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1.
Emmanuel A. Adegoke Babajide I. Alo Oluwole B. Familoni 《Journal of heterocyclic chemistry》1987,24(1):107-110
Regiospecific synthesis of 4H-3,3a-dihydrothiazolo[4,3-b]quinazolines and 7-methyl-4H-3,3a-dihydrothiazolo[4,3-b]quinazolines IVa and IVb is described. The N-substituted thiazolidinecarboxylic acids Ia and Ib were converted to the corresponding acid chlorides, IIa and IIb but neither reacted with silver trifluoromethanesulphonate. The carboxylic acids Ic and Id were however, decarboxylated to the corresponding iminium ions using phosphorus oxychloride and these afforded the nitroamines IIIa and IIIb. Reductive cyclisation led to the quinazolines IVa and IVb. 相似文献
2.
1,2,3,3a-Tetrahydro-9-nitropyrrolo[1,2-α]quinoxalin-4-one and 7,8,9,10-tetrahydro-3-nitropyrido[1,2-α]quin-oxalin-6-one (V-VI) were reduced and deaminated to give new parent tricyclic quinoxalinone skeletons I-II. The latter compounds were identical with the tricycles obtained by an unambiguous independent synthesis. New 6-aza-1,2,3,3a-tetrahydropyrrolo[1,2-α]quinoxalin-4-one (III) and 4-aza-7,8,9,10-tetrahydropyrido[1,2-α]-quinoxalin-6-one (IV) were prepared by selective hydrogen transfer reductive cyclisation of esters of N-(2-nitro-3-pyridyl)pyrrolidine-2-carboxylic acid and N-(2-nitro-3-pyridyl)piperidine-2-carboxylic acid (Xb and XIb) respectively. 相似文献
3.
E. A. Adegoke T. A. Emokpae H. Ephraim-Bassey 《Journal of heterocyclic chemistry》1986,23(4):1195-1198
Synthetic routes to 2,2-disubstituted chromanes and their hetero-ring-unsaturated analogues are briefly reviewed. A variety of common alkylating agents has been involved in such routes. Here, however, the alkylating agent is the lithiated form of 4-tetrahydropyran-2-yloxybuta-1-2-diene V. This reacted with benzophenone to give XIV. The synthesis of chromane XIV is here reported for the first time. The route to XIV is also both new and may prove versatile to other hetero-ring-substituted chromanes. 相似文献
4.
E. A. Adegoke Babajide I. Alo F. O. Ogunsulire 《Journal of heterocyclic chemistry》1982,19(5):1169-1172
New tricyclic quinoxalinone skeletons with a fully-reduced ring ‘C’ -1,2,3,3a-tetrahydropyrrolo[1,2-α]quin-oxalin-4-one (I-II) and 7,8,9,10-tetrahydropyrido[1,2-α]quinoxalin-6-one (III-IV) derivatives were obtained by selective hydrogen transfer reductive cyclisation of N-(2-nitrophenyl)pyrrolidine-2-carboxylic acid esters and N-(2-nitrophenyl)piperidine-2-carboxylic acid esters (VIa,b and VIIIa,b), respectively. 相似文献
5.
Four types of water-soluble luminescent quantum dots (QDs) whose surface was functionlaized with thioglycolic acid (TGA), 3-mercaptopropionic acid (MPA), or glutathione (GSH), were investigated for the sensitive and selective detection of hydroxyl radical (●OH) in aqueous media. It was found that the type of capping agent and QD influenced the sensitivity of the probe. The order of sensitivity of the probe was: GSH-CdTe@ZnS > MPA-CdTe@ZnS > TGA-CdTe > MPA-CdTe QDs. Under the optimum conditions, a limit of detection as low as 8.5?×?10-8?M was obtained using GSH-CdTe@ZnS. The effects of foreign reactive oxygen species and the Fenton reactants and products as possible interferences on the proposed probe were negligible for CdTe@ZnS QDs. Besides, experimental results indicated that CdTe@ZnS QDs were more attractive for the selective recognition of ●OH than CdTe QDs. The mechanistic reaction pathway between the QDs and ●OH is proposed. 相似文献
6.
