Stereoisomeric chiral 2,9-diazabicyclo[4.4.0.]decane-3,10-diones as models of dipeptide grouping: Synthesis, X-ray, IR, NMR and cd studies

1984 ◽  
Vol 49 (3) ◽  
pp. 712-742 ◽  
Author(s):  
Karel Bláha ◽  
Ahmed M. Farag ◽  
Dick VAN DER Helm ◽  
M. Bilayet Hossain ◽  
Miloš Buděšínský ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Stereospecific Synthesis ◽  
Cd Spectra ◽  
X Ray Diffraction ◽  
Relative Configuration ◽  
X Ray ◽  
H Nmr ◽  
Chemical Correlation ◽  
Cd Studies ◽  
C Nmr

Synthesis of the title optically active bicyclic dilactams I and II with cis- and trans-annelation of rings is described. The stereospecific synthesis started from (2R)-2-benzamido-2-(4-oxocyclohexyl)acetic acid ((-)-VI) whose absolute configuration was determined by chemical correlation with the known (2R)-2-amino-(4-hydroxyphenyl)acetic acid ((-)-IIIb). Relative configuration at the bridgehead atoms in I and II was assigned by 1H and 13C NMR spectroscopy and confirmed by X-ray diffraction analysis which showed the detailed conformation in crystal. According to the 1H NMR spectra in solution the trans-isomer II has the same configuration as in crystal whereas the cis-isomer I exists in two forms one of which is identical with that in crystal. This conformational analysis agrees also with the IR spectra, detecting an intramolecularly hydrogen-bonded conformation for IIbut no hydrogen bond for I. The CD spectra of both lactams were successfully interpreted using the exciton theory in the π-π region where it reflects the differences in the angles Φ and ψ (for I Φ = 110°, ψ = -143°; forII Φ = -145°, ψ = 162°). In the n-π transition region the interpretation was based on the quadrant rule and also inherent non-planarity of one of the amide groups in II.

An unusual reaction of a bridged triterpenoid α-diketone with acetic anhydride

1991 ◽  
Vol 56 (12) ◽  
pp. 2917-2935 ◽  
Author(s):  
Eva Klinotová ◽  
Václav Křeček ◽  
Jiří Klinot ◽  
Miloš Buděšínský ◽  
Jaroslav Podlaha ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Nmr Spectroscopy ◽  
Acetic Anhydride ◽  
Spectral Methods ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mild Conditions ◽  
Condensation Products ◽  
Unsaturated Lactones ◽  
C Nmr

3β-Acetoxy-21,22-dioxo-18α,19βH-ursan-28,20β-olide (IIIa) reacts with acetic anhydride in pyridine under very mild conditions affording β-lactone IVa and γ-lactones Va and VIIa as condensation products. On reaction with pyridine, lactones Va and VIIa undergo elimination of acetic acid to give unsaturated lactones VIIIa and IXa, respectively. Similarly, the condensation of 20β,28-epoxy-21,22-dioxo-18α,19βH-ursan-3β-yl acetate (IIIb) with acetic anhydride leads to β-lactone IVb and γ-lactone Vb; the latter on heating with pyridine affords unsaturated lactone VIIIb and 21-methylene-22-ketone Xb. The structure of the obtained compounds was derived using spectral methods, particularly 1H and 13C NMR spectroscopy; structure of lactone IVa was confirmed by X-ray diffraction.

scholarly journals Tautomerisation in 1-(4-Methylphenylazo)naphthalen-2-ol and 2-(4-Methylphenylazo)-4-methylphenol: A Crystallographic and 13C{1H}NMR Study

1999 ◽  
Vol 23 (3) ◽  
pp. 178-179
Author(s):  
Wendy I. Cross ◽  
Kevin R. Flower ◽  
Robin G. Pritchard
Keyword(s):  
Acetic Acid ◽  
Nmr Spectroscopy ◽  
Resonant Frequency ◽  
X Ray Diffraction ◽  
X Ray ◽  
H Nmr ◽  
Nmr Study ◽  
Acetic Acid Esters ◽  
Acid Esters ◽  
Equivalent Carbon

