Notes - Triazines. XVI. A New Synthesis for 1,2,4-Triazoles

Abstract

1037nal fraction, b.p. 63-65', probably consisted of an azeotrope. The yield of pure ester represents the minimum value for large mechanical losses were sustained in handling the small sample.We are indebted to the Research Corporation for financial aid in the pursuance of this work. Acknowledgment.MORLEY CHEJIICAL LABORATORY WESTERN RESERVE UNIVERSITY CLEVELAND 6, OHIO Triazines. XVI.

The Chemistry of 1,2,4-Triazoles.

“…The other method involves the reaction of s-triazine with a substituted hydrazine salt (149). For example, from phenylhydrazine hydrochloride 1-phenyl-1,2,4l#-triazole is obtained in 83 per cent yield; similarly, 1-methyl-1,2,4-l#-triazole results in 81 per cent yield from the use of methylhydrazine hydrochloride.…”

Use of the ring opening reactions of 1,3,5-triazines in organic synthesis (review)

“…The reaction with ammonia takes place similarly [20], but the product decomposes on account of its instability in the form of the free base at temperatures above 100°C. If an ammonium salt is used in place of ammonia the yield of formamidine hydrochloride is close to quantitative [7].…”

“…1,2,4-Triazoles are formed as a result [7,55,56] The mechanism of this reaction is also similar to the mechanism presented at the beginning of this Section: The reaction of 2,4,6-triethoxycarbonyl-1,3,5-triazine with arylhydrazines takes place differently with the participation of the ethoxycarbonyl group and leads to the formation of derivatives of 1,2,4-triazine [57] The mechanism is similar to that presented in the previous scheme, but in this case secondary attack by the nucleophile takes place at the ethoxycarbonyl group: Thus, unlike the reactions with 1,4-, 1,5-, and 1,6-binucleophiles, attack in the reactions with 1,2-and 1,3-binucleophiles is realized at two different carbon atoms of the 1,3,5-triazines 1.…”

An overview of the key routes to the best selling 5-membered ring heterocyclic pharmaceuticals

“…It has been proposed that this novel transformation occurs by a two step process: Initially, a molecule of triazine undergoes condensation and ring cleavage with the hydrazine to generate formamidrazone 271 which then immediately reacts with a second molecule of triazine to yield the 1,2,4-triazole [ 81 ]. Hence, in this case the triazine can be considered as a formamide donor.…”