Cleavage of Diethyl Chromonyl α-Aminophosphonate with Nitrogen and Carbon Nucleophiles: A Synthetic Approach and Biological Evaluations of A Series of Novel Azoles, Azines and Azepines Containing α-Aminophosphonate and Phosphonate Groups

A convenient synthetic approach leading to synthesize a series of novel substituted azoles, azines and azepines linked to α-aminophosphonate moiety was achieved. The methodology depends on ring-opening and ring-closure (RORC) of chromone ring of diethyl chromonyl α-aminophosphonate 1 via its reaction with nitrogen nucleophiles such as primary amines, 1,2-, 1,3- and 1,4-bi-nucleophiles in ethanolic sodium ethoxide. Also, treatment of compound 1 with some acyclic and cyclic active methylene compounds under the same reaction conditions afforded interesting novel isolated and fused pyridine systems bearing phosphonate groups at α-position. The screening of antimicrobial activity for the synthesized compounds indicates that connection of pyrazole, oxazepine and benzodiazepine rings with α-aminophosphonate moiety exhibited good antimicrobial effects. Also, evaluation of their antioxidant properties exemplifies that the compounds having 1,5-benzoxazepinyl and 1,5-benzodiazepinyl units in combination with α-aminophosphonic diester moiety are the most powerful antioxidant agents.