A facile synthesis of highly fluorescent pyrido[2,3-d]pyrimidines and 1,8-naphthyridines via oxazine transformation and enaminic addition reactions

摘要

The synthesis and fluorescence properties of highly substituted bicyclic pryridine derivatives are described. 2-Substituted-4-oxo-pyrido[2,3-d]pyrimidines 2-8 resulted from the acylation reaction of alpha-aminonicotinonitrile 1 with aroyl chlorides, diethyl malonate, morpholine-4-carboxylate, acetic anhydride or formic acid under solvent-free conditions. [4+2] Cyclocondensation and cycloaddition reactions of compound type 1 with formamide and ammonium thiocyanate tolerated the fused pyrimidines 9 and 11, respectively. Finally, the Friedlander-like reaction was applied for the synthesis of 1,8-naphthyridines 12-15 via reaction of compound 1 with cyclohexanone, dimedone, acetyl acetone and benzyl methyl ketone, respectively, under AlCl3 catalysis. The fluorescence spectroscopic data of compounds 1-4, 6-8, 11, 12, 14 and 15 measured and significant results were observed.