Pyrazolo[3,4-b]pyridine in heterocyclic synthesis: synthesis of new pyrazolo[3,4-b]pyridines, imidazo[1',2':1,5]pyrazolo[3,4-b]pyridines, and pyrido[2',3':3,4]pyrazolo[1,5-a]pyrimidines

2007 ◽  
Vol 85 (9) ◽  
pp. 592-599 ◽  
Author(s):  
Mohamed A.M Gad-Elkareem ◽  
Azza M Abdel-Fattah ◽  
Mohamed A.A Elneairy
Keyword(s):  
Pyridine Derivative ◽  
Pyridine Derivatives ◽  
Heterocyclic Synthesis ◽  
Acetyl Acetone ◽  
Active Methylene

Pyrazolo[3,4-b]pyridine derivatives 7 and 9 were synthesized via the reaction of 3-amino-1H-pyrazolo-[3,4-b]pyridine derivative 2 with ω-bromoacetophenones. Reaction of 7 and 9 with Ac2O afforded the imidazo[1',2':1,5]py razolo[3,4-b]pyridine derivative 8 and pyrazolo[3,4-b]pyridine derivative 10, respectively. Reaction of 2 with chloroacetonitrile followed by DMF-DMA gave imidazo[1',2':1,5]pyrazolo[3,4-b]pyridines 4 and 5, respectively. Acetyl acetone and 1,1-dicyano-2,2-dimethylthioethene were reacted with 2 to afford the pyrido[2',3':3,4]pyrazolo-[1,5-a]-pyrimidines 11 and 14, respectively. Also, 2 reacted with DMF-DMA to yield the formamidine 15, which in turn, reacted with active methylene reagents, yielding the corresponding pyrido[2',3':3,4]pyrazolo[1,5-a]pyrimidines 18 and 23a-23d.Key words: 1H-pyrazolo[3,4-b]pyridines, imidazo[1',2':1,5]pyrazolo[3,4-b]pyridines, pyrido[2',3':3,4]pyrazolo[1,5-a]pyrimidines.

scholarly journals Reaction of Malononitrile and Ethyl Cyanoacetate: a Novel Synthesis of Polyfunctional Pyridine Derivatives

1985 ◽  
Vol 40 (11) ◽  
pp. 1537-1540 ◽  
Author(s):  
R. M. Mohareb ◽  
S. M. Fahmy
Keyword(s):  
Carbon Disulphide ◽  
Ethyl Cyanoacetate ◽  
Aromatic Aldehydes ◽  
Pyridine Derivative ◽  
Pyridine Derivatives ◽  
Novel Synthesis ◽  
Active Methylene

Malononitrile reacts with ethyl cyanoacetate to give a polyfunctional substituted pyridine derivative 5. The latter compound reacts with aniline, hydrazines and aromatic aldehydes to give condensated products. The active methylene of 5 couples with benzenediazonium chloride to give the phenylhydrazone derivative which cyclises readily to give a pyrido[2,3-d]pyridazine deriva­tive. 5 reacts with trichloroacetonitrile, and carbon disulphide to give fused heterocyclic deriva­tives.

Nitriles in Heterocyclic Synthesis: A New Synthesis of Some 4H-Naphthopyrans, 2H-Benzothiopyrans and Their Fused Derivatives

1992 ◽  
Vol 57 (7) ◽  
pp. 1570-1574 ◽  
Author(s):  
Abdel-Fattah A. Harb ◽  
Awatef M. El-Maghraby ◽  
Saoud A. Metwally
Keyword(s):  
Heterocyclic Synthesis ◽  
New Synthesis ◽  
Active Methylene

α,β-Unsaturated nitriles are versatile reagents and their chemistry has received considerable attention. The reactivity of cinnamonitriles I toward active methylene reagents has been extensively utilised for synthesis of pyranes.

Multinuclear NMR spectra of [Pt(L)Cl3]− (L = pyridine derivatives) complexes and crystal structure of trans-Pt(2,6-di(hydroxymethyl)pyridine)2Cl2•2H2O

1996 ◽  
Vol 74 (11) ◽  
pp. 2121-2130 ◽  
Author(s):  
Fernande D. , ◽  
Corinne Bensimon ◽  
André L. Beauchamp
Keyword(s):  
Crystal Structure ◽  
Pyridine Ring ◽  
Chemical Shifts ◽  
Bond Distance ◽  
Coupling Constants ◽  
Mirror Plane ◽  
Pyridine Derivative ◽  
Pyridine Derivatives ◽  
Pyridine Ligand ◽  
Twofold Axis

Complexes of the type [Pt(L)Cl3]− (L = pyridine derivative) were synthesized and studied by 13C and 195Pt NMR spectroscopies. The 195Pt signals were observed between −1720 and −1897 ppm. No correlation between the δ(Pt) and the pKa of the protonated pyridine derivatives was found. The chemical shifts vary with the substituents on the pyridine ligand. Compounds with substituents in ortho positions were observed at lower fields, except for complexes containing hydroxy or amine groups. The latter compounds were observed at higher fields, close to the signals of the Pt-unsubstituted pyridine compound. These results were explained in terms of the solvent effect. The chemical shifts δ(C) and the coupling constants J(13C–195Pt) were measured and the results interpreted with a view of obtaining information on the nature of the Pt—N bond. The possibility of π-bonding between platinum and the pyridine ligand is examined. The conformation of the pyridine ring in relation to the platinum plane and the energies of the rotation barriers around the Pt—N bond in these types of platinum(II) complexes are briefly discussed. The crystal structure of trans-Pt(2,6-(HOCH2)2py)2Cl2•2H2O was determined by X-ray diffraction. The compound is monoclinic, C2/m, a = 7.022(6), b = 15.646(13), c = 8.344(10) Å, β = 93.35(8)°, Z = 2, R = 0.037. The platinum atom is located at the junction of the twofold axis and the mirror plane, the N atoms and the para-C atom of the pyridine ring are situated on the twofold axis, and the chloride ligands are on the mirror plane. The compound crystallizes with molecules of water, which are H-bonded to the hydroxy groups. The Pt—Cl bond distance is 2.306(2) Å, and that of the Pt—N bond is 2.041 (6) Å. The dihedral angle between the platinum and the pyridine planes is 79.8°. Key words: platinum, pyridine derivatives, NMR, crystal structure.

Nitriles in Heterocyclic Synthesis: Novel Synthesis of Pyrrole and Pyridine Derivatives

Heterocycles ◽  
1986 ◽  
Vol 24 (12) ◽  
pp. 3341 ◽  
Author(s):  
Sherif Mourad Sherif ◽  
Fathy M. Abdel-Galil ◽  
Mohamed M. Sallam ◽  
Sherif M. Sherif ◽  
Mohamed H. Elnagdi
Keyword(s):  
Pyridine Derivatives ◽  
Heterocyclic Synthesis ◽  
Novel Synthesis
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