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Prepare 4-phenylurazole from ethyl carbazate and then oxidize the urazole with gaseous dinitrogen tetroxide to yield 4-phenyl-1,2,4-tri- azoline-3,5-dione la. Modification of the ethyl carbazate procedure in which analytically pure monoalkylhydrazine hydrochlorides were isolated in greater than 90% yield, starting from a ketone or aldehyde. Treatment of primary amines is with chloroamine or hydroxylamine-0-sulfonic acid and the condensation of a carbonyl compound with ethyl carbazate. The FeCl 3 -catalyzed reaction of ethyl carbazate (2 b) proceeded readily to give β-hydroxyester 3 b in better yield. A new one-pot neat synthesis of some 5-aryl-2,4-dihydro-3H-1,2,4-triazol-3-ones through cyclocondensation of ethyl carbazate with aryl nitriles catalyzed by DMAP as an efficient and basic nucleophilic catalyst is described.
A. Davoodnia,; M. Bakavoli,; M. Soleimany,;H. Behm. A new one-pot neat synthesis of 1,2,4-triazol-3-ones through 4-(N,N-dimethylamino) pyridine (DMAP) catalyzed cyclocondensation of ethyl carbazate with aryl nitriles. Chinese Chemical Letters. 2008, 19 (6),685-688.
N. I. Ghali,; D. L. Venton,; S. C. Hung,; G. C. Le Breton. High-yielding synthesis of monoalkylhydrazines. J. Org. Chem., . 1981, 46 (26), 5413-5414.
Forms crystalline ethoxycarbonyl hydrazones with aldehydes and ketones. With o-acylphenols, Pb(OAc)4 treatment of the resulting hydrazone results in replacement of the phenolic OH with ethoxycarbonyl, providing a route to ethyl o-acylbenzoates: Tetrahedron Lett ., 31, 6781 (1990).
Reaction with methyl ketones, followed by treatment with SOCl2, leads to 4-substituted 1,2,3-thiadiazoles: J. Am. Chem. Soc., 77, 5359 (1955). In the presence of base, these readily lose N2 to give alkynethiolates: Can. J. Chem., 46, 1057 (1968):
More recently, this sequence has been used in the synthesis of dendrimers from 1,3,5-triacetylbenzene: J. Chem. Soc., Perkin 1, 2203 (1994).
Dichiarazioni di rischio (UE): H300-H315-H319-H335
Fatal if swallowed. Causes skin irritation. Causes serious eye irritation. May cause respiratory irritation.
Dichiarazioni precauzionali: P280h-P305+P351+P338-P309-P310a
Wear protective gloves/clothing. IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing. IF exposed or if you feel unwell: