Furyl(aryl)methanes and their Derivatives. Part 21: Cinnoline Derivatives from 2-Aminophenylbisfurylmethanes

(Z)-4-[4-(5-Methyl-2-furyl)-3-cinnolinyl]-3-buten-2-ones and (Z)-1-[4-(5-ethyl-2-furyl)-3-cinnolinyl]-1-penten-3-ones have been obtained from 2-aminoarylbisfurylmethanes under treatment with isoamyl nitrite/trimethylchlorosilane in dry acetonitrile. Intramolecular cyclisation and furan oxidative ring opening follow the formation of an intermediate diazonium salt. X-Ray analysis proved the cis-configuration of the alkene side chain.