ChemInform Abstract: New Synthetic Approach to Theophylline and 6-Thiotheophylline Nucleosides from Glycosyl Derivatives of 4, 5-Diaminouracil

ChemInform ◽  
2001 ◽  
Vol 32 (1) ◽  
pp. no-no
Author(s):  
Rodrigo Rico-Gomez ◽  
Juan Manuel Lopez-Romero
Keyword(s):  
Synthetic Approach ◽  
Derivatives Of

A Novel Synthetic Approach to Asymmetric Salen, Dihydrosalen, and Tetrahydrosalen Ligands: Structures and O2-Activating Properties of their Nickel(II) and Cobalt(II) Complexes

1994 ◽  
Vol 49 (8) ◽  
pp. 1089-1100 ◽  
Author(s):  
Arnd Böttcher ◽  
Horst Elias ◽  
Brigitte Eisenmann ◽  
Elke Hilms ◽  
Andreas Huber ◽  
...  
Keyword(s):  
Equilibrium Constants ◽  
Spectrophotometric Titration ◽  
Acetone Solution ◽  
Synthetic Approach ◽  
Coordination Core ◽  
Type Complex ◽  
Square Planar ◽  
Synthetic Procedure ◽  
Derivatives Of ◽  
Methyl Phenyl

A synthetic procedure is described for the preparation of the tetradentate N2O2 ligands H2[H4]L1=6-(2-hydroxyphenyl)-2,5-diaza-3,3-dimethyl-1-(2-hydroxy-3-t-butyl-5-methyl- phenyl)heptane, H2[H2]L1 = 6-(2-hydroxyphenyl)-2,5-diaza-3,3-dimethyl-1-(2-hydroxy-3-t-butyl-5-methylphenyl)-1-heptene, and H2L1 = 6-(2-hydroxyphenyl)-2,5-diaza-3,3-dimethyl-1-(2- hydroxy-3-t-butyl-5-methylphenyl)-1,5-heptadiene, which are asymmetric derivatives of the ligands tetrahydrosalen, dihydrosalen, and salen. Complexes Ni[H4]L1, Ni[H2]L1, NiL1, CoL1, Ni[H4]L2 (([H4]L2)2- = anion of H2[H4]L2 = N,N'-bis(2-hydroxy-3-t-butyl-5-methylbenzyl)- trans-(S,S)-1,2-diaminocyclohexane), and NiL2 were prepared, characterized (VIS and IR ab­sorption, magnetic moment) and subjected to spectrophotometric titration with pyridine, to determine the equilibrium constants for adduct formation. Single crystal X-ray structure analy­ses were carried out for Ni[H2]L1 (monoclinic, P21/n; a = 8.926(4), b = 29.324(7), c = 8.411(4) Å; β = 95.3(1)°; Z = 4), CoL1 (monoclinic, C2/c; a = 25.389(2), b = 18.139(2), c = 10.179(1) Å; β = 112.227(6); Z = 8), and Ni[H4]L2·acetone (tetragonal, P41212; a = 13.928(3), c = 33.698(5) Å; Z = 8). In all of the three complexes, the N2O2-metal coordination core is square-planar. The skeleton of the tetradentate ligand is more or less twisted. The planar cobalt(II) complex CoL1 is a low spin d7 system with μexp = 2.02 BM at 298 K, whereas the planar complexes NiL1, Ni[H2]L1 and Ni[H4]L2 are diamagnetic (μexp = 0.28-0.64 BM). The blue solvate Ni[H4]L1- 3EtOH · H2O is paramagnetic (μexp = 3.04 BM), which points to octahedral coordination. In aerated acetone solution, the tetrahydrosalen-type complex Ni[H4]L1 activates dioxygen and one C-N bond is oxidatively dehydrogenated. The VIS spectrum of the dihydrosalen-type complex formed is virtually identical with that of the aldimine complex Ni[H2]L1. In the pres­ence of dioxygen, Co[H4]L1 and Co[H2]L1 are readily oxidized to CoL1 in acetone solution.

scholarly journals Synthesis of new, highly luminescent bis(2,2’-bithiophen-5-yl) substituted 1,3,4-oxadiazole, 1,3,4-thiadiazole and 1,2,4-triazole

