No abstract

Series of coumarin and 5,6-benzomcomarin substituted pyrimidine derivatives 11-15 and 22-25 were synthesized, aiming to develop new imaging fluorescent agents. Analogously, treatment of 4-chloropyrimidine analog 16 with coumarin 3-carbohyrazide 5 under MWI condition followed by boiling with NH4OAc in HOAc furnished coumarin-1,2,4-triazolo-pyrimidine analog 18. The fluorescence property was investigated spectrophotometrically in MeOH with Rhodamine 6G as standard dye. All the compounds showed emission in the region between 331 and 495 nm. The quantum yield of all the compounds were found to be weak, except methyl benzocoumarin 3-carboxylate 22 which showed (ΦF = 0.98) in comparison to Rhodamine 6G as standard (ΦF = 0.95).

A new series of 2-amino-6-((4-aryldiazenyl)benzyloxy)-4-chloropyrimidine derivatives 4 - 13 and 2,6-diamino-5-arylazo-4-chloro-pyrimidine analogs 15 - 20 were synthesized from the pyrimidine scaffolds 3 and 14, respectively, via diazotization with various amines. Nucleophilic displacement at the 2,4-diamino-5-arylazo-6-chloro-pyrimidine 16 by different amines afforded the 4-alkylamino analogs 21 - 27. All new compounds were evaluated for their in vitro anti-HIV activity in MT-4 cells as non-nucleoside reverse transcriptase inhibitors on the basis of our previous work. Screening results indicated that 10 and 11 were found to be the only compounds in the series inhibiting HIV-1 replication in cell cultures with EC50 of >1:23 and >2:92 μg mL-1 of a CC50 of 12.30 and 17.52 μg mL-1, resulting in a selectivity index of 10 and 6, respectively. In addition, preliminary structure-activity relationships and molecular modeling of these new analogs are detailed in this manuscript.

A mild and efficient method has been used for the synthesis of ethyl 4-(3-hydroxphenyl)-6-methyl-2-thioxo-1,3-dihydroprimidine-5-carboxylate (monastrol) (2), via Biginelli reaction. Alkylation of 2 with the fluorescent coumarin 3 afforded the new thioether analog 4. Similarly, ethyl 4-(6,8-dichloro-2-oxo-2 H-chromen-3-yl)-6-methyl-2-thioxo-1,2,3,4-tetrahydro-pyrimidine-5-carboxylate (6) was prepared. The synthesized compounds are fluorescent active and show wavelength of maximum absorption (λmax) in UV or visible region in MeOH at room temperature.

A new and simple method for the selective and sensitive determination of trace amounts of nitrite in soil samples is developed by a combination of cloud point extraction (CPE) and spectrophotometry technique. The procedure is based on the Griess reaction on 3,3`-dimethyl benzidine with nitrite in the presence of 1-naphthol in acidic media to form a yellow diazo dye, which shows absorption at lambda max 455nm. The formation of colored diazo dye is followed by extraction into the Triton X-114rich phase. Cloud point extraction method parameters such as surfactant amount, temperature, and incubation time are evaluated and optimized. The results obtained showed a very good linear range of 10-1250 µgL -1 , with good regression coefficients (R 2 ) ≥ 0.9997 and a preconcentration factor of 12.5. The limit of detection (LOD) describes as 3SDblank/m, and the quantification limit (LOQ) describes as 10SDblank/m, where m is the slope of the calibration curve and they are equal to 7.50 and 22.71 µgL -1 respectively. The recommended method can apply to determine the ultra-trace amount of nitrite in soil samples.