Synthesis of New Chromeno[4,3-b]pyrazolo[4,3-e]pyridines Derivatives with Antimicrobial Evaluation

A series of 2-oxo-2,5-dihydro-1H-chromeno[4,3-b]pyridine derivatives were obtained by using a one-pot three component reaction of 2,2-disubstituted chroman-4-one with aromatic aldehydes and 2-cyanoacetamide in the presence of sodium hydroxide under solvent-free conditions. Heating chromenopyridine derivatives with phosphoryl chloride gave the corresponding chloro derivatives. The reaction of the chloro derivatives with hydrazine hydrate afforded dihydrochromeno[4,3-b]pyrazolo[4,3-e]pyridines derivatives. Condensation of the dimethyl derivative compound with the aromatic aldehydes gave 8-Arylideneamino-6,6-dimethyl-10H-chromeno[4,3-b]pyrazolo[4,3-e]pyridine.