scholarly journals Diastereoselective anodic hetero- and homo-coupling of menthol-, 8-methylmenthol- and 8-phenylmenthol-2-alkylmalonates

2017 ◽  
Vol 13 ◽  
pp. 33-42 ◽  
Author(s):  
Matthias C Letzel ◽  
Hans J Schäfer ◽  
Roland Fröhlich
Keyword(s):  
Structure Analysis ◽  
Malonic Acid ◽  
Platinum Electrodes ◽  
Chiral Auxiliaries ◽  
X Ray ◽  
Radical Coupling ◽  
Nmr Data ◽  
Stereogenic Centers ◽  
Malonic Acid Derivatives ◽  
C Nmr

Diastereoselective radical coupling was achieved with chiral auxiliaries. The radicals were generated by anodic decarboxylation of five malonic acid derivatives. These were prepared from benzyl malonates and four menthol auxiliaries. Coelectrolyses with 3,3-dimethylbutanoic acid in methanol at platinum electrodes in an undivided cell afforded hetero-coupling products in 22–69% yield with a diastereoselectivity ranging from 5 to 65% de. Electrolyses without a coacid led to diastereomeric homo-coupling products in 21–50% yield with ratios of diastereomers being 1.17:2.00:0.81 to 7.03:2.00. The stereochemistry of the new stereogenic centers was confirmed by X-ray structure analysis and 13C NMR data.

scholarly journals NMR, X-Ray and MS Investigations of Ethyl 2-Aroyl-and Ethyl 2-Arylcarbamoyl-4,5- dimethyl-1,2,3,6-tetrahydropyridazine-1- carboxylates: Flexible Multidentate Ligands

1999 ◽  
Vol 23 (3) ◽  
pp. 186-187
Author(s):  
Erkki Kolehmainen ◽  
Katri Laihia ◽  
Maija Nissinen ◽  
Kalevi Pihlaja ◽  
Alexander Perjéssy ◽  
...  
Keyword(s):  
Structure Analysis ◽  
Multidentate Ligands ◽  
X Ray ◽  
C Nmr

The 1H and 13C NMR spectral assignments of ethyl 2-aroyl-4,5-dimethyl-1,2,3,6-tetrahydropyridazine-1-carboxylates (1a-1h) and ethyl 2-arylcarbamoyl-4,5-dimethyl-1,2,3,6-tetrahydropyridazine-1-carboxylates (2a-2k) are given based on DQF COSY, 1H,13C HMQC and 1H,13C HMBC-measurements; the dynamics of the tetrahydropyridazine ring has been studied by 1H, 1H EXSY-technique and the structure of one congener (4′-methylphenyl-derivative, 2a) has been confirmed by X-ray structure analysis.

Sur une nouvelle méthode de synthèse de δ-lactones cyclopenténiques

1986 ◽  
Vol 64 (4) ◽  
pp. 831-836 ◽  
Author(s):  
Jean Claude Caille ◽  
Michel Farnier ◽  
Roger Guilard ◽  
André Aubry ◽  
Claude Lecomte
Keyword(s):  
Mass Spectrometry ◽  
Carbon Atom ◽  
X Ray ◽  
Nmr Data ◽  
C Nmr

Synthesis of two cyclopentenic δ-lactones, 1,3,4,4a,5,6-hexahydrocyclopenta[c]pyran-1-one and its analogue possessing a cyclopentenyl group bonded to the carbon atom 4a is described, starting from the cyclopentanone or cyclopentylidene cyclopentanone. The remarkable reactivity of the tosylhydrazones allows transformation of these compounds into substituted cyclopentenes, which lead to δ-lactones by cyclization. The conditions of cyclization depend on the nature of the cyclopentanone. The structure of the two δ-lactones is established by 1H and 13C nmr data, mass spectrometry, and, in one case, by X-ray analysis.

