substituted anilines. A dynamic NMR and computational study
N2  - The reaction of cyclic ylidene malononitriles with acetylene (di)carboxylic acid esters led to the production of nine bicyclic systems incorporating highly substituted (5/6) anilines. The free energy of activation (DeltaG(#)) for the restricted rotation about the aniline-NH2 bond was experimentally measured in each case and a correlation was evident between the increase in steric strain in the ground state, the electron withdrawing capabilities of the ring substituents, and a reduction in the rotational barrier. For four of the compounds, the slow ring interconversion (chairreversible arrowchair) for the annelated saturated seven-membered ring that formed part of the bicyclic system was also evident. In these four compounds, both dynamic processes were also studied theoretically using ab initio methods whilst the ring interconversion was additionally studied using molecular dynamic simulations. The interconversion between the two stable chair forms was deemed to occur via a conformation series consisting of chairreversible arrowboatreversible arrowtwist-boatreversible arrowboatreversible arrowchair. (C) 2004 Elsevier Ltd. All rights reserved
Y1  - 2004
SN  - 0040-4020
ER  - 
TY  - JOUR
A1  - Heydenreich, Matthias
A1  - Koch, Andreas
A1  - Kovacs, J.
A1  - Toth, G.
A1  - Kleinpeter, Erich
T1  - Electronic influences on (3)J(C,H) coupling constants via -S-, -S(O)- and -SO2--: their determination, calculation and comparison of detection methods
N2  - (3)J(C,H) coupling constants via a sulfur atom in two series of compounds, both including a sulfide, a sulfoxide and a sulfone, were detected experimentally and calculated by quantum mechanical methods. In the first series (1-3) the coupling between a hydrogen, bonded to an Sp(3) carbon, and an Sp(2) carbon is treated; the second series (4- 6) deals with the coupling between a hydrogen, bonded to an Sp3 carbon, and an Sp3 carbon. Different pulse sequences (broadband HMBC, SelJres, 1D HSQMBC, J-HMBC-2, selective J-resolved long-range experiment and IMPEACH-MBC) proved to be useful in determining the long-range (3)J(C,H) coupling constants. However, the dynamic behaviour of two of the compounds (4 and 6) led to weighted averages of the two coupling constants expected (concerning equatorial and axial positions of the corresponding hydrogens). DFT calculations proved to be useful to calculate not only the (3)J(C,H) coupling constants but also the different contributions of FC, PSO, DSO and SD terms; the calculation of the Fermi contact term (FC) was found to be sufficient for the correct estimation of (3)J(C,H) coupling constants. Copyright (C) 2004 John Wiley Sons, Ltd
Y1  - 2004
SN  - 0749-1581
ER  - 
TY  - JOUR
A1  - Sarodnick, Gerhard
A1  - Heydenreich, Matthias
A1  - Linker, Torsten
A1  - Kleinpeter, Erich
T1  - Quinoxalines : Part 12: Synthesis and structural study of 1-(thiazol-2-yl)-1H-pyrazolo[3,4-b]quinoxalines - the dehydrogenative cyclization with hydroxylamine hydrochloride
Y1  - 2003
ER  - 
TY  - JOUR
A1  - Machumi, Francis
A1  - Yenesew, Abiy
A1  - Midiwo, Jacob O.
A1  - Heydenreich, Matthias
A1  - Kleinpeter, Erich
A1  - Tekwani, Babu L.
A1  - Khan, Shabana I.
A1  - Walker, Larry A.
A1  - Muhammad, Ilias
T1  - Antiparasitic and anticancer carvotacetone derivatives of Sphaeranthus bullatus
JF  - Natural product communications : an international journal for communications and reviews
N2  - The CH2Cl2-MeOH (1:1) extract of the aerial parts of Sphaeranthus bullatus, an annual herb native to tropical East Africa, showed activity against chloroquine sensitive D6 (IC50 9.7 mu g/mL) and chloroquine resistant W2 (IC50 15.0 mu g/mL) strains of Plasmodium falciparum. Seventeen secondary metabolites were isolated from the extract through conventional chromatographic techniques and identified using various spectroscopic methods. The compounds were evaluated for their in vitro antiplasmodial, antileishmanial and anticancer activities revealing activity of four carvotacetone derivatives, namely 3-acetoxy-7-hydroxy-5-tigloyloxycarvotacetone (1) 3,7-dihydroxy-5-tigloyloxycarvotacetone (2), 3-acetoxy-5,7-dihydroxycarvotacetone (3) and 3,5,7-trihydroxycarvotacetone (4); with antiplasmodial IC50 values of 1.40, 0.79, 0.60 and 3.40 mu g/mL, respectively, against chloroquine sensitive D6 strains of P. falciparum; antiplasmodial activity of IC50 2.00, 0.90, 0.68 and 2.80 mu g/mL respectively, against chloroquine resistant W2 strains of P. falciparum, antileishmanial IC50, values of 0.70, 3.00, 0.70 and 17.00 mu g/mL, respectively, against the parasite L. donovanii promastigotes, and anticancer activity against human SK-MEL, KB, BT-549 and SK-OV-3 tumor cells, with IC50 values between <1.1 - 5.3 mu g/mL, for 1-3. In addition, cytotoxic effects of the active compounds were evaluated against monkey kidney fibroblasts (VERO) and pig kidney epithelial cells (LLC-PK11). The structures of carvotacetone derivatives were determined by ID and 2D NMR spectroscopy; the absolute stereochemical configuration of 3-acetoxy-7-hydroxy-5-tigloyloxycarvotacetone (I) was determined as 3R, 4R, 5S by circular dichroism, specific rotation, H-1 NMR and 2D NMR ROESY and NOESY experiments.
KW  - Sphaeranthus bullatus
KW  - Asteraceae
KW  - Antiplasmodial
KW  - Antileishmanial
KW  - Anticancer
KW  - Carvotacetones
Y1  - 2012
SN  - 1934-578X
VL  - 7
IS  - 9
SP  - 1123
EP  - 1126
PB  - NPC
CY  - Westerville
ER  - 
TY  - JOUR
A1  - Shainyan, Bagrat A.
A1  - Suslova, Elena N.
A1  - Tran Dinh Phien, 
A1  - Shlykov, Sergey A.
