Synthesis of a new scaffold: The 7H,8H-pyrimido[1,6-b]pyridazin-6,8-dione nucleus

Abstract

This paper describes a modified method of preparation of a number of α-aryl-α-(pyridazin-3-yl)-acetonitriles via the C-arylation reaction of the corresponding carbanions of phenylacetonitriles using 3-chloropyridazine derivatives. KOH and DMSO were used in the deprotonation process, which made the reaction very simple and safe to perform. Nitriles were obtained in the hydrolysis reaction to the corresponding α-aryl-α-(pyridazin-3-yl)- acetamide derivatives, which were next subjected to cyclization to afford the final products. A number of new derivatives of 7H,8H-pyrimido[1,6-b]pyridazin-6, 8-dione were synthesized in the cyclocondensation reaction of respective α-aryl-α-(pyridazin-3-yl)-acetamides with diethyl carbonate in the presence of EtONa. The structure and composition of the new compounds were confirmed by IR, 1H- and 13C- NMR analyses and by elemental C, H and N analysis. © 2007 by MDPI.