Zur Darstellung und Struktur des 1.3-Dichloro-5-N.N-dimethylamino-1.3-dithia-2.4.6-triazins / Synthesis and Structure of 1,3-Dichloro-5-N,N-dimethylamino-1,3-dithia-2,4,6-triazine

1983 ◽  
Vol 38 (3) ◽  
pp. 347-349 ◽  
Author(s):  
Herbert W. Roesky ◽  
Pierre Schäfer ◽  
Mathias Noltemeyer ◽  
George M. Sheldrick
Keyword(s):  
Structure Analysis ◽  
Nmr Spectra ◽  
Membered Ring ◽  
Monoclinic Space Group ◽  
Space Group ◽  
X Ray ◽  
Cl Atoms ◽  
C Nmr

Abstract The six membered ring of composition (CH3)2NCN3S2Cl2 3 a was prepared from N,N-dimethylguanidinhydrochloride and trithiadiazindichloride. 3 a was characterized on the basis of mass, 1H, 13C NMR spectra and X-ray structure analysis. Crystals of 3 a are monoclinic, space group P21/c, with a = 660.3(6), b = 834.5(7), c = 1774.7(15) pm, β = 112.83(6)° and Z = 4. The C2N unit lies approximately in the plane of the [-CNSNSN-] ring, with both Cl atoms on the same side of the ring.

Tautomerism in 3{5}-(dimethoxyphenyl)pyrazoles

1996 ◽  
Vol 52 (4) ◽  
pp. 746-752 ◽  
Author(s):  
M. A. Halcrow ◽  
H. R. Powell ◽  
M. J. Duer
Keyword(s):  
Hydrogen Bond ◽  
Nmr Spectroscopy ◽  
Solvate Water Molecule ◽  
X Ray ◽  
Nmr Data ◽  
Tautomeric Forms ◽  
Oxygen Donor ◽  
Intramolecular Hydrogen ◽  
Pyridinic N ◽  
C Nmr

The single-crystal X-ray structures of 3{5}-(2′,5′-dimethoxyphenyl)pyrazole (HI) and the hemihydrate of 3 {5}-(3/,4′-dimethoxyphenyl)pyrazole (IV) have been determined. Compound (HI) exists purely as the 5-substituted prototropomer in the crystal; the pyrazole pyrollic N—H proton is involved in a three-way hydrogen bond, involving an intramolecular contact with a methoxy oxygen donor and an intermolecular interaction to the pyridinic N atom of a neighbouring molecule, forming discrete hydrogen-bonded dimers. There is no evidence of degenerate proton transfer within the dimeric units from CPMAS 13C NMR spectroscopy, in contrast to other known pyrazoles that associate in this manner. In (IV).1/2H2O, however, the pyrrolic proton is disordered over both N(1) and N(2) via hydrogen bonding to the solvate water molecule. CPMAS 13C NMR spectroscopy shows that the prototropic disorder in (IV).1/2H2O is static at temperatures up to 370 K. Solution 1H and 13C NMR data in DMSO-d 6 show that for both (HI) and (IV) the 3- and 5-substituted tautomeric forms are similarly populated in this solvent, suggesting both that the intramolecular hydrogen bond in (HI) has been disrupted and that the two tautomers of (HI) and (IV) are close in energy.

Pseudozoanthoxanthins from gold coral

1979 ◽  
Vol 57 (13) ◽  
pp. 1707-1711 ◽  
Author(s):  
Robert E. Schwartz ◽  
Mark B. Yunker ◽  
Paul J. Scheuer ◽  
Tor Ottersen
Keyword(s):  
Deep Water ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nmr Data ◽  
Derivatives Of ◽  
C Nmr

From a deep water Pacific zoanthid, Gerardia sp., we have isolated two new fluorescent nitrogenous pigments, derivatives of tetrazacyclopentazulene. The first was characterized by uv, 1H and 13C nmr data, and by X-ray diffraction; the second by interconversion.

