NOVEL SYNTHESIS OF SUBSTITUTED CHLORO-3-(2H)-PYRIDAZINONES FROM PENTANE-2,3,4-TRIONE 3-ARYLHYDRAZONES

Pentane-2,3,4-trione 3-arylhydrazones (1) on treatment with equimolar quantity of NaH, followed by addition of chloroacetyl chloride (2) aff ord the N-chloroacetyl derivatives (3) along with the cyclised product s 5. Compounds 3 on treatment with NaH undergo cyclisation of 5 which are also obtained in good yields by treatment of 1 with 2 in the prese nce of excess NaH. Alternatively, pyridazinones (5) are obtained by tr eatment of 1 with 2 in the presence of either conc. H2SO4 or p-TsOH. T he structures of these compounds have been elucidated on the basis of IR, PMR, C-13 NMR and mass spectral data and elemental analysis.