A1  - Heydenreich, Matthias
A1  - Kleinpeter, Erich
T1  - 1-Methylthio-1-phenyl-1-silacyclohexane: Synthesis, conformational preferences in gas and solution by GED, NMR and theoretical calculations
JF  - Tetrahedron
N2  - 1-Methylthio-1-phenyl-1-silacyclohexane 1, the first silacyclohexane with the sulfur atom at silicon, was synthesized and its molecular structure and conformational preferences studied by gas-phase electron diffraction (GED) and low temperature C-13 and Si-29 NMR spectroscopy (LT NMR). Quantum-chemical calculations were carried out both for the isolated species and solvate complexes in gas and in polar medium. The predominance of the 1-MeSaxPheq conformer in gas phase (1-Ph-eq :1-Ph-ax = 55:45, Delta G degrees = 0.13 kcal/mol) determined from GED is consistent with that measured in the freon solution by LT NMR (1-Ph-eq:1-Ph-ax = 65:35, Delta G degrees = 0.12 kcal/mol), the experimentally measured ratios being close to that estimated by quantum chemical calculations at both the DFT and MP2 levels of theory. (C) 2019 Elsevier Ltd. All rights reserved.
KW  - 1-Methylthio-1-phenyl-1-silacyclohexane
KW  - Conformational analysis
KW  - Gas phase electron diffraction
KW  - Low-temperature C-13 and Si-29 NMR
KW  - DFT and MP2 calculations
Y1  - 2019
U6  - https://doi.org/10.1016/j.tet.2019.130677
SN  - 0040-4020
VL  - 75
IS  - 46
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Kleinpeter, Erich
A1  - Heydenreich, Matthias
A1  - Kalder, L.
A1  - Koch, Andreas
A1  - Henning, Dietrich
A1  - Kempter, Gerhard
T1  - NMR spectroscopic and theoretical structural analysis of 5,5-disubstituted hydantoins in solution
Y1  - 1997
ER  - 
TY  - JOUR
A1  - Heydenreich, Matthias
A1  - Koch, Andreas
A1  - Kleinpeter, Erich
A1  - Zimmermann, Thomas
T1  - Dynamic NMR study of the flexibility of 2-amino-3-aroyl-4,6-diaryl-pyrylium salts
Y1  - 1997
UR  - http://www.springerlink.com/content/110258
U6  - https://doi.org/10.1007/s002160050205
SN  - 0937-0633
ER  - 
TY  - JOUR
A1  - Sarodnick, Gerhard
A1  - Linker, Torsten
A1  - Heydenreich, Matthias
A1  - Koch, Andreas
A1  - Starke, Ines
A1  - Fürstenberg, Sylvia
A1  - Kleinpeter, Erich
T1  - Quinoxalines XV : convenient synthesis and structural study of pyrazolo[1,5-alpha]quinoxalines
N2  - A series of aryloxymethylquinoxaline oximes, hitherto unknown and synthesized from the corresponding aldehydes, afforded in only one step pyrazolo[1,5-;]quinoxalines in the presence of acetic anhydride at high temperatures. A formal [3,5]-sigmatropic rearrangement was proposed as the mechanistic rationale for this unprecedented transformation. Saponification with potassium hydroxide furnished the free phenol derivatives which were studied by NMR spectroscopy and accompanying theoretical DFT calculations, establishing intramolecular hydrogen bonding and the spatial magnetic properties. Additionally, mass spectrometric fragmentation was investigated by B/E-linked scans and collision-induced dissociation experiments. The fragmentation pattern devoted a new gas phase rearrangement process, which proved to be unique and characteristic for pyrazolo[1,5-;]quinoxalines.
Y1  - 2009
UR  - http://pubs.acs.org/journal/joceah
U6  - https://doi.org/10.1021/Jo802398g
SN  - 0022-3263
ER  - 
TY  - JOUR
A1  - Kleinpeter, Erich
A1  - Koch, Andreas
A1  - Heydenreich, Matthias
A1  - Chatterjee, S. K.
A1  - Rudorf, Wolf-Dieter
T1  - Study of the pi-electron distribution in push-pull alkenes by 1H and 13C NMR spectroscopy, IV : the conformation and dynamic behaviour of substituted N-Phenyl-2,3-dihydro-4(1H)-pyridones
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Benassi, Rois
A1  - Bregulla, Antje
A1  - Friedrich, Alwin
A1  - Henning, Dietrich
A1  - Heydenreich, Matthias
A1  - Mickler, Wulfhard
A1  - Kleinpeter, Erich
A1  - Kempter, Gerhard
A1  - Schilde, Uwe
A1  - Taddei, F.
T1  - NMR spectroscopic and theoretical structural study of 5-exo-methylene-substituted hydantoins
Y1  - 1998
ER  - 
TY  - JOUR
A1  - Kleinpeter, Erich
A1  - Marsat, Jean-Noël
A1  - Heydenreich, Matthias
A1  - von Berlepsch, Hans
A1  - Laschewsky, André
T1  - Self-Assembly into Multicompartment Micelles and Selective Solubilization by Hydrophilic-Lipophilic- Fluorophilic Block Copolymers
Y1  - 2011
SN  - 0024-9297
ER  - 
TY  - JOUR
A1  - Kleinpeter, Erich
A1  - Heydenreich, Matthias
A1  - Koch, Andreas
A1  - Linker, Torsten
T1  - Synthesis and NMR spectroscopic conformational analysis of esters of 4-hydroxy-cyclohexanone-the more polar the molecule the more stable the axial conformer
N2  - The esters of 4-hydroxy-cyclohexanone and a series of carboxylic acids R-COOH with R of different electronic and steric influence (R=Me, Et, n-Pr, i-Pr, n-Bu, i-Bu, sec-Bu, t-Bu, CF3, CH2Cl, CHCl2, CCl3, CH2Br, CHBr2, and CBr3) were synthesized and the conformational equilibria studied by 1H and 13C NMR spectroscopy at 103 K and at 295 K, respectively. The geometry of optimized structures of the axial/equatorial chair conformers was computed at the ab initio MO and DFT levels of theory. Only one preferred conformation was obtained for the axial and the equatorial conformer as well. When comparing the conformational equilibria of the cyclohexanone esters with those of the corresponding cyclohexyl esters a certain polarity contribution of the cyclohexanone framework was revealed, which is independent of the substituent effects and increases the stability of the axial conformers by a constant amount.