Oxidative coupling of naphtho-9-crown-3 ether: X-ray crystal structure and solution and solid-state NMR analysis of the dimer

2001 ◽  
Vol 79 (10) ◽  
pp. 1505-1510 ◽  
Author(s):  
G W Buchanan ◽  
M F Rastegar ◽  
G PA Yap ◽  
A Moghimi ◽  
M Ghandi
Keyword(s):  
Solid State ◽  
Oxidative Coupling ◽  
Solid State Nmr ◽  
Nmr Analysis ◽  
Oxidative Dimerization ◽  
Nmr Spectrum ◽  
X Ray ◽  
Nmr Data ◽  
Group A ◽  
C Nmr

Treatment of naphtho-9-crown-3 ether with FeCl3 and aqueous H2SO4 generates bis-naphtho-9-crown-3 ether in ca. 30% yield. This compound crystallizes in the monoclinic P21/n space group; a = 9.2004(9), b = 18.0868(17), and c = 13.2078(13) Å, β = 97.799(2)° and Z = 4. 1H and 13C NMR data have been obtained in solution, and the solid-state 13C NMR spectrum is included for comparison. A chemical shift range of ca. 12 ppm has been found for the oxygenated aliphatic carbons in the solid state, in contrast to the 3 ppm range in the solution 13C NMR spectrum. These results are discussed in terms of the torsional environments of the carbon sites in the crystal structure.Key words: crown ether, stereochemistry, oxidative dimerization.

The Structure And Tautomerism Of Cyameluric Acid*

2006 ◽  
Vol 61 (8) ◽  
pp. 975-978 ◽  
Author(s):  
Jörg Wagler ◽  
Nadia E. A. El-Gamel ◽  
Edwin Kroke
Keyword(s):  
Single Crystal ◽  
Keto Form ◽  
X Ray ◽  
Nmr Data ◽  
Almost All ◽  
Derivatives Of ◽  
Theoretical Results ◽  
C Nmr

The single crystal X-ray structure of the DMSO solvate of cyameluric acid C6N7O3H3 ·3DMSO, 2b’ has been determined. The results show that the most stable tautomer of solid cyameluric acid is the tri-keto form 2b with C3h symmetry. 1H and 13C NMR data indicate that this isomer is also present in solution, with slow interchange of the N-H protons. This confirms previous theoretical results although almost all derivatives reported in the literature are derivatives of the tri-hydroxy tautomer 2a

Reactivity of diosmacycles: complementary syntheses and structure Of [(µ-η1,η2-CHCH2)OS2(CO)8][BF4]

1995 ◽  
Vol 73 (7) ◽  
pp. 1003-1009 ◽  
Author(s):  
R.G. Ball ◽  
Gong Y. Kiel ◽  
William A. Kiel ◽  
Josef Takats ◽  
Friedrich-Wilhelm Grevels
Keyword(s):  
Solid State ◽  
Traditional View ◽  
Cationic Complex ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
X Ray ◽  
Excellent Yield ◽  
Nmr Data ◽  
Hydride Abstraction ◽  
C Nmr

The vinyl-bridged cationic complex, [(µ-CHCH2)Os2(CO)8][BF4] (3), is obtained readily and in excellent yield either via hydride abstraction from octacarbonyl diosmacyclobutane, (µ-η1,η1-CH2CH2)Os2(CO)8 (1), or via protonation of octacarbonyl diosmacyclobutene, (µ-η1,η1-CHCH)Os2(CO)8 (2). It is argued that the 1H and 13C NMR data of complex 3 are consistent with the traditional view of bonding in µ-alkenyl complexes, involving substantial σ,π donation. The solid state X-ray structure of the complex lends support for this formulation. Complex 3 crystallizes in the orthorhombic space group, P212121, with a = 12.128(2) Å, b = 14.151(3) Å, c = 9.248(3) Å, V = 1587 Å3, and Z = 4. The final R and Rw values are 0.032 and 0.038, respectively. Keywords: µ-vinyl, diosmacycles, X-ray structure.