The acetic acid esters of 1-(4-methylphenylazo)naphthalen-2-ol 1 and 2-(4-methylphenylazo)-4-methylphenol 3 are prepared and characterised by single crystal X-ray diffraction studies and 13C{1H}NMR spectroscopy; the position of the C(2)13C resonance for the ester is used to predict the position of resonant frequency of the equivalent carbon in the parent alcohols and hence, calculate the position of the azo-hydrazone equilibrium in these compounds.

scholarly journals A series of Mn(i) photo-activated carbon monoxide-releasing molecules with benzimidazole coligands: synthesis, structural characterization, CO releasing properties and biological activity evaluation

RSC Advances ◽  
2019 ◽  
Vol 9 (36) ◽  
pp. 20505-20512 ◽  
Author(s):  
Mixia Hu ◽  
YaLi Yan ◽  
Baohua Zhu ◽  
Fei Chang ◽  
Shiyong Yu ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Biological Activity ◽  
Activated Carbon ◽  
Fluorescence Spectroscopy ◽  
Single Crystal ◽  
Structural Characterization ◽  
X Ray Diffraction ◽  
X Ray ◽  
H Nmr ◽  
C Nmr

Five Mn(i) photo-activated carbon monoxide-releasing molecules were synthesized by reactions of MnBr(CO)5 with L1–L4, and characterized via single crystal X-ray diffraction, 1H-NMR, 13C-NMR, IR, UV-vis and fluorescence spectroscopy.

scholarly journals New Synthetic Routes for 1-Benzyl-1,4,7,10-tetraazacyclododecane and 1,4,7,10-Tetraazacyclododecane-1-acetic Acid Ethyl Ester, Important Starting Materials for Metal-coded DOTA-Based Affinity Tags

2007 ◽  
Vol 62 (3) ◽  
pp. 397-406 ◽  
Author(s):  
Stephan W. Kohl ◽  
Katharina Kuse ◽  
Markus Hummert ◽  
Herbert Schumann ◽  
Clemens Mügge ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Ethyl Ester ◽  
Nmr Spectra ◽  
Acid Ethyl Ester ◽  
Affinity Tags ◽  
X Ray ◽  
H Nmr ◽  
Synthetic Routes ◽  
New Compounds ◽  
C Nmr

Two improved routes to synthesize 1-benzyl-1,4,7,10-tetraazacyclododecane (6) and 1,4,7,10- tetraazacyclododecane-1-acetic acid ethyl ester (11) are described as well as the synthesis of 1-{2-[4-(maleimido-N-propylacetamidobutyl)amino]-2-oxoethyl}-1,4,7,10-tetraazacyclododecane- 4,7,10-triacetic acid (17) and its Y, Ho, Tm, and Lu complexes. The 1H and 13C NMR spectra of the new compounds as well as the single crystal X-ray structure analyses of the intermediates 4-benzyl-1,7-bis(p-toluenesulfonyl)diethylenetriamine (3) and 1,4,7-tris(p-toluenesulfonyl)diethylenetriamine (7) are reported and discussed. The rare earth complexes of 17 have been characterized by 1H NMR spectroscopy and MALDI-TOF mass spectrometry.

Microbial Transformation of Glycyrrhetinic Acid by Colletotrichum lini AS3.4486

2015 ◽  
Vol 1120-1121 ◽  
pp. 877-881
Author(s):  
Chao Jun He ◽  
Yu Min Yang ◽  
Kong Yang Wu
Keyword(s):  
Single Crystal ◽  
Microbial Transformation ◽  
Glycyrrhetinic Acid ◽  
Conversion Product ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
X Ray ◽  
H Nmr ◽  
Sole Product ◽  
C Nmr

The biotransformation of 18β-glycyrrhetinic acid by Colletotrichum lini AS3.4486 was investigated. The conversion reaction was carried out for 72h, and the sole product was isolated by column chromatography and elucidated as 7β,15α-dihydroxy-18β-glycyrrhetinic acid by HR-ESI-MS, 1H-NMR , 13C-NMR and single–crystal X-ray diffraction. The crystal of the conversion product belongs to orthorhombic, space group P212121 with 11.828(1), 13.213(2), 19.606(2) Å , V = 3064.0 Å3, Z = 4. This study povides a new method for the synthesis of 7β,15α-dihydroxy-18β-glycyrrhetinic acid.

β-Hydroxydithiozimtsäurederivate als Liganden. Synthese und Charakterisierung neuartiger 1,1-Ethendithiolato- und O,S-Chelatkomplexe / Derivatives of β -Hydroxydithiocinnamic Acids as Ligands. Syntheses and Characterisation of Novel 1,1-Ethenedithiolato and O,S-Chelate Complexes

2007 ◽  
Vol 62 (3) ◽  
pp. 475-482 ◽  
Author(s):  
Karsten Schubert ◽  
Helmar Görls ◽  
Wolfgang Weigand
Keyword(s):  
Bidentate Ligand ◽  
Molecular Structures ◽  
X Ray Diffraction ◽  
Chelate Complexes ◽  
X Ray ◽  
H Nmr ◽  
Hexyl Ester ◽  
Elemental Analyses ◽  
Derivatives Of ◽  
C Nmr

Starting from 4-bromoacetophenone 1, the 4-bromo-β -hydroxydithiocinnamic acid 2 and the 4-bromo-β -hydroxydithiocinnamic acid hexyl ester 3 were prepared using carbon disulfide and potassium-tert-butylate as a base. Acting as a ligand, the acid gives 1,1-ethenedithiolato complexes with (Ph3P)2Pt(II) (4a), (Et3P)2Pt(II) (4b), dppePt(II) (4c), (Ph3P)2Pd(II) (4d), dppePd(II) (4e), and dppeNi(II) (4f). In contrast to the acid, the deprotonated ester 3 forms a monoanionic bidentate ligand. [O,S] Complexes of Pt(II) (5a), Pd(II) (5b) and Ni(II) (5c) were obtained. All complexes have been fully characterised using 1H NMR, 13C NMR and 31P NMR spectroscopy, mass spectrometry, infrared spectroscopy and elemental analyses. The molecular structures of the complexes 4b and 5a - 5c were determined by X-ray diffraction analyses.

(3E)-5-Hydroxy-3-[5-(hydroxymethyl)furan-2-ylmethylene]-1-benzofuran-2(3H)-one

2007 ◽  
Vol 63 (11) ◽  
pp. o4354-o4354
Author(s):  
Hong-Yan Ma ◽  
Ji Shi ◽  
Chang-Hong Wang ◽  
Zheng-Tao Wang
Keyword(s):  
Hydrogen Bonds ◽  
Spectroscopic Data ◽  
Furan Ring ◽  
Crystallographic Analysis ◽  
Relative Configuration ◽  
X Ray ◽  
H Nmr ◽  
Compound C ◽  
A Chain ◽  
C Nmr

The title compound, C14H10O5, was isolated from Senecio cannabifolius Less var. integrifolius aqueous extract. The structure was elucidated on the basis of spectroscopic data, including MS, 1H NMR and 13C NMR, and the relative configuration was confirmed by X-ray crystallographic analysis. The benzofuran ring is almost coplanar with the furan ring [dihedral angle = 10.47 (15)°]. A chain is formed through supramolecular R 2 2(10) synthons and three-centre hydrogen bonds.

