1H and 13C NMR Study of Bifurcated Intramolecular Hydrogen Bonds in 2,6-Bis(2-pyrrolyl)pyridine and 2,6-Bis(1-vinyl-2-pyrrolyl)pyridine

2005 ◽  
Vol 41 (10) ◽  
pp. 1516-1521 ◽  
Author(s):  
A. V. Afonin ◽  
I. A. Ushakov ◽  
D. E. Simonenko ◽  
E. Yu. Shmidt ◽  
N. V. Zorina ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
13C Nmr ◽  
1H And 13C Nmr ◽  
Intramolecular Hydrogen Bonds ◽  
Nmr Study ◽  
Intramolecular Hydrogen

Synthesis of 4-Aryl-3(5)-(2-hydroxyphenyl)pyrazoles by Reaction of Isoflavones and their 4-Thio Analogues with Hydrazine Derivatives

2007 ◽  
Vol 60 (12) ◽  
pp. 905 ◽  
Author(s):  
Albert Lévai ◽  
Artur M. S. Silva ◽  
José A. S. Cavaleiro ◽  
José Elguero ◽  
Ibon Alkorta ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Nmr Spectroscopy ◽  
Hydrogen Bonds ◽  
Hydrazine Hydrate ◽  
1H Nmr ◽  
Theoretical Calculations ◽  
Intramolecular Hydrogen Bonds ◽  
Nmr Study ◽  
Intramolecular Hydrogen ◽  
New Compounds

4-Aryl-3(5)-2-(hydroxyphenyl)pyrazoles have been prepared by the reaction of isoflavones and their 4-thio analogues with hydrazine hydrate and phenylhydrazine in hot pyridine. The reaction mechanism for the formation of these pyrazoles is discussed. All the new compounds have been fully characterized by NMR spectroscopy. In [D6]DMSO, a 1H NMR study allows observation of the presence of both pyrazole annular tautomers, due to the presence of intramolecular hydrogen bonds in each tautomer (OH···N and NH···O). Theoretical calculations have been carried out on tautomers and conformers of compounds 20 (3(5)-(2-hydroxy-4-methoxyphenyl)-5(3)-methyl-4-phenylpyrazole) and 21 (3(5)-(2-hydroxy-4-methoxyphenyl)-4-(2-methoxyphenyl)-5(3)-methylpyrazole), including the absolute shieldings (GIAO/B3 LYP/6–311++G**) of 21.

scholarly journals Synthesis and Heterocyclization of 4-Hydroxy-3 - ((2-hydroxy-4,4-dimethyl-6-oxocyclohex1-en-1-yl) (aryl) methyl) -2H-chromen-2-ones

2020 ◽  
Vol 20 (4) ◽  
pp. 362-371
Author(s):  
Alexander Yu. Kostritskiy ◽  
◽  
Marina G. Nakonechnikova ◽  
Olga V. Fedotova ◽  
Nina V. Pchelintseva ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
13C Nmr ◽  
Intermediate Complex ◽  
Intramolecular Hydrogen Bonds ◽  
Propionic Anhydride ◽  
Intramolecular Hydrogen ◽  
Aryl Methyl

The possibility of obtaining asymmetric 1,5-diketones based on 4-hydroxy-2H-chromen-2-one and dimedone by three-component condensation in the presence of L-proline as a catalyst is shown. As a result, a series of 4-hydroxy3 - ((2-hydroxy-4,4-dimethyl-6-oxocyclohex1-en-1-yl) (aryl) methyl) -2H-chromen-2-ones was obtained with a yield of 25 up to 73%. The study revealed that the highest yield was observed for compounds containing fragments of ortho-substituted aldehydes capable of forming a hydrogen bond. For meta- and para-substituted – the lowest yield was observed. In the case of ortho-substitution this can be probably explained due to the stabilization of the intermediate complex by two intramolecular hydrogen bonds, which makes it possible to selectively obtain only one final product – 4-hydroxy-3 -((2-hydroxy4,4-dimethyl-6-oxocyclohex-1- en-1-yl) (aryl) methyl) -2Hchromen-2-one. The structure of the obtained products was confirmed by 1 H, 13C NMR, HSQC, HMBC spectroscopy. Considering the 1,5-diketone fragment for the above-described compounds, the possibility of their O-heterocyclization by propionic anhydride was suggested. Boiling 4-hydroxy-3 - ((2-hydroxy-4,4-dimethyl-6-oxocyclohex-1-en-1-yl) (aryl) methyl) -2Hchromen-2-ones in anhydride medium for an hour resulted in obtaining a series of 7- (aryl) -10,10-dimethyl-7,9,10,11-tetrahydro-6H, 8H-chromeno [4,3-b] chromene-6,8-diones. Their structure was also confirmed by 1 H, 13C NMR, HSQC, HMBC spectroscopy.

Controlling emissive properties by intramolecular hydrogen bonds: alkyl and aryl meso‐substituted porphycenes

2021 ◽  
Author(s):  
Jacek Waluk ◽  
Arkadiusz Listkowski ◽  
Natalia Masiera ◽  
Michał Kijak ◽  
Roman Luboradzki ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Intramolecular Hydrogen Bonds ◽  
Intramolecular Hydrogen
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