7- Bromo-2-phenyl-1 -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. 

Bromo-6-nitro-l,3-dihydro-l-isobenzofuranone (213) gave 7-nitro-2-phenyl-l(2//)-phthalazinone (214) (3M HCl, reflux, briefly then PhNHNHai, 20°C, 1 h 73%) analogs likewise." "... 

Chloromethyl- gave 7-aminomethyl-2-phenyl-l(2H)-phthalazinone [neat NH4OH d.QM), 20°C, <40 h 82%]. l-(4-Bromo-3-methylphenyl)-4-chlorophthalazine (43, R = C1) gave 4-(4-bromo-3-methylphenyl)-l-phthalazinamine (43, R =NH2) (NaNH2, see original for detail note survival of the extranuclear Br substituent). " ... 

Bromo-2-phenyl-l(2//)-phthalazinone (121) with copper(I) cyanide led to a complex that underwent decomposition on treatment with iron(III) chloride to give 4-oxo-3-phenyl-3,4-dihydro-6-phthalazinecarbonitrile (122) (CuCN, Me2NCHO, reflux, 10 h residue from evaporation, FeCls, HCl, 70°C, 20 min 75%). ... 

Hydrazinocarbonylmethyl-4-phenyl-l(2//)-phthalazinone (78) wifli p-bromo-benzaldehyde gave 2-[(p-bromobenzyIidenehydrazinocarbonyl)methyl]-4-phenyl-l(277)-phthalazinone (79) (reactants, trace AcOH, EtOH, reflux, 2h 70%) or with o-hydroxyacetophenone gave 2-[(o-hydroxy-a-methylbenzyli-denehydrazinocarbonyl)methyl] -4-phenyl-1 (277)-phthalazinone (80) (likewise 80%) other aldehydes or ketones produced analogous products. 

---