Binuclear Fulvalene and Bis(cyclopentadienyl)methane Halfsandwich Complexes of Manganese and Rhenium Containing Tetrahydrothiophene Ligands. X-Ray Structure Analysis of {(CO)2Mn[C5H4-C5H4]Mn(CO)2}(μ-SC4H8)

1993 ◽  
Vol 48 (2) ◽  
pp. 161-170 ◽  
Author(s):  
Max Herberhold ◽  
Martin Biersack ◽  
Thomas E. Bitterwolf ◽  
Arnold L. Rheingold
Keyword(s):  
Molecular Structure ◽  
Ir Spectra ◽  
Structure Analysis ◽  
Nmr Spectra ◽  
X Ray ◽  
Carbonyl Ligands ◽  
Tetrahydrofuran Solution ◽  
C Nmr

AbstractThe photo-induced substitution of carbonyl ligands in the binuclear cyclopentadienyl-type complexes (CO)3M[C5H4(CH2)nC5H4]M(CO)3 (n = 0 (fulvalene), M = Mn (1) and Re (2); n = 1 (bis(cyclopentadienyl)methane), M = Mn (3) and Re (4)) has been studied in the presence of tetrahydrothiophene, SC4H8 (tht). Photodecarbonylation of 1 - 4 in tetrahydrofuran solution leads to solvent-stabilized intermediates which react with tht in the dark to give monosubstituted derivatives (CO)3M[C5H4(CH2)nC5H4]M(CO)2(tht) (1a - 4a). In the case of M = Mn, thtbridged compounds {(CO)2Mn[C5H4(CH2)nC5H4]Mn(CO)2}(μ-tht) (n = 0 (1b) and n = 1 (3b)) are also obtained which are the exclusive products of the photolysis of 1 and 3 in benzene in the presence of tht. Photodecarbonylation of 1 - 4 in neat tetrahydrothiophene produces disubstituted derivatives in the case of manganese, (tht)(CO)2Mn[C5H4(CH2)nC5H4]Mn(CO)2(tht) (n = 0 (1c) and n = 1 (3c)), whereas only the monosubstituted complexes 2a and 4a could be isolated in the case of rhenium. The molecular structure of the tht-bridged fulvalene complex 1b has been determined by an X-ray structure analysis. A special reaction of dimethyl disulfane with the photolyzed tetrahydrofuran solution of 2 leads to the bis(methylthiolato) compound (CO)3Re[C5H4- C5H4]Re(CO)(SMe)2 (5). The new complexes were characterized by their IR spectra v(CO) and their 1H and 13C NMR spectra.

[(Dimethylamino)methyl]ferrocene as an Amine Ligand: Study of the Bonding and X-Ray Crystal and Molecular Structure of the Pentacarbonyl{[(dimethylamino)methyl]ferrocene}tungsten Complex

2002 ◽  
Vol 67 (2) ◽  
pp. 228-234 ◽  
Author(s):  
Axel Fischer ◽  
Frank T. Edelmann ◽  
Klaus Jacob ◽  
Ivan Pavlík ◽  
Martin Pavlišta
Keyword(s):  
Molecular Structure ◽  
Single Crystal ◽  
Crystal And Molecular Structure ◽  
X Ray Diffraction ◽  
Amine Nitrogen ◽  
X Ray ◽  
Nmr Data ◽  
Amine Ligand ◽  
C Nmr

The heterodinuclear complex [W(CO)5(Me2NCH2Fc)] (Fc = ferrocenyl) (1) resulting from the reaction of [(dimethylamino)methyl]ferrocene (2) and [W(CO)6] was studied by single-crystal X-ray diffraction. Its molecular structure confirms the coordination of the amine nitrogen in 2 to tungsten (d(W-N) = 2.359(5) Å) and reveals its trans-influence in the W(CO)5 moiety. The structure is discussed in relation to several previously referred spectroscopic (IR, UV-VIS, 13C NMR) data.

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