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The strategy shown below is adopted in the synthesis is reaction of hydrazine with the 1,4-diketone to give dihydropyridazine. Oxidation of the dihydropyridazine then gives the pyridazine. Carrying out oxidation at this point avoids a cis double bond problem.
Disconnection of pyridazines gives a molecule of hydrazine, and a 1,4-diketone with an alkene in the 2,3-position. A functional group addition , FGA, disconnection gives us the 1,4-diketone.
C. G. Overberger, N. R. Byrd and R. B. Mesrobian, J. Am. Chem. Soc., 1956, 78, 1961–1965.