SYNTHESES OF ALPHA-HALOFORMYLARYLHYDRAZINES AND THEIR SELF-DIMERIZATIONS

alpha-Haloformylarylhydrazine hydrohalides 1 were prepared through rin g opening of 3-aryl-4-halosydnones 7 with hydrohalic acids in EtOAc in moderate yields. Reactions between compounds 1 and primary alcohols g ave alkyl 1-arylhydrazinecarboxylates 12 and 14, important intermediat es in syntheses of antiinflammatory drugs. Compounds 16, yl-2-(arylhyd razin-1-yl)-1,3,4-oxadiazolin-5-ones, and compounds 18, l-1,4-dihydro- 1,2,4,5-tetrazine-3,6(2H,5H)-diones, were synthesized by self-dimeriza tion of compounds 1. Compounds 18 were also converted to compounds 17 via intramolecular rearrangement. Structural elucidation and verificat ion of the reaction mechanisms are presented.