Using 1,2-Diketobenzenes as Substrates

This synthesis affords 1,4-diaIkyl(or aryl)phthalazines, as illustrated in the following examples. 

Appropriately substituted o-benzoylbenzophenones and hydrazine hydrate likewise gave l,4-bis(3,4-dimethoxyphenyl)-6,7-dunethoxyphihalazine (56) (EtOH, reflux, 1 h 80%), l,4-bis-p-chlorophenyl-6,7-dunethoxyphthala- 

Note Such completions of the phthalazine ring have also been used in quite comphcated systems to give, for example, the so-called 4,7,14,17-tetraphenyl [2.2](5,8)phthalazinophane (62) (H2NNH2 HjO, Me2NCHO, 80°C, 10 h 80%) from the appropriate tetrabenzoyl precursor.  

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