Secondary compounds in the catalytic hydrogenation of enone and allylic alcohol prostaglandin intermediates: isolation, characterization, and X-ray crystallography

2019 ◽  
Vol 43 (20) ◽  
pp. 7582-7599
Author(s):  
Constantin I. Tănase ◽  
Florea Cocu ◽  
Constantin Drăghici ◽  
Anamaria Hanganu ◽  
Lucia Pintilie ◽  
...  
Keyword(s):  
Double Bond ◽  
Catalytic Hydrogenation ◽  
Secondary Compounds ◽  
Allylic Alcohol ◽  
Side Chain ◽  
X Ray ◽  
X Ray Crystallography

Hydrogenation of the double bond in the ω-side chain of prostaglandin intermediates: conditions to increase the yield and minimize the formation of secondary compounds.

scholarly journals Correction: Secondary compounds in the catalytic hydrogenation of enone and allylic alcohol prostaglandin intermediates: isolation, characterization, and X-ray crystallography

2019 ◽  
Vol 43 (20) ◽  
pp. 7882-7882
Author(s):  
Constantin I. Tănase ◽  
Florea Cocu ◽  
Constantin Drăghici ◽  
Anamaria Hanganu ◽  
Lucia Pintilie ◽  
...  
Keyword(s):  
Catalytic Hydrogenation ◽  
Secondary Compounds ◽  
Allylic Alcohol ◽  
X Ray ◽  
X Ray Crystallography

Correction for ‘Secondary compounds in the catalytic hydrogenation of enone and allylic alcohol prostaglandin intermediates: isolation, characterization, and X-ray crystallography’ by Constantin I. Tănase et al., New J. Chem., 2019, DOI: 10.1039/c9nj01186b.

scholarly journals NMR and X-ray studies of apetalic acid isolated from Calophyllum brasiliense and of its chiral amides

2021 ◽  
Author(s):  
Marie-Rose Van Calsteren ◽  
Ricardo Reyes-Chilpa ◽  
Chistopher K Jankowski ◽  
Fleur Gagnon ◽  
Simón Hernández-Ortega ◽  
...  
Keyword(s):  
Antimycobacterial Activity ◽  
Side Chain ◽  
Carboxyl Group ◽  
X Ray Diffraction ◽  
Rain Forests ◽  
X Ray ◽  
X Ray Crystallography ◽  
Calophyllum Brasiliense ◽  
Derivatives Of

The tropical tree Calophyllum brasiliense (Clusiaceae) grows in the rain forests from Brazil to Mexico. Its leaves, as well as those of other Calophyllum species, are rich sources of chromanone acids, such as apetalic acid, isoapetalic acid, and their derivatives. Apetalic acid has shown significant antimycobacterial activity. The biological activity of apetalic acid has been related to the configuration of three asymmetric centers and the stereochemistry of the molecule; however, the C-19 configuration in the acidic side chain has not been fully resolved. For this reason, the unequivocal determination of the absolute configuration by means of X-ray crystallography in a sample of unique homogeneous apetalic acid stereoisomer was the most important point to start this study. We prepared some chiral amides using the carboxyl group. We determined the C-19 stereochemistry of apetalic acid, and its specific chiral derivatives, using NMR, X-ray diffraction methods, and molecular mechanics. Finally, we observed that steric hindrance in the side chain of apetalic acid leads to restriction of rotation around the pivotal link C-10 and C-19 establishing chiral centers at C2(R), C3(S), and C19(R). We were able to separate derivatives of these two high-rotatory-barrier conformers of apetalic acid by forming diastereoisomeric amides with phenylglycine methyl ester having a chiral center at C-2’. Our results allowed the conclusion of the existence of atropisomerism in the apetalic acid molecule.

