A facile synthesis of pyrimido[2',3':5',1']pyrazolo [3',4':4,5]pyrimido[1,6-a]benzimidazoles and [1,2,4]triazino[3',4':5',1']pyrazolo[3',4':4,5]-pyrimido[6,1-a]benzimidazoles

摘要

Thieno[2',3':4,5]pyrimido[1,6-a]benzimidazoles 4-7 have been synthesized by the reaction of 3-mercaptopyrimido[1,6-a]benzimidazole with halo ketones and halo esters, respectively. 3-Aminopyrazolo[3',4':5,6]pyrimido[1,6-a]benzimidazole 9 reacted with acetylacetone, ethyl acetoacetate, ethyl benzoylacetate, ethyl #alpha#-chloroacetoacetate and #beta#-aryl-#alpha#-cyanoacrylonitriles to give pyrimido[2",3":5',1']pyrazolo[3'4':4,5]pyrimido[1,6-a]benzimidazoles 13,14a,b 15, 19a-e, respectively. Diazonium salt 20 coupled with each of malononitrile, benzoylacetonitrile, ethyl cyanoacetate, acetylacetone, diethylmalonate and #beta#-keto esters to give [1,2,4]triazino[3",4":5',1']pyrazolo[3'4':4,5]pyrimido[6,1-a]benzimidazoles 21-25a,b, respectively. Structures of the synthesized compounds are confirmed on the basis of elemental analyses, and spectral data.