Ethyl carbazate

C3H7NO2 51-79-6) see Carisoprodol Felbamate Mebutamate Tybamate ethyl carbazate... 

Dehydrative condensation of pyrrole-2-carboxaldehyde 77 and ethyl carbazate afforded carbethoxyhydrazone 78 in quantitative yield. Cyclization of 78 in the presence of a catalytic amount of sodium hydride (10mol%) in dimethyl-formamide (DMF) at 100°C led to the formation of pyrrolo[l,2-tf][l,2,4]triazin-4-one 27 in 75% yield (Scheme 8) <1999T13703>. 

Ethyl carbazate [4114-31-2] M 104.1, m 44-48", 51-52", b 95.5°/10m, 92-95 /12mm, 100-102°/llmm. Fractionated using a Vigreux column until the distillate crystallises [Allen and Bell Org Synth Coll Vol in 404 1955]. 

The kinetics of the gas-phase elimination of ethyl and /-butyl carbazates have been studied in a static reactor system over the temperature range 220.3-341.7 °C and pressure range 21.1-70.0 torr.13 Theoretical calculations on the thermal decomposition of ethyl carbazate (4) suggest that the reaction proceeds by a concerted non-synchronous mechanism, through a quasi-three-membered ring transition state (Scheme 4). In contrast, the transition state structure for the thermal decomposition of /-butyl carbazate is an almost planar six-membered ring. 

What is in effect a cycloaddition is brought about by combined condensation and substitution reactions when acid hydrazides react with 2-dimethylamino-3-methyl-4-thiobenzodiazepine (90MI1) (Scheme 42). Another method of making a triazolobenzodiazepine, again involving combined substitution and condensation reactions, took place when a 2-thiobenzodiazepine reacted with ethyl carbazate (91JHC365) (Scheme 43). 

The formation of a mixture of unsaturated ketone 156, DBU hydrobromide, and quaternary salt 157 was considered probable in the reaction of bromo ketone 155 and DBU in benzene. When the reaction between 155 and DBU was carried out in tetrahydrofuran in the presence of ethyl carbazate, the hydrazide 158 was isolated in 84% yield (79JOC3793). 

Ethyl a-bromopropionate, 1286 Ethyl /3-bromopropionate, 1118 Ethyl bromopyruvate, 1217 Ethyl t-butyl malonate, 522, 523 Ethyl t-butyl oxalate, 210 Ethyl n-butyrate, 790 Ethyl carbamate, see Urethane S-Ethylcarbamoylcysteine, 383 Ethyl carbazate, see Ethoxycarbonylhydra-zine... 

Reaction of 43 with ethylene oxide followed by chlorination with thionyl chloride gives the chloroethyl-substituted amide 90, which cyclizes with sodium hydride to the benzodiazepine 91, converted by ethyl carbazate (92) to triazolobenzodiazepinones (93).162 When N-substituted anthranilamides are reacted with phosphorus trichloride followed by hydration, benzodiazaphos-phorines (94)163 are obtained (Scheme 16). 

This ring is formed when a triazine-3-thione is heated with ethyl carbazate simultaneously, the amino group is hydrolysed to a carbonyl. r 1z 0... 

Semicarbazide hydrochloride or ethyl carbazate cyclize 2-chloroazines or 2-chloroazepines on heating the compounds in ethanol to form this fused ring in moderate yield. 

Tetrachloro-6-(2,4-dimethylbenzoyl)benzoic acid with ethyl carbazate gave ethyl 5,6,7,8-tetrachloro-4-(2,4-dimethylphenyl)-l-oxo-l,2-dihydro-2-phthalazinecarboxylate (90). ... 

To a 500 ml three-necked, round-bottomed flask equipped with a water-cooled condenser attached to a drying tube containing silica gel, a mechanical stirrer, an addition funnel, and a thermometer was added 46.5 g (0.476 mole) of ethyl carbazate and 200 ml of dry benzene. The solution was stirred and cooled in an ice bath at approximately lO C. A solution of 40 03 g (0.238 mole) of 1,6-hexane diisocyanate, jJ, in 10 ml of benzene was added dropwise over a period of 40 minutes. The temperature was kept at approximately 20-30 C. After 2 minutes, a white solid began to form, and a thick solid was obtained by the end of the addition. The voluminous white slurry was stirred at room temperature for 45 minutes, then was refluxed for 2 hours. The mixture was cooled, and the white solid was filtered using suction filtration, then dried overnight in a vacuum oven at 50 C to yield 88.94 g (99.3%) of white solid m.p. 202-203 C. ... 

A soln. of ethyl carbazate in abs. ethanol added dropwise at 0-10° to a stirred ice-salt-cooled soln. of ethyl iminoacetate hydrochloride in the same solvent, and the product isolated after 4 hrs. stirring below 10° ethyl acetate carbethoxyhydrazone (Y 10%) heated 1 hr. at 150° with excess aniline 3-hydroxy-4-phenyl-5-methyl-l,2,4-triazole (Y 10%). F. e. s. M. Pesson, S. Dupin, and M. Antoine, G. r. 253, 285 (1961). 

The oxidation reactions of hydroxyethylhydrazine, hydrazine, and ethyl carbazate by iodine monobromide (IBr) in acidic media are first order in substrate and oxidant and inverse second order in H+. ... 

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