An efficient synthesis of novel heterocyclic systems incorporating coumarin moiety

Abstract

Polyfunctional 3-chloro-3-(4-chlorocoumarin-3-yl)prop-2-enal (1) used as a precursor for heterocyclic synthesis. Dichloro-aldehyde 1 was allowed to react with variable nucleophilic reagents, and a diversity of heterocyclic systems linked coumarin moiety at position 3 was synthesized. The reaction of compound 1 with guanidine and cyanoguanidine produced 3-(pyrimidin-4-yl)-4-chlorocoumarins 2 and 3. Treating compound 1 with 3-amino-1,2,4-triazole and 2-aminobenzimidazole yielded triazolo[4,3-a]pyrimidine 4 and pyrimido[1,2-a]benzimidazole 5. The treatment of compound 1 with cyanoacetamide, N-benzyl-2-cyanoacetamide, and 1H-benzimidazolylacetonitrile gave 2(1H)-pyridones 6, 7 and pyrido[1,2-a]benzimidazole 8. The reaction of compound 1 with 5-amino-3-methyl-1H-pyrazole and 6-aminouracil afforded pyrazolo[3,4-b]pyridine 9 and pyrido[2,3-d]pyrimidine 10, respectively. Compound 1 reacted with ethylenediamine, o-phenylenediamine, o-aminophenol, and o-aminothiophenol leading to 5-(imidazolylmethyl)chromeno[4,3-e] [1,4]diazepine (12), 3-(benzodiazepin/benzoxazepin-2-yl)-4-chlorocoumarins 13, 14, and 6-(benzothiazol-2-ylmethyl)chromeno[4,3-b][1,5]benzothiazepine 16, respectively. Structures of the new synthesized products were deduced on the basis of their analytical and spectral data.