Y1  - 2012
SN  - 0040-4020
ER  - 
TY  - JOUR
A1  - Heydenreich, Matthias
A1  - Koch, Andreas
A1  - Ristau, Thomas
A1  - Knoll, Susanne
A1  - Heinicke, Jochen
A1  - Sieler, Joachim
A1  - Niemitz, Matthias
A1  - Mühlstädt, Manfred
A1  - Kleinpeter, Erich
T1  - Conformational analysis of sulfur-containing heterocycles ; part I: synthesis and structural determination of diastereomerically pure 4,6-bis(phenoxymethyl)-1,2,5-trithiepanes
Y1  - 1998
ER  - 
TY  - JOUR
A1  - Kleinpeter, Erich
A1  - Heydenreich, Matthias
A1  - Woller, Jochen
A1  - Wolf, Gunter
A1  - Koch, Andreas
A1  - Kempter, Gerhard
A1  - Pihlaja, Kalevi
T1  - Configuration and stereodynamics of exo/endoisomeric push-pull alkenes of pentadiene structure
Y1  - 1998
ER  - 
TY  - JOUR
A1  - Kleinpeter, Erich
A1  - Heydenreich, Matthias
A1  - Chatterjee, S. K.
A1  - Rudorf, Wolf-Dieter
T1  - Study of the pi-electron distribution in push-pull alkenes by 1H and 13C NMR spectroscopy, III : the conformation of 3,4-Dihydro-4-oxo-2H-thiins
Y1  - 1994
ER  - 
TY  - JOUR
A1  - Kleinpeter, Erich
A1  - Heydenreich, Matthias
A1  - Chatterjee, S. K.
A1  - Rudorf, Wolf-Dieter
T1  - Study of the pi-electron distribution in push-pull alkenes by 1H and 13C NMR spectroscopy
Y1  - 1994
ER  - 
TY  - JOUR
A1  - Kihampa, Charles
A1  - Nkunya, Mayunga H. H.
A1  - Joseph, Cosam C.
A1  - Magesa, Stephen M.
A1  - Hassanali, Ahmed
A1  - Heydenreich, Matthias
A1  - Kleinpeter, Erich
T1  - Antimosquito and antimicrobial clerodanoids and a chlorobenzoid from Tessmannia species
N2  - The clerodane diterpenoids trans-kolavenolic acid, 18-oxocleroda-3,13(E)-dien-15-oic acid, ent-(18- hydroxycarbonyl)-cleroda- 3,13(E)-dien-15-oate, 2-oxo-ent-cleroda-3,13(Z)-dien-15-oic acid and trans-2-oxo-ent-cleroda- 13(Z)-en-15-oic acid, and the chlorobenzenoid O-(3-hydroxy-4-hydroxycarbonyl-5-pentylphenyl)-3-chloro-4-methoxy-6-pentyl- 2-oxybenzoic acid were isolated from Tessmannia martiniana var pauloi and T. martiniana var matiniana. Structures were established based on interpretation of spectroscopic data. Some of the compounds exhibited significant antimosquito, antifungal and antibacterial activities.
Y1  - 2010
UR  - http://www.naturalproduct.us/
SN  - 1934-578X
ER  - 
TY  - JOUR
A1  - Kleinpeter, Erich
A1  - Heydenreich, Matthias
A1  - Kalder, L.
A1  - Koch, Andreas
A1  - Henning, Dietrich
A1  - Kempter, Gerhard
A1  - Benassi, Rois
A1  - Taddei, F.
T1  - NMR spectroscopic and theoretical structural analysis of 5,5-disubstituted hydantoins in solution
Y1  - 1997
ER  - 
TY  - JOUR
A1  - Kihampa, Charles
A1  - Nkunya, Mayunga H. H.
A1  - Joseph, Cosam C.
A1  - Magesa, Stephen M.
A1  - Hassanali, Ahmed
A1  - Heydenreich, Matthias
A1  - Kleinpeter, Erich
T1  - Anti-mosquito and antimicrobial nor-halimanoids, isocoumarins and an anilinoid from Tessmannia densiflora
N2  - The nor-halimane diterpenoid tessmannic acid and its methyl, 2-methylisopropyl and 1-methylbutyl esters, the unusual isocoumarins 8-hydroxy-6-methoxy-3-pentylisocoumarin and 7-chloro-8-hydroxy-6-methoxy-3-pentylisocoumarin, and 5- pentyl-3-methoxy-N-butylaniline were isolated from the stem and root bark extracts of Tessmannia densiflora Harms (Caesalpiniaceae) that showed mosquito larvicidal activity. The structures were determined on interpretation of spectroscopic data. Tessmannic acid and its methyl ester exhibited antibacterial and antifungal activity. The compounds also caused high larvae and adult Anopheles gambiae mosquitoe mortality effects, and stronger mosquito repellency than that shown by the standard repellent DEET, hence indicating Tessmannia species to be potential sources of bioactive natural products.
Y1  - 2009
UR  - http://www.sciencedirect.com/science/journal/00319422
U6  - https://doi.org/10.1016/j.phytochem.2009.07.024
SN  - 0031-9422
ER  - 
TY  - JOUR
A1  - Kleinpeter, Erich
A1  - Heydenreich, Matthias
A1  - Koch, Andreas
A1  - Linker, Torsten
T1  - Synthesis and NMR spectroscopic conformational analysis of esters of 4-hydroxy-cyclohexanone-the more polar the molecule the more stable the axial conformer
JF  - Tetrahedron
N2  - The esters of 4-hydroxy-cyclohexanone and a series of carboxylic acids R-COOH with R of different electronic and steric influence (R=Me, Et, n-Pr, i-Pr, n-Bu, i-Bu, sec-Bu, t-Bu, CF3, CH2Cl, CHCl2, CCl3, CH2Br, CHBr2, and CBr3) were synthesized and the conformational equilibria studied by H-1 and C-13 NMR spectroscopy at 103 K and at 295 K, respectively. The geometry of optimized structures of the axial 'equatorial chair conformers was computed at the ab initio MO and DFT levels of theory. Only one preferred conformation was obtained for the axial and the equatorial conformer as well. When comparing the conformational equilibria of the cyclohexanone esters with those of the corresponding cyclohexyl esters a certain polarity contribution of the cyclohexanone framework was revealed, which is independent of the substituent effects and increases the stability of the axial conformers by a constant amount.
KW  - 4-Substituted cyclohexanones
KW  - Conformational analysis
KW  - Dynamic NMR
KW  - Simulation of H-1 NMR spectra
KW  - Quantum chemical calculations
KW  - ALTONA equation
Y1  - 2012
U6  - https://doi.org/10.1016/j.tet.2012.01.022
SN  - 0040-4020
VL  - 68
IS  - 10
SP  - 2363
EP  - 2373
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Marsat, Jean-Noel
A1  - Heydenreich, Matthias
A1  - Kleinpeter, Erich
A1  - Berlepsch, Hans V.