Heterometallische Cluster durch ligandunterstützte Metallfragmentkondensation / Heterometallic Clusters by Ligand Assisted Metal Fragment Condensation

1991 ◽  
Vol 46 (9) ◽  
pp. 1169-1176 ◽  
Author(s):  
Wolfgang Rohde ◽  
Gert Fendesak
Keyword(s):  
Double Bond ◽  
Chelate Complexes ◽  
Heterometallic Clusters ◽  
X Ray ◽  
X Ray Crystallography ◽  
Inert Solvent ◽  
Fragment Condensation ◽  
Olefinic Double Bond ◽  
High Yields ◽  
Iron Fragment

Dicobalt complexes of 3-vinylpropargylic alcohol derivatives react with biscyclooctenetricarbonyliron to give new chelate complexes of the iron tricarbonyl fragment with the olefinic double bond and the alcohol oxygen atom bound to the iron fragment. These compounds react upon heating in an inert solvent to give FeCo-alkynyl cluster complexes in high yields. One of these compounds has been structurally characterized by X-ray crystallography.

scholarly journals Reaction with Proteins of a Five-Coordinate Platinum(II) Compound

2019 ◽  
Vol 20 (3) ◽  
pp. 520 ◽  
Author(s):  
Giarita Ferraro ◽  
Tiziano Marzo ◽  
Maria Cucciolito ◽  
Francesco Ruffo ◽  
Luigi Messori ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Platinum Complexes ◽  
Rnase A ◽  
Side Chain ◽  
Planar Geometry ◽  
Ionization Mass ◽  
X Ray ◽  
X Ray Crystallography ◽  
Egg White Lysozyme ◽  
Square Planar

Stable five-coordinate Pt(II) complexes have been highlighted as a promising and original platform for the development of new cytotoxic drugs. Their interaction with proteins has been scarcely studied. Here, the reactivity of the five-coordinate Pt(II) compound [Pt(I)(Me) (dmphen)(olefin)] (Me = methyl, dmphen = 2,9-dimethyl-1,10-phenanthroline, olefin = dimethylfumarate) with the model proteins hen egg white lysozyme (HEWL) and bovine pancreatic ribonuclease (RNase A) has been investigated by X-ray crystallography and electrospray ionization mass spectrometry. The X-ray structures of the adducts of RNase A and HEWL with [Pt(I)(Me)(dmphen)(olefin)] are not of very high quality, but overall data indicate that, upon reaction with RNase A, the compound coordinates the side chain of His105 upon releasing the iodide ligand, but retains the pentacoordination. On the contrary, upon reaction with HEWL, the trigonal bi-pyramidal Pt geometry is lost, the iodide and the olefin ligands are released, and the metal center coordinates the side chain of His15 probably adopting a nearly square-planar geometry. This work underlines the importance of the combined use of crystallographic and mass spectrometry techniques to characterize, in detail, the protein–metallodrug recognition process. Our findings also suggest that five-coordinate Pt(II) complexes can act either retaining their uncommon structure or functioning as prodrugs, i.e., releasing square-planar platinum complexes as bioactive species.

scholarly journals Structural change of heme a side chain revealed by x-ray crystallography of bovine heart cytochrome c oxidase in the reduced state.

2001 ◽  
Vol 41 (supplement) ◽  
pp. S115
Author(s):  
K. Muramoto ◽  
S. Aonami ◽  
H. Aoyama ◽  
K. Shinzawa-Itoh ◽  
T. Ogura ◽  
...  
Keyword(s):  
Structural Change ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Side Chain ◽  
X Ray ◽  
X Ray Crystallography ◽  
Bovine Heart ◽  
Reduced State

Selective Bromochlorination of endo-1,4-Dibromotricyclo[5.2.1.02,6]deca-3,8-diene-5,10-dione 10-Ethylene Acetal at the Conjugated Carbon-Carbon Double Bond

1994 ◽  
Vol 47 (5) ◽  
pp. 963 ◽  
Author(s):  
RW Gable ◽  
KJ Parker ◽  
J Tsanaktsidis
Keyword(s):  
Double Bond ◽  
Thionyl Chloride ◽  
X Ray ◽  
Bromine Chloride ◽  
X Ray Crystallography ◽  
Carbon Double Bond ◽  
Selective Addition ◽  
Ethylene Acetal

Exposure of (1) to bromine in thionyl chloride/ dimethylformamide produced (5), the result of regio- and stereo-selective addition of bromine chloride across the carbonyl-conjugated double bond. The structure of (5) was determined by X-ray crystallography, and its mode of formation is discussed in terms of the carbonyl attack mechanism.