M.A. Noginov G. Zhu M. Bahoura J. Adegoke C. Small B.A. Ritzo V.P. Drachev V.M. Shalaev 《Applied physics. B, Lasers and optics》2007,86(3):455-460
The compensation of loss in metal by gain in interfacing dielectric has been demonstrated in a mixture of aggregated silver
nanoparticles and rhodamine 6G dye. An increase of the quality factor of surface plasmon (SP) resonance was evidenced by the
sixfold enhancement of Rayleigh scattering. The compensation of plasmonic losses with gain enables a host of new applications
for metallic nanostructures, including low- or no-loss negative-index metamaterials.
We have also predicted and experimentally observed a suppression of SP resonance in metallic nanoparticles embedded in dielectric
host with absorption.
PACS 61.46.Df; 73.20.Mf; 78.67.Bf 相似文献
7.
Azo-hydrazone tautomerism is a phenomenon that occurs in azo dyes possessing substituents conjugated to the azo linkage which has labile proton that can be exchanged intramolecularly. Thus the predominance of one tautomer over another is a function of many factors among which are solvent polarity, solvent type, solute-solvent interactions and the structure of the dye molecule itself. The 4-carboxyl-2,6-dinitrophenylazohydroxynaphthalenes, previously shown to exhibit azo-hydrazone tautomerism, were studied for the relative predominance of one form over another based on interaction at the microenvironment of binary solvent mixtures containing DMF and non-hydrogen bonding (CCl(4)), hydrogen bond donor (toluene, chloroform), hydrogen bond acceptor (acetonitrile, acetone) and the alcohols; ethanol and methanol as solvent pairs. The three dyes gave two main bands in the 50:50 mixture of DMF with these solvents consisting of a high energy band at 250-382 nm while the low energy bands for the dyes occurred at 415-485 nm. Spectral shifts in the binary solvent mixtures were related to the solvent dipolarity, basicity of the less polar component relative to DMF, substituent type, molar transition energy, formation constant for the hydrogen-bonding solvated complexes and the standard free energy change for hydrogen bonding with DMF. The relative predominance of the hydrazone tautomer bears a direct relationship to the basicity of the solvent, presence of hydrogen bond donor substituent and was associated with high molar transition energies and low formation constant. The microenvironment surrounding the dye molecules played a major role in the stability of one tautomer relative to the other. 相似文献
8.
A new spectrophotometric method for the assay of hydralazine hydrochloride in bulk and dosage forms has been developed. The procedure is based on a condensation reaction between alcoholic solution of hydralazine and acidic solution of p-dimethylaminobenzaldehyde to generate an instant greenish-yellow coloured product. The hydrazone formed absorbed visible light strongly and optimal detector response was obtained at a wavelength of 470 nm with a molar absorptivity of 3.652 × 103 l mol?1 cm?1. Optimization of temperature and time revealed 30 °C and 10 min as the best conditions for optimal color formation, while methanol was found to be the most suitable alcohol as diluting solvent. The reaction product is stable for at least 24 h. Beer’s law was obeyed in the concentration range of 2–10 μg ml?1. Recovery studies over three days gave a mean recovery of 101.87% with a relative standard deviation of 1.29%. There was no interference from commonly used tablet excipients. There was no significant difference between the results obtained with the new method and the BP iodimetric method (p > 0.05). The proposed method is simple, sensitive, rapid and economical, and could find application as an in-process quality control method for hydralazine. 相似文献
9.
10.
We have investigated the one-dimensional spin-1/2 axial next-nearest-neighbour Ising (ANNNI) model in two orthogonal magnetic
fields at zero temperature. There are four different possible ground state configurations for the ANNNI model in a longitudinal
field, in the thermodynamic limit. The inclusion of a transverse field introduces quantum fluctuations which destroy the existing
spin order along certain critical lines. The effects of the fluctuations in three of the four ordered regions were investigated
using the finite-size scaling technique. The phase boundaries of the ANNNI model in two orthogonal magnetic fields were thus
determined numerically. For certain limits of the Hamiltonian we compared the obtained results with the existing literature
and our results were in good agreement with the results in the existing literature. 相似文献