A1  - Boettcher, Christoph
A1  - Laschewsky, André
T1  - Self-Assembly into multicompartment micelles and selective solubilization by Hydrophilic-Lipophilic-Fluorophilic block copolymers
JF  - Macromolecules : a publication of the American Chemical Society
N2  - Amphiphilic linear ternary block copolymers (ABC) were synthesized in three consecutive steps by the reversible addition fragmentation chain transfer (RAFT) method. Using oligo(ethylene oxide) monomethyl ether acrylate, benzyl acrylate, and 1H,1H-perfluorobutyl acrylate monomers, the triblock copolymers consist of a hydrophilic (A), a lipophilic (B), and a fluorophilic (C) block. The block sequence of the triphilic copolymers was varied systematically to provide all possible variations: ABC, ACB, and BAC. All blocks have glass transition temperatures below 0 degrees C. Self-assembly into spherical micellar aggregates was observed in aqueous solution, where hydrophobic cores undergo local phase separation into various ultrastructures as shown by cryogenic transmission electron microscopy (cryo-TEM). Selective solubilization of substantial quantities of hydrocarbon and fluorocarbon low molar mass compounds by the lipophilic and fluorophilic block, respectively, is demonstrated.
Y1  - 2011
U6  - https://doi.org/10.1021/ma200032j
SN  - 0024-9297
VL  - 44
IS  - 7
SP  - 2092
EP  - 2105
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Shainyan, Bagrat A.
A1  - Moskalik, Mikhail Yu
A1  - Heydenreich, Matthias
A1  - Kleinpeter, Erich
T1  - Conformational equilibrium and dynamic behavior of bis-N-triflyl substituted 3,8-diazabicyclo[3.2.1]octane
JF  - Magnetic resonance in chemistry
N2  - Restricted rotation about the N-S partial double bonds in a bis-N-triflyl substituted 3,8-diazabicyclo[3.2.1]octane derivative 1 has been frozen at low temperature (Delta G* = 11.6 kcal mol(-1)), and the existence of all four rotamers about the two N-S bonds, 3-in, 8-in, 3-in, 8-out, 3-out, 8-in, and 3-out, 8-out, respectively, proved experimentally by NMR spectroscopy and theoretically by DFT and MP2 calculations. Copyright (C) 2014 John Wiley & Sons, Ltd.
KW  - NMR
KW  - H-1
KW  - C-13
KW  - F-19
KW  - Dynamic NMR
KW  - Conformational equilibrium
KW  - restricted N-S rotation
Y1  - 2014
U6  - https://doi.org/10.1002/mrc.4086
SN  - 0749-1581
SN  - 1097-458X
VL  - 52
IS  - 8
SP  - 448
EP  - 452
PB  - Wiley-Blackwell
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Benassi, Rois
A1  - Bregulla, Antje
A1  - Henning, Dietrich
A1  - Heydenreich, Matthias
A1  - Kempter, Gerhard
A1  - Kleinpeter, Erich
A1  - Taddei, F.
T1  - NMR-spectroscopic and theoretical structural analysis of 5-benzyl subtituted hydantoins in solutions
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Szatmari, Istvan
A1  - Belasri, Khadija
A1  - Heydenreich, Matthias
A1  - Koch, Andreas
A1  - Kleinpeter, Erich
A1  - Fulop, Ferenc
T1  - Ortho-Quinone methide driven synthesis of new O,N- or N,N-Heterocycles
JF  - ChemistryOpen : including thesis treasury
N2  - To synthesize functionalized Mannich bases that can serve two different types of ortho-quinone methide (o-QM) intermediates, 2-naphthol and 6-hydroxyquinoline were reacted with salicylic aldehyde in the presence of morpholine. The Mannich bases that can form o-QM and aza-o-QM were also synthesized by mixing 2-naphthol, 2-nitrobenzaldehyde, and morpholine followed by reduction of the nitro group. The highly functionalized aminonaphthol derivatives were then tested in [4+2] cycloaddition with different cyclic imines. The reaction proved to be both regio- and diastereoselective. In all cases, only one reaction product was obtained. Detailed structural analyses of the new polyheterocycles as well as conformational studies including DFT modelling were performed. The relative stability of o-QMs/aza-o-QM were also calculated, and the regioselectivity of the reactions could be explained only when the cycloaddition started from aminodiol 4. It was summarized that starting from diaminonaphthol 25, the regioselectivity of the reaction is driven by the higher nucleophilicity of the amino group compared with the hydroxy group. 12H-benzo[a]xanthen-12-one (11), formed via o-QM formation, was isolated as a side product. The proton NMR spectrum of 11 proved to be very unique from NMR point of view. The reason for the extreme low-field position of proton H-1 could be accounted for by theoretical calculation of structure and spatial magnetic properties of the compound in combination of ring current effects of the aromatic moieties and steric compression within the heavily hindered H(1)-C(1)-C(12b)-C(12a)-C(12)=O structural fragment.
KW  - ortho-quinone methide (o-QMs)
KW  - modified Mannich reaction
KW  - cycloaddition
KW  - NMR spectroscopy
KW  - conformational analysis
KW  - DFT calculations
Y1  - 2019
U6  - https://doi.org/10.1002/open.201900150
SN  - 2191-1363
VL  - 8
IS  - 7
SP  - 961
EP  - 971
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Nitschke, Felix
A1  - Wang, Peixiang
A1  - Schmieder, Peter
A1  - Girard, Jean-Marie
A1  - Awrey, Donald E.
A1  - Wang, Tony
A1  - Israelian, Johan
A1  - Zhao, XiaoChu
A1  - Turnbull, Julie
A1  - Heydenreich, Matthias
A1  - Kleinpeter, Erich
A1  - Steup, Martin
A1  - Minassian, Berge A.
