Zur Reaktion von Phenazon und lithiiertem Phenazon mit Aryl-Carbonyl-Derivaten

Some new experimental results are described on the acid catalysed reaction of the 4-Pyrazoline-3-on (1a) with aromatic aldehydes leading to the cationic derivatives4 and5.4-Pyrazoline-3-on-lithium (1b), synthesised for the first time, gives in good yield with 4-dimethylaminobenzaldehyde under mild condition the cyanine2b and with benzophenone the pyrazolyl-diphenylmethane dye8.

Zur Struktur von2a und4a siehe Lit.².