Abstract
The N-(4-methyl-2-pyridyl)anthranilic acid (I) was synthesized by Ullmann condensation. The compound (I) was cyclized by polyphosphoric acid (PPA) to give 4-methyl-10H-benzo[b][1,8]naphthyridin-5-one (II). The compound (II) was treated with selenium dioxide (SeO2) and thionyl chloride (SOCl2) to give the 4-formyl-10H-benzo[b][1,8]naphthyridin-5-one (III) and 4-methyl-5-chloro-benzo[b][1,8]naphthyridine (IV) respectively. The compound (III) was reacted with various substituted anilines and aliphatic amines to give the Schiff bases (Va-j). The compound (IV) was reacted with hydrazine hydrate to yield the 5-hydrazino derivative (VI), which was reacted with various aromatic aldehydes to yield the hydrazones (VIIa-j) and the Rf values reported.The reaction progress was followed by thin layer chromatography (TLC). The synthesized compounds were confirmed by spectral data (I.R, 1H-NMR, 13C-MNR). The possible fragmentation pattern of GC/MS for the compounds (III), (Vc) and (VIIg) were reported.
Highlights
The N-(4-methyl-2-pyridyl)anthranilic acid (I) was synthesized by Ullmann condensation
Ullmann synthesis involves the condensation of o-halobenzoic acid with substituted 2-aminopyridine in presence of cupric oxide and anhydrous potassium carbonate to give N-pyridylanthranilic acids (Jameel and Al-Hadedi, 2010)
Cyclization of N-pyridylanthranilic acid can be achived by concentrated H2SO4 (Acheson, 1973), polyphosphoric acid (PPA) (Meftah et al, 1994) and POCl3 (Al-Hadedi, 2008) to give different types of tricyclic hetero compounds
Summary
The N-(4-methyl-2-pyridyl)anthranilic acid (I) was synthesized by Ullmann condensation. This compound was prepared by the procedure reported in the previous work (Al-Hadedi, 2009; Al-Obaydee, 2010). Filtration and evaporation of the solvent to dryness, recrystilazation from ethanol to yield a brown powder, m.p = 103-105 °C, Rf = 0.34 (CHCl3: MeOH, 9.5:0.5), yield 90%.
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