Orthoamide, LVII [1]. Lassen sich aromatische Aldehyde nach Fries aus Arylformiaten hersteilen? / Orthoamides, LVII [1]. Can Aromatic Aldehydes be Prepared from Aryl Formates via the Fries Rearrangement?

2001 ◽  
Vol 56 (11) ◽  
pp. 1178-1187 ◽  
Author(s):  
Georg Ziegler ◽  
Erwin Haug ◽  
Wolfgang Frey ◽  
Willi Kantlehner
Keyword(s):  
Crystal Structure ◽  
Formic Acid ◽  
Structure Analysis ◽  
Good Yield ◽  
Lewis Acids ◽  
Condensation Product ◽  
Aromatic Aldehydes ◽  
Trifluoromethanesulfonic Acid ◽  
Crystal Structure Analysis ◽  
Fries Rearrangement

The aromatic hydroxyaldehydes 3a-3g, 5a-5f, 8 , 10 can be prepared by the action of BCl3, BBr3 or trifluoromethanesulfonic acid, on the aryl formates 1a-1f, 4a-e, 7, 9 via Fries rearrangement. BBr3 is more effective than BCl3. The activating ability of BBr3 can be improved by addition of FeCl3. Rearrangements which are induced by trifluoromethanesulfonic acid can give rise to the formations of regioisomers, which might be different from the products formed when the reaction is performed with Lewis acids. The yields of the aldehydes are lowered by subsequent condensation reactions. This view was confirmed by the isolation of a condensation product, which was characterized as a dibenzo[a,j]xanthene derivative 6 by crystal structure analysis. For the Fries rearrangement of formyl groups a new mechanism is proposed. 2-Hydroxy-1-naphthaldehyde 5c can be obtained in good yield from formic acid, BBr3, and 2 -naphthol.

scholarly journals Synthesis of tetrasubstituted pyrazoles containing pyridinyl substituents

2017 ◽  
Vol 13 ◽  
pp. 895-902 ◽  
Author(s):  
Josef Jansa ◽  
Ramona Schmidt ◽  
Ashenafi Damtew Mamuye ◽  
Laura Castoldi ◽  
Alexander Roller ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Structure Analysis ◽  
Condensation Product ◽  
Cross Coupling ◽  
Crystal Structure Analysis ◽  
Coupling Reactions ◽  
Reaction Products ◽  
Pd Catalysts ◽  
Cross Coupling Reactions ◽  
Unexpected Reaction

A synthesis of tetrasubstituted pyrazoles containing two, three or four pyridinyl substituents is described. Hence, the reaction of 1,3-dipyridinyl-1,3-propanediones with 2-hydrazinopyridine or phenylhydrazine, respectively, affords the corresponding 1,3,5-trisubstituted pyrazoles. Iodination at the 4-position of the pyrazole nucleus by treatment with I2/HIO3 gives the appropriate 4-iodopyrazoles which served as starting materials for different cross-coupling reactions. Finally, Negishi cross-coupling employing organozinc halides and Pd catalysts turned out to be the method of choice to obtain the desired tetrasubstituted pyrazoles. The formation of different unexpected reaction products is described. Detailed NMR spectroscopic investigations (1H, 13C, 15N) were undertaken with all products prepared. Moreover, the structure of a condensation product was confirmed by crystal structure analysis.

(3-Iminio-1-propenyl)oxy-borates: New Acyclic Betaines from Enaminocarbonyl Compounds and Boron Trifluoride or Triphenylboron – Synthesis, Crystal Structure Analysis, and Quantum Chemical Calculations

2003 ◽  
Vol 58 (2-3) ◽  
pp. 217-225 ◽  
Author(s):  
Joachim Nikolai ◽  
Gerhard Taubmann ◽  
Gerhard Maas
Keyword(s):  
Crystal Structure ◽  
Gas Phase ◽  
Structure Analysis ◽  
Lewis Acids ◽  
Boron Trifluoride ◽  
Natural Bond Orbital ◽  
Nbo Analysis ◽  
Crystal Structure Analysis ◽  
Dft Methods ◽  
X Ray

Adducts of various acyclic enaminoketones and enaminoaldehydes with the Lewis acids boron trifluoride and triphenylboron were prepared. The adducts were characterized by NMR (1H, 13C, 11B) and IR spectroscopy, FAB-MS, and X-ray crystal structure analysis of the adducts of (E)-3- diethylamino-3-phenyl-2-propenal with BF3 (4a) and BPh3 (5a), respectively. The adduct formation occurs at the oxygen atom of the enaminocarbonyl compound and gives rise to a betainic structure with expressed equalization of the bond orders in the enaminocarbonyl moiety. The gas-phase structures of complexes 4a and 5a and of the corresponding free enaminoaldehyde were determined computationally by RHF and DFT methods, and a Natural Bond Orbital (NBO) analysis was undertaken.

