A reinvestigation of the reactions between diazomethane and 1-phenylurazole

Autor: L. H. Wang, Mark J. Bausch
Rok vydání: 1993
Předmět:
Zdroj: Journal of Physical Organic Chemistry. 6:601-608
ISSN: 1099-1395
0894-3230
DOI: 10.1002/poc.610061102
Popis: Exhaustive methylation of 1-phenylurazole (1), using ethereal diazomethane as the methylating agent, results in the formation of three products: 1-phenyl-3,5-dimethoxy-1,2,4-triazole (2), 1-phenyl-3-methoxy-4-methyl-Δ2-1,2,4-triazolinev5-one (3) and 1-phenyl-2,4-dimethylurazole (4). Based on the amounts of 2–4 isolated, the overall yields in these reactions are typically >90%. When 1 and diazomethane were allowed to react in a fashion that resulted in the formation of monomethylated analogues of 1, 1-phenyl-3-methoxy-Δ2-1,2,4-triazoline-5-one (5) and 1-phenylv2-methylurazole (6) were formed. In separate experiments, the monomethylated species 5 and 6 were allowed to react with diazomethane in efforts to develop a sequence of reactions that reasonably accounts for the formation of 2–4. Whereas N- and O-methylated products were obtained when 5 was treated with ethereal diazomethane, the reaction of 6 and diazomethane produced only the N-alkylated product 1-phenyl–2,4-dimethylurazole (in quantitative yield). The outcomes of these experiments are consistent with a sequence of reactions in which the treatment of 1 with diazomethane results, initially, in the formation of the monomethylated species 5 and 6. In the presence of sufficient diazomethane, 5 and 6 then undergo further mothylation, forming the dimethylated species 2–4.
Databáze: OpenAIRE
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