T1  - Hyperphosphorylation of glucosyl C6 carbons and altered structure of glycogen in the neurodegenerative epilepsy lafora disease
JF  - Cell metabolism
N2  - Laforin or malin deficiency causes Lafora disease, characterized by altered glycogen metabolism and teenage-onset neurodegeneration with intractable and invariably fatal epilepsy. Plant starches possess small amounts of metabolically essential monophosphate esters. Glycogen contains similar phosphate amounts, which are thought to originate from a glycogen synthase error side reaction and therefore lack any specific function. Glycogen is also believed to lack monophosphates at glucosyl carbon C6, an essential phosphorylation site in plant starch metabolism. We now show that glycogen phosphorylation is not due to a glycogen synthase side reaction, that C6 is a major glycogen phosphorylation site, and that C6 monophosphates predominate near centers of glycogen molecules and positively correlate with glycogen chain lengths. Laforin or malin deficiency causes C6 hyperphosphorylation, which results in malformed long-chained glycogen that accumulates in many tissues, causing neurodegeneration in brain. Our work advances the understanding of Lafora disease pathogenesis and suggests that glycogen phosphorylation has important metabolic function.
Y1  - 2013
U6  - https://doi.org/10.1016/j.cmet.2013.04.006
SN  - 1550-4131
SN  - 1932-7420
VL  - 17
IS  - 5
SP  - 756
EP  - 767
PB  - Cell Press
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Holdt, Hans-Jürgen
A1  - Müller, Holger
A1  - Potter, Matthias
A1  - Kelling, Alexandra
A1  - Schilde, Uwe
A1  - Starke, Ines
A1  - Heydenreich, Matthias
A1  - Kleinpeter, Erich
T1  - The first sandwich complex with an octa(thioether) coordination sphere : Bis(maleonitrile-tetrathia-12-crown- 4)silver(I)
N2  - The new tetrathiacrown ethers maleonitrile-tetrathia-12-crown-4 (mn12S(4)) and maleonitrile-tetrathia-13-crown- 4 (mn13S(4)) have been prepared and characterised by X-ray crystallographic analysis. These crown ethers form 2:1, 3:2 and 1: 1 complexes with AgY (Y = BF4, PF6). The crystal structures of [Ag(mn12S(4))(2)]BF4 (3a), [Ag(mn13S(4))(2)]BF4 (4a) and [Ag-2(mn13S(4))(3)](PF6)(2) (6b) have been determined. Compound 3a contains the centrosymmetric sandwich complex cation [Ag(mn12S(4))(2)](+) where each mn12S(4) ligand is coordinated to the Ag centre in an endo manner through all four S atoms. The 2:1 complex [Ag(mn12S(4))(2)](+) is the first sandwich complex with a tetrathiacrown ether and the first complex with an octa(thioether) coordination sphere. The crystal structure of compound 4a also reveals a 2:1 complex. This complex, [Ag(mnl3S(4))(2)](+), exhibits a half-sandwich structure. One mn13S(4) ligand coordinates to Ag+ by all four S donor atoms and the other 13S(4) crown by only one S atom. Compound 6b contains a dinuclear Ag complex. The Ag complexes 3a,b-8a,b were also studied by electrospray ionisation mass spectrometry. Collision-induced dissociation (CID) was used to compare the relative stability of 2:1 complexes [AgL2]+ and 1:1 complexes [AgL](+) (L = mn12S(4), mn13S(4)). The C-13 NMR chemical shifts of 2:1 and 1:1 Ag complexes and their corresponding free ligands were also estimated and compared. The free energy of the barrier of ring inversion (Delta G(double dagger)) for [Ag(mn12S(4))(2)](+) was determined to be 64 kJmol(-1).
Y1  - 2006
UR  - http://www3.interscience.wiley.com/cgi-bin/jhome/27721/
U6  - https://doi.org/10.1002/ejic.200501109
SN  - 1434-1948
ER  - 
TY  - JOUR
A1  - Schuster, Ildikó
A1  - Koch, Andreas
A1  - Heydenreich, Matthias
A1  - Kleinpeter, Erich
A1  - Forró, Enikö
A1  - Lázár, László
A1  - Sillanpää, Reijo
A1  - Fulop, Ferenc
T1  - Synthesis and Conformational Analysis of Tetrahydroisoquinoline-Fused 1,3,2-Oxazaphospholidines and 1,2,3- Oxathiazolidines
N2  - The cyclizations of tetrahydroisoquinoline 1,2-amino alcohols with phenylphosphonic dichloride, bis(2- chloroethyl)phosphoramidic dichloride, thionyl chloride and sulfuryl chloride were utilized to synthesize 1,5,6,10b- tetrahydro-1,3,2-oxazaphospholo[4,3-a]isoquinolines (2, 3), 1,5,10,10a-tetrahydro-1,3,2-oxazaphospholo[3,4- b]isoquinolines (8, 9), 1,5,6,10b-tetrahydro-1,2,3-oxathiazolo[4,3-a]isoquinolines (4-6) anda 1,5,10,10a-tetrahydro- 1,2,3-oxathiazolo[3,4-b]isoquinoline (11), which are the first representatives of these ring systems. NMR spectroscopic analysis revealed the existence of conformational equilibria that are fast on the NMR timescale. Theoretical DFT calculations pointed to the participation of generally two preferred conformers in the conformational equilibria; the positions of the equilibria were indicated by the experimental NMR spectroscopic parameters, and they are in good agreement with the theoretically calculated energy differences of the participating conformers. For two compounds, which could be not isolated (10, 12), both the preferred conformers and the stereochemistry could be concluded from the DFT calculation results.
Y1  - 2008
ER  - 
TY  - JOUR
A1  - Heydenreich, Matthias
A1  - Koch, Andreas
A1  - Szatmári, István
A1  - Fulop, Ferenc
A1  - Kleinpeter, Erich
T1  - Synthesis and conformational analysis of naphth[1,2-e][1,3]oxazino[4,3-a][1,3]isoquinoline and naphth[2,1- e][1,3]oxazino[4,3-a]isoquinoline derivatives
N2  - Through the cyclization of 1-(;-hydroxynaphthyl)-1,2,3,4-tetrahydroisoquinoline and 1-(;- hydroxynaphthyl)-1,2,3,4-tetrahydroisoquinoline with formaldehyde, phosgene, p-nitrobenzaldehyde or p-chlorophenyl isothiocyanate, 8-substituted 10,11-dihydro-8H,15bH-naphth[1,2-e][1,3]oxazino[4,3-a]isoquinolines (3 and 4) and 10,11- dihydro-8H,15bH-naphth[2,1-e][1,3]oxazino[4,3-a]isoquinolines (15 and 16) were prepared. Conformational analysis of both the piperidine and the 1,3-oxazine moieties of these heterocycles by NMR spectroscopy and an accompanying theoretical study revealed that these two conformationally flexible six-membered ring moieties prefer twisted chair conformers.
