The study of the reaction paths of 4-aryl-4-oxobutanoic acids with terminal aliphatic N,N-diamines

Bicyclic pyrroloimidazolones and pyrrolopyrimidinones were synthesized by reacting aryl-substituted 4-oxobutanoic acids with aliphatic binucleophiles with different alkyl chain lengths using a sealed vessels reactor (SVR). By varying the synthesis conditions, the reaction path was studied and formed intermediates were isolated. The structures of the obtained compounds were proved using a set of FTIR, 1H, 13C NMR spectroscopy methods and X-ray diffraction data. Temperature and pressure changes data collected during the syntheses were analyzed and assigned to the processes which occurred inside the vials. It was shown that the reaction of 4-aryl-4-oxobutanoic acids with terminal aliphatic N,N-diamines starts from the formation of corresponded (AlkN2)2+An2- salts followed by two subsequent dehydration processes giving rise to the corresponding amides and, finally, heterocycles of pyrroloimidazolone and pyrrolopyrimidinone series