Phthalazine 誘導体に関する研究(第6報) : 1-Methylおよび1-BenzylphthalazineのN-Oxidationについて

抄録

N-oxidation of 1-methyl-(I) and 1-benzyl-phthalazine (II) was attempted at lower than 10° in the mixed solvents of chloroform and ether using monoperphthalic acid. 2-Oxide (I₂) and 3-oxide (I₃) were produced from I in a 1 : 2 ratio and from II 2-oxide (II₂) and 3-Oxide (II₃) in almost a 3 : 1 ratio. The position of N-oxide groups were determined by the following procedures. To I₂ and I₃, phenylmagnesium bromide was reacted respectively and the reaction solution was treated with p-benzoquinone to 2-oxide (III₂) and 3-oxide (III₃) of 1-methyl-4-phenylphthalazine (III). III₂ was confirmed by the synthesis separately carried out in reacting 1-phenylphthalazine 3-oxide (IV₃) with methylmagnesium iodide. Therefore, the structure of I₂ was decided and that of I₃ might be suggested. Similar procedures were made in the determination of the structures of II₂ and II₃. It was reported that only 2-oxide (III₂) was produced from 1-methyl-4-phenylphthalazine (III) and that from 1-isopropyl-4-phenylphthalazine (VII), only 3-oxide (VII₃) was produced (Chart 3). N-oxidation of 1-ethyl-4-phenylphthalazine (IX) was attempted and only 2-oxide (IX₂) was obtained (Chart 4).