The geometry of 4-(1-ethoxyethylidene)-5-oxazolones and thiazolones: 1H and 13C studies and the crystal structure of 4-[(Z)-1-ethoxyethylidene]-2-phenyl-5-oxazolone

1985 ◽  
Vol 63 (12) ◽  
pp. 3618-3630 ◽  
Author(s):  
R. A. Bell ◽  
R. Faggiani ◽  
C. J. L. Lock ◽  
R. A. McLeod
Keyword(s):  
Crystal Structure ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Side Chain ◽  
Oxazole Ring ◽  
X Ray ◽  
X Ray Crystallography ◽  
Cell Dimensions ◽  
Ring Nitrogen ◽  
E And Z Isomers

A series of E and Z isomers of substituted 4-(1-ethoxyethylidene)-5-oxazolones and thiazolones have been prepared and their 1H and 13C spectra recorded. The vinylic methyl 1H chemical shifts showed minimal differences between E and Z isomers whereas the vinylic OCH21H signals differed by 0.15–0.43 ppm, with the Z isomer being consistently the more deshielded. Both vinylic methyl and OCH2 groups showed different 13C resonances for each isomer, with the Z isomers being the more deshielded. The Z geometry was conclusively defined for one isomer of 4-(1-ethoxyethylidene)-2-phenyl-5-oxazolone, 5, by X-ray crystallography and this was sufficient to assign the geometry of the remaining pairs of E and Z isomers. Oxazolone 5 has the space group P21/n and cell dimensions a = 9.219(3), b = 19.899(5), c = 7.459(1) Å, β = 118.01(2)°, and has four formula units in the unit cell. Intensities were measured with use of MoKα radiation and a Nicolet P3 diffractometer. The crystal structure was determined by standard methods and refined to R1 = 0.0709, R2 = 0.0696 based on 1419 independent reflections. The molecule is essentially planar and most bond lengths and angles are normal. Exceptions are the very short C(olefin)—O(ether) bond (1.339(4) Å) and the large ether C—O—C angle (122.1(3)°) caused by extreme delocalization in the O(ether)CCCO(carbonyl) system. The planarity causes a number of strong intramolecular repulsive interactions, causing an exceptionally small external olefin angle, O(ether)CC(methyl), of 108.1(4)°. The ethoxyl side chain of 5 adopts a conformation in the solid state which places the methylene of the OCH2 group adjacent to the oxazole ring nitrogen. This conformation is proposed to persist in solution phases and is consistent with the observed 13C chemical shifts and known γ and δ substituent effects.

scholarly journals Polymerization of Propene with Modified Constrained Geometry Complexes. Double-Bond Isomerization in Pendant Alkenyl Groups Attached to Cyclopentadienyl Ligands

2003 ◽  
Vol 68 (6) ◽  
pp. 1119-1130 ◽  
Author(s):  
Oetze K. B. Staal ◽  
Dirk J. Beetstra ◽  
Andries P. Jekel ◽  
Bart Hessen ◽  
Jan H. Teuben ◽  
...  
Keyword(s):  
Double Bond ◽  
Spectroscopic Data ◽  
Catalyst Activity ◽  
X Ray ◽  
X Ray Crystallography ◽  
Molecular Weights ◽  
Constrained Geometry ◽  
Internal Position ◽  
Moderate Effect ◽  
C Nmr

