An efficient synthesis of novel heterocyclic systems incorporating coumarin moiety

Abstract

AbstractPolyfunctional 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.