2014 ◽  
Vol 10 ◽  
pp. 1596-1602 ◽  
Author(s):  
Anastasia S Kostyuchenko ◽  
Vyacheslav L.Yurpalov ◽  
Aleksandra Kurowska ◽  
Wojciech Domagala ◽  
Adam Pron ◽  
...  
Keyword(s):  
Good Yield ◽  
Ring Closure ◽  
Quantum Yields ◽  
Synthetic Approach ◽  
Structural Elements ◽  
Target Molecule ◽  
Synthetic Strategy ◽  
Donor Acceptor ◽  
Synthetic Routes ◽  
Derivatives Of

A new synthetic approach towards the preparation of functionalised, soluble, donor–acceptor (DA) alkylbithiophene derivatives of oxadiazole, thiadiazole and triazole is reported. Taking advantage of the Fiesselmann reaction, reactive bithiophene synthons having alkyl or alkoxy substituents at designated positions are prepared. Following a synthetic strategy, featuring the bottom-up approach, sequential structural elements are built, starting from a simple thiophene compound, until the target molecule is obtained, all in good yield. Supplementing the well established methods of oxadiazole and thiadiazole synthesis, efficient ring closure reaction affording a 4H-1,2,4-triazole unit is presented. All target ambipolar compounds display strong photoluminescence with measured quantum yields up to 0.59. Modification of the demonstrated synthetic routes may be exploited for the preparation of longer, specifically functionalised oligothiophenes, coupled to other heteroaromatic cores.

scholarly journals A new and facile synthetic approach to substituted 2-thioxoquinazolin-4-ones by the annulation of a pyrimidine derivative

2010 ◽  
Vol 6 ◽  
pp. 1056-1060 ◽  
Author(s):  
Nimalini Devi Moirangthem ◽  
Warjeet Singh Laitonjam
Keyword(s):  
Ethyl Cyanoacetate ◽  
Pyrimidine Derivative ◽  
Synthetic Approach ◽  
Facile Synthesis ◽  
Benzenoid System ◽  
Active Methylene Compounds ◽  
Pyrimidine Moiety ◽  
Derivatives Of ◽  
Active Methylene

A new and facile synthesis of 2-thioxoquinazolin-4-ones by introducing a benzenoid system in the pyrimidine moiety by reacting ethoxymethylene derivatives of 1,3-diarylthiobarbituric acids (DTBA) with active methylene compounds, such as malononitrile and ethyl cyanoacetate, in presence of ZnCl2 has been developed.

Complexes of the Early Transition Metals with o-Mercaptophenol and 1,2-Dihydroxybenzene

1975 ◽  
Vol 53 (4) ◽  
pp. 572-577 ◽  
Author(s):  
Joel L. Martin ◽  
Josef Takats
Keyword(s):  
Charge Transfer ◽  
Transition Metals ◽  
Synthetic Approach ◽  
Coordination Geometry ◽  
Metal Charge ◽  
Visible Spectra ◽  
Derivatives Of ◽  
Metal Charge Transfer ◽  
Early Transition

A novel synthetic approach, based on the reactivity of amido derivatives of the transition metals, M(NR2)x, towards protic reagents, for the synthesis of complexes of Ti, Zr, Hf, Nb, and Ta with o-mercaptophenol and 1,2-dihydroxybenzene is reported. The complexes, isolated as their tetraalkylammonium and tetraphenylarsonium salts, are moderately air stable, well behaved 2:1 (Ti, Zr, Hf) and 1:1 (Nb, Ta) electrolytes. The u. v.–visible spectra of the complexes, which are somewhat reminiscent of the corresponding benzene-1,2-dithiolates, are dominated by ligand-to-metal charge transfer bands. The band positions change in the expected manner, hypsochromic shifts in the order C6H4S22− < C6H4SO2− < C6H4O22− for a given metal and Ti < Zr ∼ Hf, Nb < Ta, Nb < Zr for a given ligand. lt is argued that these spectral resemblances could be a possible indication of variations in coordination geometry of the reported complexes similar to the ones found in compounds of benzene-1,2-dithiol.

New synthetic approach to aminoethoxy derivatives of p-(tert-butyl)calix[4]arene

2011 ◽  
Vol 47 (4) ◽  
pp. 527-529 ◽  
Author(s):  
A. P. Luk’yanenko ◽  
E. A. Alekseeva ◽  
S. S. Basok ◽  
A. V. Mazepa ◽  
A. I. Gren’
Keyword(s):  
Synthetic Approach ◽  
Tert Butyl ◽  
Derivatives Of
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