Phthalazinol

Such substrates are usually phthalaldehydes. These give aromatic phthalazines with hydrazine but (partially reduced) phthalazinols with substituted hydrazines, as illustrated in the following examples. 

Phthalaldehyde (39, Q = R = H) gave 2-phenyl-1,2-dihydro-1-phthalazinol (41) (PhNHNH2 HCl, H2O, reflux, 2h 96%) " and thence frtiMj-2,2 -diphenyl-l,l -bi(l,2-dihydrophthalazin-l-ylidene) (42) (AcOH, MeCN, reflux, 2h good yield ) " analogs were made similarly and the structure of trarti-2,2 -di-p-bromophenyl-1,1 -bi( 1,2-dihydrophthalazin-1 -ylidene) was... 

Diphenyl-1,2-dihydro-l-phthalazinol (216) gave 2,4-diphenyl-l(2//)-phtha ... 

Phenyl-1,2-dihydro-1 -phthalazinol (220) gave 2-phenyl-1 (2 /)-phthalazi-nethione (221) (S, MeCN, reflux, prolonged 35% clearly involved more than one step) the same substrate (220) gave 2,2 -diphenyl-l,l, 2,2 -tetrahydro-l,l -biphthalazinylidene (222) (AcOH, MeCN, reflux, 2h 48% after purification from other products) and thence the product (221) (neat substrate, S, 270°C, Nj, 20 min 70%). ... 

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