polycyclic aromatic hydrocarbon (pah) plays an important role in the formation of combustion-generatedparticles such as soot, and their presence in atmosphere aerosols has been widely shown. the formation of five-membered rings, detected in combustion effluent, is of great interest due to their genotoxic activity.the present study reports an investigation of the electronic structure of acenapht...

This study describes the synthesis and antioxidant activity of new 1,4-disubstituted 1,2,3-triazoles. These compounds were generated semi-synthetically using Cu(I)-catalysed azide-alkyne cycloaddition (CuAAC) reaction between ethyl 2-azidoacetate terminal acetylenes derived from natural products carvacrol, eugenol, isovanillin, thymol vanillin. The obtained at 50 to 80% yield characterised thro...

Quaternisation of 3,5-diaryl-1,2,4-thiadiazoles with trimethylsilylmethyl triflate at 40 8C occurred at N-2. Separate desilylation of the salts resulted in a ring expansion to substituted 2H-1,3,5-thiadiazines 5. Heating of these with ethanolic sodium ethoxide caused sulfur extrusion and ring contraction to 2,4-disubstituted imidazoles 6. 3,4-Diaryl1,2,5-thiadiazoles were less reactive to alkyl...

Divergent syntheses of indolizines and 2,4-disubstituted pyrroles by the silver-catalyzed cyclization of 2-pyridyl alkynyl carbinols with isocyanides are reported. These methods provide an effective route to highly functionalized indolizines and 2,4-disubstituted pyrroles in good to excellent yields. The 2,4-disubstituted pyrroles are synthesized by an unprecedented regioselective [3+2] cycload...

Abstract We report the application of Pd(II)-catalyzed, directing-group-aided C–H arylation/alkylation tactics to functionalize pyrene core, especially, relatively inaccessible C2 and K-region C10 positions core augmentation library derivatives with C1,C2- C1,C10-disubstituted motifs. The Pd(II)-catalyzed β-C–H C2-position pyrene-1-carboxamide possessing an 8-aminoquinoline directing group yiel...

The 2-mono and 2,6-disubstituted methyl-1,4-dihydropyridines were synthesized by reaction of morpholine, thiophenol, 8-hydroxyquinoline, 2-naphthol and 2-mercopto-1-methyl imidazole with the 2-mono bromo and 2,6-dibromo-1,4-dihidropyridines.

A series of different 1-monosubstituted and 1,1-disubstituted 1,2,3,4-tetrahydro-isoquinolines was synthesized in high yields from different ketoamides. We have developed a convenient method for the synthesis of disubstituted derivatives by interaction of ketoamides with organomagnesium compounds, followed by cyclization in the presence of catalytic amounts of p-toluenesulfonic acid (PTSA). A n...

The dominant alkaloids previously identified in skin extracts of Amazonian dendrobatid frogs of the genus Ameerega are histrionicotoxins and 2,5-disubstituted decahydroquinolines. Analysis of alkaloids in skin extracts of Ameerega picta from Bolivia revealed that the alkaloid 257A, previously reported as a 2,5-disubstituted decahydroquinoline, is an N-methyl-2,5-disubstituted decahydroquinoline...

Relative yields of C-6, C-8. and C-6 and C-8 substituted catechins obtained from the reaction of (+ )-catechin or 3' 4',57-tetra-O-methvl-( + )-catechin with pyridinium hydrobromide-perbromide, bromine. p-hydroxybenzyl al~oh~I, or o-hydroxybenZyI alcohol showed differing selectivities depending upon the electrophile used. Ratios of C-6 to C-8 substituted products were 1 : 1.2 for the reaction o...