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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 16, Number 11
BKCSDE 16(11)
November 20, 1995 

1,2,4-Triazole Fused Heterocycles; Part 3. Preparation of 1-(1-Phenylethenyl)-5-(N-substituted amino)-1,2,4-triazoles and 4H-1,2,4-Triazolo[/1,5-c][1,3,5]oxadiazines
Kee-Jung Lee*, You-Suk Lee, Dong-Hyuk Song
The reaction of acetophenone 1-ureidoethylidenehydrazones 6 with a mixture of triphenylphosphine, carbon tetrachloride, and triethylamine in dichloromethane provides a general route to 1-(1-phenylethenyl)-5-(N-substituted amino)-1,2,4-triazoles 11 via the electrocyclization of the expected azino carbodiimide intermediates 9 to give the resonance stabilized azomethine imine 10a followed by a proton abstraction from the methyl group by amide anion. However, the same reaction of benzaldehyde 1-ureidoethylidenehydrazones 5 was unsuccessful. Under the same conditions, the reactions of benzaldehyde 1-N-acylureidoethylidenehydrazones 7 or acetophenone 1-N-acylureidoethylidenehydrazones 8 afforded 4H-1,2,4-triazolo[1,5-c][1,3,5]oxadiazines 16 or 17 via the zwitterionic species 15, or a [4+2] intramolecular cycloaddition from the carbodiimide intermediates 14, respectively.
1037 - 1042
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