4-Methyl-2- 2-nitro-5- -phthalazinone

When large groups, such as phenyl, bromo, ethoxycarbonyl or nitro are attached at position 3, the principal products are l-alkylcinnolin-4(l/f)-ones. Cyanoethylation and acetylation of cinnolin-4(l/f)-one takes place exclusively at N-1. Phthalazin-l(2/f)-ones give 2-substituted derivatives on alkylation and acylation. Alkylation of 4-hydroxyphthala2in-l(2/f)-one with an equimolar amount of primary halide in the presence of a base leads to 2-alkyl-4-hydroxyphthalazin-l(2/f)-one and further alkylation results in the formation of 4-alkoxy-2-alkylphthalazinone. Methylation of 4-hydroxy-2-methyl-phthalazinone with dimethyl sulfate in aqueous alkali gives a mixture of 4-methoxy-2-methylphthalazin-l(2/f)-one and 2,3-dimethylphthalazine-l,4(2//,3//)-dione, whereas methylation of 4-methoxyphthalazin-l(2/f)-one under similar conditions affords only 4-methoxy-2-methylphthalazinone. 

Nitration of 4-hydroxymethyl-l(2//)-phthalazinone and its derivative EG-626 with acetyl nitrate has been shown to give, after formation of the methyl nitrate esters, the N-2-nitro derivatives (Scheme 54). An earlier suggestion that the second nitration of EG-626 occurred on the phthal-azinone oxygen was disproved by a combination of spectroscopic methods and an x-ray structure determination <92CPB3327>. 

Methyl-2-[2-nitro-5-(pyrrolidin-l-yl)phenyl]-l(2//)-phthalazinone (14, R = NO2) underwent a one-pot reduction to the corresponding amino analog (14, R = NH2) and dehydrative cyclization to give 5-methyl-9-(pyrrolidin-l-yl)benzimidazo[2,l-fl]phthalazine (15) (substrate, polyphosphoric acid, 100°C Fe powderj, portionwise then 140°C briefly 25%). ... 

Methoxy-2-methyl-5-nitro-1 (2/7)-phthalazinone 4-Methoxy-2-methyl-8-nitro-1 (2/7)-phthalazinone 2-Methoxymethyl- l-oxo-4-pheny 1-1,2-dihydro-6-phthalazinecarbonitrile l-Methoxy-4-methylphthalazine l-Methoxy-4-methylphthalazine 3-oxide... 

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