Y1  - 2008
UR  - http://www.sciencedirect.com/science/article/pii/S0040402008009150
U6  - https://doi.org/10.1016/j.tet.2008.05.025
ER  - 
TY  - JOUR
A1  - Heydenreich, Matthias
A1  - Koch, Andreas
A1  - Klod, Sabrina
A1  - Szatmari, Istvan
A1  - Fulop, Ferenc
A1  - Kleinpeter, Erich
T1  - Synthesis and conformational analysis of naphth[1', 2':5,6][1,3]oxazino[3,2-c][1,3]benzoxazine and naphth[1', 2':5,6][1,3]oxazino[3,4-c][1,3]benzoxazine derivatives
JF  - Tetrahedron
N2  - A new functional group, the hydroxy group, was inserted into a Betti base by reaction with salicylaldehyde, and the naphthoxazine derivatives thus obtained were converted by ring-closure reactions with formaldehyde, acetaldehyde, propionaldehyde or phosgene to the corresponding naphth[1',2':5,6][1,3]oxazino[3,2-c][1,3]benzoxazine derivatives. Further, the conformational analysis of these polycyclic compounds by NMR spectroscopy and an accompanying molecular modelling are reported; especially, both quantitative anisotropic ring current effects of the aromatic moieties in these compounds and steric substituent effects were employed to determine the stereochemistry of the naphthoxazinobenzoxazine derivatives.
Y1  - 2006
UR  - http://www.sciencedirect.com/science/journal/00404020
U6  - https://doi.org/10.1016/j.tet.2006.09.037
SN  - 0040-4020
VL  - 62
IS  - 48
SP  - 11081
EP  - 11089
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Kleinpeter, Erich
A1  - Szatmári, István
A1  - Lázár, László
A1  - Koch, Andreas
A1  - Heydenreich, Matthias
A1  - Fulop, Ferenc
T1  - Visualization and quantification of anisotropic effects on the 1H NMR spectra of 1,3-oxazino[4,3- alpha]isoquinolines - indirect estimates of steric compression
N2  - The anisotropic effects of the phenyl, alpha- and beta-naphthyl moieties in four series of 1,3-oxazino[4,3- a]isoquinolines on the H-1 chemical shifts of the isoquinoline protons were calculated by employing the Nucleus Independent Chemical Shift (NICS) concept and Visualized as anisotropic cones by a through-space NMR shielding grid. The signs and extents of these spatial effects on the H-1 chemical shifts of the isoquinoline protons were compared with the experimental H-1 NMR spectra. The differences between the experimental delta (H-1)/ppm values and the calculated anisotropic effects of the aromatic moieties are discussed in terms of the steric compression that occurs in the Compounds studied.
Y1  - 2009
U6  - https://doi.org/10.1016/j.tet.2009.07.038
SN  - 0040-4020
ER  - 
TY  - JOUR
A1  - Szatmari, Istvan
A1  - Heydenreich, Matthias
A1  - Koch, Andreas
A1  - Fulop, Ferenc
A1  - Kleinpeter, Erich
T1  - Unexpected isomerization of new naphth[1,3]oxazino[2,3-a] isoquinolines in solution, studied by dynamic NMR and supported by theoretical DFT computations
JF  - Tetrahedron
N2  - Through the reactions of 1-aminomethyl-2-naphthol and substituted 1-aminobenzyl-2-naphthols with 3,4-dihydroisoquinoline or 6,7-dimethoxy-3,4-dihydroisoquinoline under microwave conditions, naphth[1,2-e][1,3]oxazino[2,3-a]-isoquinoline derivatives were prepared in good yields. The latter reaction was extended by using 2-aminoarylmethyl-1-naphthols, leading to isomeric naphth-[2,1-e][1,3]oxazino[2,3-a] isoquinolines. Beside the detailed NMR spectroscopic and theoretical study of both stereochemistry and dynamic behaviour of these new conformational flexible heterocyclic ring systems an unexpected dynamic process between two diastereomers was observed in solution, studied by variable temperature H-1 NMR spectroscopy and the mechanism proved by theoretical DFT computations.
KW  - 3,4-Dihydroisoquinoline
KW  - Aminonaphthol
KW  - Dynamic NMR spectroscopy
KW  - DFT calculations
KW  - Conformational analysis
Y1  - 2013
U6  - https://doi.org/10.1016/j.tet.2013.06.094
SN  - 0040-4020
VL  - 69
IS  - 35
SP  - 7455
EP  - 7465
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Kleinpeter, Erich
A1  - Csütörtöki, Renáta
A1  - Szatmári, István
A1  - Heydenreich, Matthias
A1  - Koch, Andreas
A1  - Starke, Ines
A1  - Fulop, Ferenc
T1  - Novel piperidine-fused benzoxazino- and quinazolinonaphthoxazines-synthesis and conformational study
N2  - The reactions of 1-(amino(2-hydroxyphenyl)methyl)-2-naphthol (3) and 1-(amino(2-aminophenyl)methyl)-2-naphthol (6) with glutardialdehyde resulted in the formation of piperidine-fused benzoxazinonaphthoxazine 4 and quinazolinonaphthoxazine 7, respectively, both in diastereopure form. The full conformational search protocols of 4 and 7 were successfully carried out by NMR spectroscopy and accompanying molecular modelling; the global minimum-energy conformers of all diastereomers were computed, and the assignments of the most stable stereoisomers, Gtct1 for 4 and Gtct1 for 7, were corroborated by spatial NOE information relating to the H7a-H10a-H15b and H,H coupling patterns of the protons in the flexible part of the piperidine moiety. Additionally, mass spectrometric fragmentation was investigated in collision-induced dissociation experiments. The elemental compositions of the ions were determined by accurate mass measurements.
Y1  - 2012
SN  - 0040-4020
ER  - 
TY  - JOUR
A1  - Thóth, Diána
A1  - Szatmári, István
A1  - Heydenreich, Matthias
A1  - Koch, Andreas
A1  - Kleinpeter, Erich
A1  - Fulop, Ferenc
T1  - Synthesis and conformational analysis of naphthylnaphthoxazine derivatives
N2  - Four new primary aminonaphthols (4, 5, 9 and 10) were synthesized from 1- or 2-naphthol and 1- or 2- naphthaldehyde via naphthoxazines in modified Mannich condensations. Simple ring-closure reactions of these aminonaphthols with paraformaldehyde, 4-nitrobenzaldehyde, phosgene or 4-chlorophenyl isothiocyanate led to new heterocyclic derivatives. In these transformations, either an sp2 or an sp3 carbon was inserted between the hydroxy and amino groups. The effects of substituents and the naphthyl ring on the conformation were investigated by means of NMR measurements, employing both dipolar and scalar couplings. The structures were confirmed by DFT quantum chemical calculations involving computed coupling constants, intramolecular distances between nuclei and the relative energies of the preferred conformers.
