Diazotization Diethyl malonate

Diphenylcinnoline can be prepared from benzil monophenylhydrazone in the presence of about 80% sulfuric acid (49MI21200). Synthetically more important, however, is the cyclization of mesoxalyl chloride phenylhydrazones under Friedel-Crafts conditions (61JCS2828). As outlined in Scheme 67, the starting mesoxalate phenylhydrazones are obtained by coupling diazotized aromatic amines with diethyl malonate. After conversion... 

Dihydrazide 231 was also used in the synthesis of thienothiophenes containing triazole substituents. For example, the reaction with phenyl isothiocyanate in ethanol produces di(A -phenylthiocarbamoyl)carbohydrazide 238, whose treatment with KOH followed by acidification affords compound 239. Diazotization of dihydrazide 231 with 10% sodium nitrite in acetic acid gives diazide 240. The reactions of the latter with compounds containing the active methylene group, viz., ethyl cyanoacetate, malononitrile or diethyl malonate, in the presence of sodium ethoxide, yield the corresponding ditriazole derivatives 241-243. 

Several reactions of the triazepine (7) have been examined. Heating (7) at 80°C in benzene results in isomerization to form quantitatively benzo[c]dnnoline iV-imide (8), which is also obtained directly from the diaminobiphenyl (5) by aprotic diazotization without isolation of the triazepine intermediate (7). The triazepine (7) reacts as a masked diazonium compound with hydrazine, hydriodic acid, hydrobromic acid and copper, or diethyl malonate to give the corresponding products (9)-(12), respectively (Scheme 2). 

Diazotization of diethyl [(2-aminobenzoyl)[alkyl(or aryl)]amino]malonates 6 gives the cyclized products 7, which on treatment with sodium hydroxide in the cold undergo hydrolysis and partial decarboxylation to the acids 8. The latter afford l//-1.2,4-benzotriazepin-5(47/)-ones 9 when heated in xylene.347... 

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