Polymerization of propene with dimethylsilylene-bridged (amidocyclopentadienyl)dichlorotitanium(IV) complexes [TiCl2{η5-1-(t-BuSiMe2N-κN)-2,3,4-Me3-5-R-C5}], where R = Me (1), H (2), Ph (3), 4-fluorophenyl (4), but-2-en-2-yl (5), and butyl (6), combined with excess methylaluminoxane revealed a moderate effect of the substituent R on the catalyst activity and the molecular weight of polypropene. The asymmetric substitution in the position adjacent to the bridging carbon atom resulted in polymer yields decreasing in the order 1 > 6 > 3 ≈ 5 > 4 > 2 while polymers with the molecular weights (Mw) close to 2.5 × 105 for 1, 3, and 4, 1.5 × 105 for 5 and 6, and 7.5 × 104 for 2 were obtained. The 13C NMR analysis of the polymers has shown that atactic polypropene is slightly enriched with syndiotactic triads for all the catalysts. Investigation of the crystal structure of 5 by X-ray crystallography revealed that the double bond in but-3-en-2-yl had shifted to an internal position to give the isomeric, but-2-en-2-yl-substituted complex. Likewise, the spectroscopic data for complex 7 prepared from the ligand containing but-3-en-1-yl substituent, indicate the absence of terminal double bond.

A Convenient Synthesis of Tetrasubstituted Pyrazoles from Nitrile Imines and 2-(Thioxothiazolidin-5-ylidene)acetates

Synlett ◽  
2018 ◽  
Vol 29 (07) ◽  
pp. 918-921 ◽  
Author(s):  
Issa Yavari ◽  
Zohreh Taheri ◽  
Maryam Naeimabadi ◽  
Samira Bahemmat ◽  
Mohammad Halvagar
Keyword(s):  
Double Bond ◽  
Dipolar Cycloaddition ◽  
Pyrazole Derivatives ◽  
X Ray ◽  
X Ray Crystallography ◽  
Hydrazonoyl Chlorides ◽  
Convenient Synthesis ◽  
Nitrile Imines ◽  
Fast Access

Alkyl 2-(3-alkyl-4-oxo-2-thioxothiazolidin-5-ylidene)acetates react with hydrazonoyl chlorides in the presence of triethylamine to ­afford tetrasubstituted pyrazole derivatives. Formally, this transformation is regarded as a 1,3-dipolar cycloaddition of the exocyclic carbon–carbon double bond of the thioxothiazolidine derivatives with nitrile imines generated in situ. This efficient method provides fast access to a range of structurally diverse pyrazoles. The structure of a typical product is confirmed by X-ray crystallography.

A Concise Synthesis of 24,25-Dihydro-6-epi-Monanchosterol A

Synlett ◽  
2021 ◽  
Author(s):  
Hans-Günther Schmalz ◽  
Ömer Taspinar ◽  
Vladimir Kjartan Stojadinovic ◽  
Jörg-Martin Neudörfl
Keyword(s):  
Double Bond ◽  
Title Compound ◽  
Protecting Group ◽  
Structural Analogue ◽  
X Ray ◽  
X Ray Crystallography ◽  
Anti Inflammatory ◽  
Aldol Addition ◽  
Optimized Conditions

AbstractWe report the first synthetic entry to a steroid with an unusual bicyclo[4.3.1]dec-3-en-10-one A/B ring substructure as a close structural analogue of the anti-inflammatory monanchosterols. Under optimized conditions, regioselective cis-dihydroxylation of the Δ5-double bond of 7-dehydrocholesterol and subsequent Criegee oxidation yields the corresponding 5,6-seco-steroid as a pure Z-isomer which upon treatment with K2CO3 in MeOH diastereoselectively affords 24,25-dihydro-6-epi-monanchosterol A through intramolecular aldol addition (cyclization). The developed three-step sequence proceeds in 17% overall yield without the need of any protecting group. The title compound was characterized by X-ray crystallography.

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