Y1  - 2009
UR  - http://www.sciencedirect.com/science/journal/00222860
U6  - https://doi.org/10.1016/j.molstruc.2009.04.015
SN  - 0166-1280
ER  - 
TY  - JOUR
A1  - Szatmari, Istvan
A1  - Toth, Diana
A1  - Koch, Andreas
A1  - Heydenreich, Matthias
A1  - Kleinpeter, Erich
A1  - Fulop, Ferenc
T1  - Study of the substituent-influenced anomeric effect in the ring-chain tautomerism of 1-alkyl-3-aryl-naphth[1,2- e][1,3]oxazines
N2  - The stabilities of the trans (B) and cis (C) tautomeric ring forms that are experimentally observed in the ring- chain tautomeric interconversion of 1-alkyl-3-aryl-2,3-dihydro-1H-naphth[1,2-e][1,3]oxazines has been investigated. Stability differences are explained by the analysis of the natural bond orbital results for the lone pairs of electrons that are on the heteroatoms in the oxazine ring system and by regression analysis of the calculated 13C NMR chemical shift values.
Y1  - 2006
UR  - http://onlinelibrary.wiley.com/doi/10.1002/ejoc.200600563/pdf
U6  - https://doi.org/10.1002/ejoc.200600563
ER  - 
TY  - JOUR
A1  - Csütörtöki, Renáta
A1  - Szatmári, István
A1  - Koch, Andreas
A1  - Heydenreich, Matthias
A1  - Kleinpeter, Erich
A1  - Fulop, Ferenc
T1  - Synthesis and conformational analysis of new naphth[1,2-e][1,3]oxazino[3,4-c]quinazoline derivatives
Y1  - 2011
SN  - 0040-4020
ER  - 
TY  - JOUR
A1  - Csütörtöki, Renata
A1  - Szatmari, Istvan
A1  - Koch, Andreas
A1  - Heydenreich, Matthias
A1  - Kleinpeter, Erich
A1  - Fulop, Ferenc
T1  - Syntheses and conformational analyses of new naphth[1,2-e][1,3]oxazino[3,2-c] quinazolin-13-ones
JF  - Tetrahedron
N2  - The syntheses of naphth[1,2-e][1,3]oxazino[3,2-c]quinazolin-13-one derivatives (3a-f) were achieved by the solvent-free heating of benzyloxycarbonyl-protected intermediates (2a-f) with MeONa. For intermediates 2a-f, prepared by the reactions of substituted aminonaphthols with benzyl N-(2-formylphenyl)carbamate, not only the expected trans ring form B and chain form A(1), but also the rearranged chain form A(2) as a new tautomer were detected in DMSO at room temperature. The quantity of A(2) in the tautomeric mixture was changed with time.
 Conformational analyses of the target heterocycles 3a-f by NMR spectroscopy and accompanying theoretical calculations at the DFT level of theory revealed that the oxazine ring preferred a twisted chair conformation and the quinazolone ring was planar. Besides the conformations, both the configurations at C-7a and C-15 and the preferred rotamers of the 1-naphthyl substituent at C-15 were assigned, which allowed evaluation of the aryl substituent-dependent steric hindrance in this part of the molecules. Configurational assignments were corroborated by quantifying the ring current effect of 15-aryl in terms of spatial NICS.
KW  - Naphthoxazinoquinazolinones
KW  - Aminonaphthols
KW  - NMR spectroscopy
KW  - Conformational analysis
KW  - Theoretical calculations
KW  - Ring current effect
Y1  - 2012
U6  - https://doi.org/10.1016/j.tet.2012.04.026
SN  - 0040-4020
VL  - 68
IS  - 24
SP  - 4600
EP  - 4608
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Csuetoertoeki, Renata
A1  - Szatmari, Istvan
A1  - Heydenreich, Matthias
A1  - Koch, Andreas
A1  - Starke, Ines
A1  - Fueloep, Ferenc
A1  - Kleinpeter, Erich
T1  - Novel piperidine-fused benzoxazino- and
 quinazolinonaphthoxazines-synthesis and conformational study
JF  - TETRAHEDRON
N2  - The reactions of 1-(amino(2-hydroxyphenyl)methyl)-2-naphthol (3) and 1-(amino(2-aminophenyl) methyl)-2-naphthol (6) with glutardialdehyde resulted in the formation of piperidine-fused benzox-azinonaphthoxazine 4 and quinazolinonaphthoxazine 7, respectively, both in diastereopure form. The full conformational search protocols of 4 and 7 were successfully carried out by NMR spectroscopy and accompanying molecular modelling; the global minimum-energy conformers of all diastereomers were computed, and the assignments of the most stable stereoisomers, G(tct)(1) for 4 and G(tct)(1) for 7, were corroborated by spatial NOE information relating to the H-7a-H-10a-H-15b and H,H coupling patterns of the protons in the flexible part of the piperidine moiety. Additionally, mass spectrometric fragmentation was investigated in collision-induced dissociation experiments. The elemental compositions of the ions were determined by accurate mass measurements. (C) 2012 Elsevier Ltd. All rights reserved.
KW  - Quinazolines
KW  - Naphthoxazines
KW  - DFT structural study
KW  - Conformational analysis
KW  - NMR spectroscopy
Y1  - 2012
U6  - https://doi.org/10.1016/j.tet.2012.05.048
SN  - 0040-4020
VL  - 68
IS  - 31
SP  - 6284
EP  - 6288
PB  - PERGAMON-ELSEVIER SCIENCE LTD
CY  - OXFORD
ER  - 
TY  - JOUR
A1  - Csuetoertoeki, Renata
A1  - Szatmari, Istvan
A1  - Koch, Andreas
A1  - Heydenreich, Matthias
A1  - Kleinpeter, Erich
A1  - Fueloep, Ferenc
T1  - Synthesis and conformational analysis of new naphth[1,2-e][1,3]oxazino[3,4-c]quinazoline derivatives
JF  - Tetrahedron
N2  - A new highly functionalized aminonaphthol derivative, 1-(amino(2-aminophenyl)methyl)-2-naphthol (4), was synthesized by the reaction of 2-naphthol, 2-nitrobenzaldehyde and tert-butyl carbamate or benzyl carbamate, followed by reduction and/or removal of the protecting group. The aminonaphthol derivative thus obtained was converted in ring-closure reactions with formaldehyde. benzaldehyde and/or phosgene to the corresponding naphth[1,2-e][1,3]oxazino[3,4-c]quinazoline derivatives. The conformational analysis of some derivatives by NMR spectroscopy and accompanying molecular modelling are also reported.
