1- Ethyl-7- -cinnolinone

Ethyl-1 -methoxycarbonylmethyl-2-(o-propylphenylhydrazono)cyclohexane (23) (prepared in situ) gave 4a-ethyl-2-(o-propylphenylhydrazono)-4,4a,5, 6,7,8-hexahydro-3(2f/)-cinnolinone (24) (20% H2SO4, reflux, 30 min 26% after separation from another product) analogs likewise. ... 

Dimethyl-l,3-cyclohexanedione (dimidone, 145) and ethyl 2-(/7-tolylhydra-zono)acetoacetate (146) gave ethyl 4,7,7-trimethyl-5-oxo-l-p-tolyl-l,5,6,7-tetrahydro-3-cinnohnecarboxylate (147) (neat AcONEU, 170°C, 30 min 80%) " the same substrate (145) and benzil monohydrazone (148) gave 7,7-dimethyl-3,4-diphenyl-6,7-dihydro-5(l//)-cinnolinone (149) (or tauto-... 

Note The structure and bonding of 2-methyl-3(2//)-cinnolinone (85), 1-methyl-4(l /)-cinnolinone (86, R = H), l-ethoxycarbonylmethyl-4(l//)-cinnolinone (86, R = COaEt), 2-methylcinnolin-2-ium-4-olate (87, R = H), and 2-ethoxy-carbonyImethylcinnolin-2-ium-4-olate (87, R = COaEt) have been examined by X-ray analysis, nuclear quadrupole resonance, and ab initio calcula-tions " ° ° ° X-ray analyses for l-[2-(hydrazinocarbonyl)ethyl]- (88, R = NHNH2) and l- 2-[(pyrrolidin-l-yl)carbonyl]ethyl -4(l//)-cinnolinone [88, R = N(CH2)s] have been reported. ... 

Acetyl-4(l//)-cinnolinone (59) underwent cyclocondensation with malononi-trile to give 4-methyl-2-oxo-l,2-dihydropyrido[3,2-c]cinnoline-3-carbonitrile (58) (EtOH, trace piperidine, reflux, 2 h 65%) or, with ethyl cyanoacetate, to give 4-methyl-2-oxo-2//-pyrano[3,2-c]ciimoline-3-carbonitrile (60) (neat reactants, 165°C, 5h 70%). The same substrate (59) gave its tMosemi-carbazone (61) (H2NNH2CSNH2, AcOH, reflux, 2 h 70%), which underwent... 

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