111888-39-2Relevant academic research and scientific papers
Synthesis of 3-(2-Chloro-5-nitroanilino and 4-nitroanilino)-1-(2,4,6-trichlorophenyl)-2-pyrazolin-5-ones
Kim, Chang-Kyu,Debellis, Francesco,Maggiulli, Cataldo A.
, p. 325 - 328 (2007/10/02)
A new synthesis of 3-anilino-1-aryl-2-pyrazolin-5-ones in which the pyrazolinone ring is built via N-N bond formation is described. 2-Cyano-2',4',6'-trichloroacetanilide 1 was converted to imino ether hydrochloride 2 which was reacted with anilines in methanol to produce N-arylimino ether 3a,b.Reaction of these N-arylimino ethers with hydroxylamine gave N-arylamidoximes 4a,b.An 1,2,4-oxadiazol-5-one 6a was prepared from the N-arylamidoxime 4a and subjected to base-induced rearrangement.The desired 3-anilinopyrazolinone 7a was obtained only in a very low yield.However, O-acetylation of the N-arylamidoximes 4a,b followed by acid-catalyzed ring closure and rearrangement in the presence of excess acetic anhydride gave a mixture of N-acetylanilinopyrazolinones (e.g. 10) and 4-acetyloxy-3-N-acetylanilinopyrazoles (e.g. 12) which upon acid hydrolysis afforded the 3-anilinopyrazolinones 7a,b in better yield.
