ChemInform Abstract: Synthesis of Arylhydrazonotetrazolopyrimidones, Related Thiazolopyrimidones, Pyrazolopyridones, and Pyrimidobenzimidazoles. Part 4.

Abstract

ChemInform Abstract The 2-arylazo-3-oxobutyrates (I) react with the amino or imino azoles (II), (IV), and (VI) to give the ring closure products (III), (V), and (VII). The hydrazonopentane-2,4-diones (VIII) undergo cyclization with the benzimidazole (IX), producing the phenylazopyrimidobenzimidazole (X).

Synthesis of pyrimido[1,2-a]benzimidazoles from ethyl 2-ethoxymethylidene-3-oxo-3-(polyfluoroalkyl)propionates

“…Up to now, numerous data have been reported on regioselective cyclizations of benzimidazol-2-amine with diethyl malonate and ethyl cyanoacetate [7], 1,3-diketones [7,8], 3-oxo esters and their derivatives [7,9], α,β-unsaturated ketones (chalcones) [4,[10][11][12], and cinnamic acid esters [13]. Initial compounds may also be 1,3-bielectrophiles having an additional electrophilic center.…”