KW  - Naphthoxazinoquinazolines
KW  - NMR
KW  - Conformational analysis
KW  - DFT calculations
KW  - Hammett-Brown plots
Y1  - 2011
U6  - https://doi.org/10.1016/j.tet.2011.08.074
SN  - 0040-4020
VL  - 67
IS  - 44
SP  - 8564
EP  - 8571
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Belasri, Khadija
A1  - Topal, Leila
A1  - Heydenreich, Matthias
A1  - Koch, Andreas
A1  - Kleinpeter, Erich
A1  - Fulop, Ferenc
A1  - Szatmari, Istvan
T1  - Synthesis and conformational analysis of naphthoxazine-fused phenanthrene derivatives
JF  - Molecules
N2  - The synthesis of new phenanthr[9,10-e][1,3]oxazines was achieved by the direct coupling of 9-phenanthrol with cyclic imines in the modified aza-Friedel-Crafts reaction followed by the ring closure of the resulting bifunctional aminophenanthrols with formaldehyde. Aminophenanthrol-type Mannich bases were synthesised and transformed to phenanthr[9,10-e][1,3]oxazines via [4 + 2] cycloaddition. Detailed NMR structural analyses of the new polyheterocycles as well as conformational studies including Density Functional Theory (DFT) modelling were performed. The relative stability of ortho-quinone methides (o-QMs) was calculated, the geometries obtained were compared with the experimentally determined NMR structures, and thereby, the regioselectivity of the reactions has been assigned.
KW  - modified Mannich reaction
KW  - cyclic imines
KW  - [4+2] cycloaddition
KW  - NMR
KW  - spectroscopy
KW  - conformational analysis
KW  - DFT calculations
Y1  - 2020
U6  - https://doi.org/10.3390/molecules25112524
SN  - 1420-3049
VL  - 25
IS  - 11
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Barta, Petra
A1  - Szatmari, Istvan
A1  - Fueloep, Ferenc
A1  - Heydenreich, Matthias
A1  - Koch, Andreas
A1  - Kleinpeter, Erich
T1  - Synthesis and stereochemistry of new naphth[1,3]oxazino[3,2-a] benzazepine and naphth[1,3]oxazino[3,2-e]thienopyridine derivatives
JF  - Tetrahedron
N2  - Through the reactions of 1- or 2-naphthol and 4,5-dihydro-3H-benz[c]azepine or 6,7-dihydrothieno[3,2-c]pyridine, new aminonaphthol derivatives were prepared. The syntheses were extended by using N-containing naphthol analogues such as 5-hydroxyisoquinoline and 6-hydroxyquinoline. The ring closures of the novel bifunctional compounds were also achieved, resulting in new naphth[2,1-e][1,3]oxazines, naphth[1,2-e][1,3]oxazines, isoquinolino[5,6-e][1,3]oxazines and quinolino[5,6-e][1,3]oxazines. H-1 NMR spectra of the target heterocycles 16, 20 and 21 were sufficiently resolved to indentify the present stereochemistry; therefore, beside computed structures, spatial experimental (dipolar coupling-NOE) and computed (ring current effect of the naphthyl moiety-TSNMRS) NMR studies were employed. The studied heterocycles exist exclusively as S(14b),R(N), R(14b),S(N), and S(16b)S(N) isomers, respectively. The flexible moieties of the studied compounds prefer. (C) 2016 Elsevier Ltd. All rights reserved.
KW  - Modified Mannich reaction
KW  - Thienopyridine
KW  - Benzazepine
KW  - NMR spectroscopy
KW  - Stereochemistry
KW  - Theoretical calculations
Y1  - 2016
U6  - https://doi.org/10.1016/j.tet.2016.03.058
SN  - 0040-4020
VL  - 72
SP  - 2402
EP  - 2410
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - CHAP
A1  - Machumi, F.
A1  - Yenesew, Abiy
A1  - Midiwo, J. O.
A1  - Heydenreich, Matthias
A1  - Kleinpeter, Erich
A1  - Khan, S.
A1  - Tekwani, B. L.
A1  - Walker, L. A.
A1  - Muhammad, I
T1  - Antiparasitic and anticancer carvotacetone derivatives from Sphaeranthus bullatus
T2  - Planta medica : journal of medicinal plant and natural product research
Y1  - 2012
SN  - 0032-0943
VL  - 78
IS  - 11
SP  - 1201
EP  - 1202
PB  - Thieme
CY  - Stuttgart
ER  - 
TY  - JOUR
A1  - Kleinpeter, Erich
A1  - Heydenreich, Matthias
A1  - Shainyan, Bagrat A.
T1  - At the experimental limit of the NMR conformational analysis
BT  - Si-29 and C-13 NMR study of the conformational equilibrium of 1-phenyl-1-tert-butylsilacyclohexane
JF  - Organic letters
N2  - The low temperature (95 K) NMR study of 1-Ph-1-t-Bu-silacyclohexane (1) showed the conformational equilibrium to be extremely one-sided toward thePh(ax),t-Bueq conformer. The barrier to interconversion has been measured (4.2-4.6 kcal/mol) and the conformational equilibrium [Delta nu = 1990.64 ppm (Si-29), 618.9 ppm (C-13), 1-Ph-ax:1-Pheq = (95.6-96.6%):(3.4-4.4%), K = 25 +/- 3, Delta G degrees = -RT ln K = 0.58-0.63 kcal/mol] analyzed. The assignment and quantification of the NMR signals is supported by MP2 and DFT calculations.
Y1  - 2021
U6  - https://doi.org/10.1021/acs.orglett.0c03878
SN  - 1523-7060
SN  - 1523-7052
VL  - 23
IS  - 2
SP  - 405
EP  - 409
PB  - American Chemical Society
CY  - Washington
ER  -