A NEW FACILE SYNTHESIS OF 4-OXO-1,4-DIHYDROCINNOLINES

Ylides I (R, R1 R2 given: H, H, H; H, OCH2O, -; Me, H, H; H, H, Cl), readily available by std. procedures, were converted into cinnolines II by treatment with nitrous acid and subsequent basic hydrolysis of the intermediate 4-oxo-3- (triphenylphosphoranylidene)-3,4-dihydrocinnolines