ChemInform Abstract: Reaction of Ethyl Chloroglyoxylate Arylhydrazone with Heterocyclic Amidine and Difunction Amino Derivatives.

Synthesis and tautomerism of aryl- and hetaryl-azo derivatives of bi- and tri-heterocycles

“…Contrary to the foregoing reports, it was indicated that reaction of 3-phenyl-5-aminopyrazole 2 with each of the hydrazonoyl chlorides 1A, B, C, D yielded the respective 3-substituted-1-aryl-4-phenyl-1H,6H-pyrazolo [3,4-c]pyrazoles 13 instead of the expected arylazo imidazopyrazole 13 0 or its isomeric arylazo pyrrolopyrazole 13 00 (Scheme 5) [20,21]. Such finding needs further evidence to account for such a suggested pathway.…”

“…In contrast to the foregoing results, it was indicated that reactions of 2-aminothiophenol 195 with N-aryl 2-oxopropane hydrazonoyl chloride 1A and ethyl N-(arylhydrazono)chloro- acetate 1B afforded the respective 2-substituted 1,3,4-thiadiazines 197 (Scheme 65) [20,21]. Such reactions need further reinvestigation to confirm such ambiguous results.…”

“…The latter a, 4-CH 3 ; b, 3-CH 3 ; c, H; d, 4-Cl; e, 3-Cl; f, 4-EtOCO; g, 4-CH 3 CO; h, 3-NO 2 ; ithe 3,4-dihydroquinoxalin-2-one derivatives 188 when treated with aqueous sodium hydroxide in ethanol (Scheme 61)[19]. HOMO calculations of the bonding energies of the two possible tautomeric forms indicated that the ketohydrazone structure 188A is more stable than the azo form 188B[83].Treatment of 2-arylhydrazonobenzo-1,4-oxazines 190 with ammonium acetate was reported to give the respective 2-arylazoquinoxaline derivatives 191 (Scheme 62)[84,85].4H-1,4-Benzoxazineso-Aminophenol 189 was reported to react with the hydrazonoyl halides in ethanol in the presence of sodium ethoxide to yield the respective 2-arylhydrazonobenzo-1,4-oxazine 192A or their 2-arylazo-tautomers 192B (Scheme 63)[14,23,43,83,84].In contrast to the foregoing literature reports, it was indicated that reaction of 2-aminophenol 189 with ethyl N-(arylhydrazono) chloroacetate 1B afforded 2-substituted 1,3,4-oxadiazines 193 (Scheme 64)[20]. This reaction requires further confirmation.Reaction of 2-aminophenol 189 with the 2-oxohydrazonoyl bromide 1R was reported to afford the tricyclic compound 194 A, Me; E, XC 6 H 4 ; F, benzofuran-2-yl; P, MeOCO(CH2 …”

“…In contrast to the foregoing established findings, it was reported that reactions of o-phenylenediamine 179 with ethyl N-(arylhydrazono)chloroacetate 1B afforded ethyl 1-aryl-4H-benzo[c][1,2,4]triazine-3-carboxylate 185 via elimination of the aromatic amino group as ammonia from the initially formed amidrazone intermediate 183 (Scheme 60)[20]. This unexpected result needs further investigation.1-Alkylbenzimidazole 186 reacted with hydrazonoyl chlorides 1B and gave the corresponding salts 187.…”

“…Such products were said to exist as a mixture of two tautomeric forms as their 1 H NMR spectra revealed the presence of six protons that exchange with deuterium oxide [81]. as the sole end product and no arylazo-1,4-oxazine was produced (Scheme 64) [20].…”