REACTION OF HYDRAZINOQUINOLINES WITH TRIFLUOROMETHYL-BETA-DIKETONES -STRUCTURAL AND MECHANISTIC STUDIES

Reaction of 2-hydrazino-4-methylquinoline with a series of trifluorome thyl-beta-diketones gives nolin-2-yl)-5-trifluoromethyl-4,5-dihydropyr azoles and, in some cases, 5-substituted-1-(4-methylquinolin-2-yl)depe nding on the substitution of the diketone. Dehydration of the hydroxyd ihydropyrazoles can be effected with sulphuric acid in acetic acid to give the regioisomeric 4-methylquinolin-2-yl)-5-trifluoromethylpyrazol es. In contrast, the reaction of two 4-hydrazinoquinolines with 1,1,1- trifluoropentane-2,4-dione afforded a different isolable intermediate, the corresponding hydrazone formed at the 4-carbonyl. Dehydration gav e the uinolin-4-yl)-3-methyl-5-trifluoromethylpyrazoles. The regioisom eric identity of the pyrazoles was established using F-19 NMR. (C) Els evier Science S.A.