Crystal structure analysis of 4-R-phenyl-2,6-dimethyl-3,5-N-(dimethylcarbamoyl)-1,4-dihydropyridines [R=2-nitro (1), 4-methoxy (2) and 3,4-dichloro (3)]

1998 ◽  
Vol 213 (3) ◽  
Author(s):  
M. Bidya Sagar ◽  
K. Ravikumar ◽  
Y. S. Sadanandam
Keyword(s):  
Crystal Structure ◽  
Calcium Channel ◽  
Structure Analysis ◽  
Crystal Structure Analysis ◽  
Calcium Channel Antagonists

AbstractThe crystallographic characterization of the following three calcium channel antagonists is reported here: 2,6-dimethyl-3,5-dicarbamoyl-4-[2-nitro]-1,4-dihydropyridine (

scholarly journals Combined Use of Structure Analysis, Studies of Molecular Association in Solution, and Molecular Modelling to Understand the Different Propensities of Dihydroxybenzoic Acids to Form Solid Phases

Pharmaceutics ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 734
Author(s):  
Aija Trimdale ◽  
Anatoly Mishnev ◽  
Agris Bērziņš
Keyword(s):  
Crystal Structure ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Structure Analysis ◽  
Crystal Structure Analysis ◽  
Molecular Association ◽  
Hydroxyl Groups ◽  
Solid Phases ◽  
Solvent Molecules ◽  
Dynamics Simulations

The arrangement of hydroxyl groups in the benzene ring has a significant effect on the propensity of dihydroxybenzoic acids (diOHBAs) to form different solid phases when crystallized from solution. All six diOHBAs were categorized into distinctive groups according to the solid phases obtained when crystallized from selected solvents. A combined study using crystal structure and molecule electrostatic potential surface analysis, as well as an exploration of molecular association in solution using spectroscopic methods and molecular dynamics simulations were used to determine the possible mechanism of how the location of the phenolic hydroxyl groups affect the diversity of solid phases formed by the diOHBAs. The crystal structure analysis showed that classical carboxylic acid homodimers and ring-like hydrogen bond motifs consisting of six diOHBA molecules are prominently present in almost all analyzed crystal structures. Both experimental spectroscopic investigations and molecular dynamics simulations indicated that the extent of intramolecular bonding between carboxyl and hydroxyl groups in solution has the most significant impact on the solid phases formed by the diOHBAs. Additionally, the extent of hydrogen bonding with solvent molecules and the mean lifetime of solute–solvent associates formed by diOHBAs and 2-propanol were also investigated.

scholarly journals Preparative-scale HPLC Resolution of Metallacyclic η3-Allyltricarbonyliron Complexes and Determination of the Absolute Configuration by X-Ray Crystal Structure Analysis

1999 ◽  
Vol 23 (9) ◽  
pp. 578-579
Author(s):  
Rainer Schobert ◽  
Hermann Pfab ◽  
Jutta Böhmer ◽  
Frank Hampel ◽  
Andreas Werner
Keyword(s):  
Crystal Structure ◽  
Silica Gel ◽  
Structure Analysis ◽  
Absolute Configuration ◽  
Crystal Structure Analysis ◽  
Preparative Scale ◽  
X Ray ◽  
The Absolute

Racemates of (η3-allyl)tricarbonyliron lactone complex Fe(CO)3{η1:η3-C(O)XCH2CHCMeCH2} 1a (X = O) and (η3-allyl)tricarbonyliron lactam complex 2a (X = NMe) are resolved on a preparative scale by HPLC on cellulose tris(3,5-dimethylphenyl)carbamate/silica gel RP-8 and the absolute configuration of (-)-2a is determined by X-ray crystal structure analysis.

Second-Generation Inhibitors for the Metalloprotease Neprilysin Based on Bicyclic Heteroaromatic Scaffolds: Synthesis, Biological Activity, and X-Ray Crystal-Structure Analysis

2005 ◽  
Vol 88 (4) ◽  
pp. 731-750 ◽  
Author(s):  
Stefan Sahli ◽  
Brian Frank ◽  
W. Bernd Schweizer ◽  
François Diederich ◽  
Denise Blum-Kaelin ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Biological Activity ◽  
Structure Analysis ◽  
Second Generation ◽  
Crystal Structure Analysis ◽  
X Ray
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