Ethyl ester, phenylhydrazone

Some weak electrophilic reagents, which are usually inert toward azoles, also react with quaternized azoles. Diazonium salts yield phenylhydrazones (Scheme 48) in a reaction analogous to the Japp-Klingemann transformation of /S-keto esters into phenylhydrazones in the dithiolylium series illustrated the product has bicyclic character. Cyanine dye preparations fall under this heading (see also Section 4.02.1.6.5). Monomethine cyanines are formed by reaction with an iodo quaternary salt, e.g. Scheme 49. Tri- and penta-methinecar-bocyanines (384 n = 1 and 2, respectively) are obtained by the reaction of two molecules of a quaternary salt with one molecule of ethyl orthoformate (384 n = 1) or/S-ethoxyacrolein acetal (384 n =2), respectively. 

Dimethyl peroxide Diethyl peroxide Di-t-butyl-di-peroxyphthalate Difuroyl peroxide Dibenzoyl peroxide Dimeric ethylidene peroxide Dimeric acetone peroxide Dimeric cyclohexanone peroxide Diozonide of phorone Dimethyl ketone peroxide Ethyl hydroperoxide Ethylene ozonide Hydroxymethyl methyl peroxide Hydroxymethyl hydroperoxide 1-Hydroxyethyl ethyl peroxide 1 -Hydroperoxy-1 -acetoxycyclodecan-6-one Isopropyl percarbonate Isopropyl hydroperoxide Methyl ethyl ketone peroxide Methyl hydroperoxide Methyl ethyl peroxide Monoperoxy succinic acid Nonanoyl peroxide (75% hydrocarbon solution) 1-Naphthoyl peroxide Oxalic acid ester of t-butyl hydroperoxide Ozonide of maleic anhydride Phenylhydrazone hydroperoxide Polymeric butadiene peroxide Polymeric isoprene peroxide Polymeric dimethylbutadiene peroxide Polymeric peroxides of methacrylic acid esters and styrene... 

The reaction of aroylhydrazines with DMAD gives rise to the hydrazones of oxaloacetic ester, which undergo thermal transformation to the corresponding diaroylhydrazines. b. Hydrazones. Ethyl l,3,5-triphenylpyrazole-4-carboxylate has been reported to be formed in the reaction of benzaldehyde phenylhydrazone with ethyl phenylpropiolate. In a detailed investigation, George and co-workers have shown that aldehyde phenylhydrazones react with DMAD, yielding a mixture of pyrazoles and pyrazolines. Thus, in the reaction of benzaldehyde phenylhydrazone with DMAD, products such as dimethyl l,3-diphenylpyrazoline-4,5-dicarboxylate (129), dimethyl... 

This general procedure is effective for the preparation of many types of phenylhydrazones. For example, a substituted diazo compound can be employed.2 Alkylated acetoacetic esters 8 and ethyl benzoylacetate 4 may be used. For the higher homologs, the a-formyl derivatives of ketones may be used in place of ethyl acetoacetate.6 6 Ethyl pyridylacetates may also be substituted for ethyl acetoacetate.7 The products in these cases are the phenylhydrazones of 2-acylpyridines. 

Additional evidence was obtained for the structure (110) of the compound derived from D-mannose, ammonia, and ethyl acetoacetate. This substance, when suspended in water and kept at room temperature, is slowly hydrolyzed, giving di-n-mannosylamine, isolated in the crystalline state, and n-mannose, characterized as its phenylhydrazone. Acetylation gives a tetra-O-acetyl derivative (111). The infrared spectrum of this acetate shows bands at 3280 cm. , attributable to the presence of an intramolecularly bonded NH group, and at 1658 cm. S probably due to the carbonyl group of the /3-amino a, 8-unsaturated ester also involved in a hydrogen bond. Mild, acid hydrolysis of (111) gives 2,3,4,6-tetra-O-acetyl-D-mannose. 

In 1887, in an attempt to prepare the azo ester 4 by coupling benzenediazonium chloride 2 with ethyl 2-methylacetoacetate 1, Japp and Klingemann obtained a product which was recognized as the phenylhydrazone of ethyl pyruvate 3.1"4... 

Japp and Klingemann found that benzenediazonium salt 2 coupled with ethyl methylacetoacetate 1 in alkaline solution to give the phenylhydrazone of ethyl pyruvate 3 with elimination of acetic acid. However, if the ketonic ester was first hydrolyzed with alkali and then coupled, the product was monophenylhydrazone 10, with carbon dioxide being eliminated rather than acetic acid.6... 

In this reaction, the phenylhydrazone of ethyl acetoacetate was isolated as an intermediate and converted into the product. Further intermediates were detected by means of C-NMR spectroscopy [137]. Acetylenecarboxylic esters also react with hydrazines to give pyrazolones. 

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