Structure of isosilerolide, relative and absolute configuration of silerolide and lasolide - Sesquiterpenic lactones of new stereoisomeric type of eudesmanolides

1986 ◽  
Vol 51 (4) ◽  
pp. 903-929 ◽  
Author(s):  
Miroslav Holub ◽  
Miloš Buděšínský ◽  
Zdenka Smítalová ◽  
David Šaman ◽  
Urszula Rychłewska
Keyword(s):  
Absolute Configuration ◽  
X Ray Diffraction ◽  
X Ray ◽  
H Nmr ◽  
Nmr Data ◽  
Chemical Correlation ◽  
The Absolute

On the basis of spectroscopic, particularly 1H NMR data, isosilerolide was assigned structure I, including the absolute configuration. The structure was confirmed by X-ray diffraction. Isosilerolide represents a new stereoisomeric type of natural eudesmanolides, characterized as 5βH, 6αH, 7αH, 10αCH3-eudesman-6,12-olide. As shown by the chemical correlation of isosilerolide (I) with silerolide (III) and lasolide (X), the latter two natural lactones belong to this stereoisomeric group of eudesmanolides. Analysis of models and 1H NMR data shows that structures of some eudesman-6,12-olides, published by other authors, should be corrected.

On Attempts to Synthesize Lanthanide Complexes of the Dianionic Fluorenyl-alkoxo Ligand [C13H8-cyclo-C6H10-O]2-. Crystal Structure of (C13H9-cyclo-C6H10-O)LaI2(DME)2

2003 ◽  
Vol 58 (5) ◽  
pp. 389-394 ◽  
Author(s):  
Alexander A. Trifonov ◽  
Mikhail N. Bochkarev ◽  
Herbert Schumann ◽  
Sebastian Dechert
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Ir Spectra ◽  
Single Crystal ◽  
Lanthanide Complexes ◽  
X Ray Diffraction ◽  
X Ray ◽  
H Nmr ◽  
Elemental Analyses ◽  
C Nmr

Racemic trans-2-(9(H)-fluoren-9-yl)cyclohexanol, C13H9-cyclo-C6H10-OH (1), reacts with two equivalents of potassium naphthalenide in THF to give the dipotassium salt [C13H8-cyclo-C6H10-O]- K2(THF) (2). Recrystallization of 2 from pyridine affords the solvent free salt [C13H8-cyclo-C6H10- O]K2 (3). The reactions of LaI3(THF)4 with one equivalent of 2 or of YbI2(THF)2 with equimolar amounts of 2 produce the alkoxolanthanum diiodide (C13H9-cyclo-C6H10-O)LaI2(DME)2 (4) and the ytterbium dialkoxide (C13H9-cyclo-C6H10-O)2Yb(THF)0.5(5), respectively. [(Me3Si)2N]3Y reacts with three equivalents of 1 with elimination of hexamethyldisilazane and formation of the yttrium trialkoxide (C13H9-cyclo-C6H10-O)3Y (6). The compounds 2 to 5 were characterized by elemental analyses, 1H NMR, 13C NMR and IR spectra. The molecular structure of 4 was determined by single crystal X-ray diffraction.

Stereochemistry of the Bucherer–Bergs and Strecker reactions of tropinone, cis-bicyclo[3.3.0]octan-3-one and cis-3,4-dimethylcyclopentanone

1979 ◽  
Vol 57 (12) ◽  
pp. 1456-1461 ◽  
Author(s):  
Gregorio G. Trigo ◽  
Carmen Avendaño ◽  
Emilia Santos ◽  
John T. Edward ◽  
Sin Cheong Wong
Keyword(s):  
Carbonyl Group ◽  
Equatorial Position ◽  
X Ray Diffraction ◽  
X Ray ◽  
H Nmr ◽  
Strecker Reaction ◽  
C Nmr

The tropane-3-spiro-5′-hydantoin (α isomer) obtained from tropinone by the Bucherer–Bergs reaction has been shown by 13C nmr and X-ray diffraction studies to have the 4′-carbonyl group in the equatorial position; the β isomer, obtained via the Strecker reaction, has this group axial. The results of these two reactions on cis-bicyclo[3.3.0]octan-3-one and on cis-3,4-dimethylcyclopentanone show, on the basis of the 1H nmr, 13C nmr, and X-ray diffraction studies of the products, a stereochemical course related to the preferred conformation of the cyclopentane rings.

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