Carboxylic acid hydrazides degradation

Aminopyrazole has been prepared by a Curtius degradation of pyrazole-3(5)-carboxylic acid hydrazide,2 3 by saponification and decarboxylation of ethyl 3-aminopyrazole-4-carboxy-late 4 obtained from ethyl ethoxymethylenecyanoacetate and hydrazine, and by the present procedure.6,6... 

A soln. of cis-3-benzamidopyrrolid-2-one-4-carboxylic acid hydrazide in 3%-HCl cooled and treated with 10%-NaNO2-soln., the resulting azide (Y ca. 100%) treated with dioxane and heated 1 hr. on a water bath cis-l-benzoyl-4-amino-methylimidazolid-2-one-5-carboxylic acid lactam (Y 77.6%).—The trans-isomer undergoes normal Gurtius degradation. J. Sicher et al.. Coll. 24, 3719 (1959). 

Methyl-3,3 -bipyridine has been oxidized by permanganate to 3,3 -bi-pyridine-4-carboxylic acid. " 3,3 -Bipyridine carboxylic acids are easily decarboxylated and have been esterified and converted to amides, hydrazides, and acylazides. The Hofmann degradation, of the diamide of 3,3 -bipyridine-2,2 -dicarboxylic acid affords the expected 2,2 -diamino-3,3 -bipyridine, but some of the tricyclic system 108 is formed as well. A 2,2 -bis(acylazide) is converted to a similar tricyclic system with ethanol via the intermediate isocyanate, and several related reactions have been described. The simultaneous dehydration... 

Concerning carboxylic acids and their derivatives, transformations of practical value are restricted to oxidative hydrolysis such as the conversion of hydrazides back to carboxylic acids, transamidation of iV-acyl-5,6-dihydrophenanthridines, and decarboxylative processes, especially the degradation of a-hydro-xymalonic acids (eq 9). In some cases the Ce oxidation is much superior to periodate cleavage. A related reaction is involved in a route to lactones. ... 

Stepwise Degradation to Amino Adds. There are several approaches to the transformation of a di- or poly-carboxylic acid to an amino acid. The most satisfactory procedure makes use of the ester acids and their salts. They react with hydrazine to form hydrazide acids, which may be degraded through the azide acids to amino acids. From substituted malonic esters a-amino acids are obtained. (For the preparation of a-amino acids from substituted cyanoacetic esters, see p. 359.) Thus, the potassium salt of the monoethyl ester of methylmalonic acid, which is prqjared by half hydroly of the diethyl ester, pves alanine ethyl ester hydrochloride in 67% yield. Many other amino acids have... 

In general, hydrazides may be prepared by many of the methods analogous to those used in the preparation of amides. For example, hydrazine salts of carboxylic acids and reactions of hydrazine with esters, acyl halides, acyl anhydrides, and amides may be used to produce hydrazides. A reaction analogous to the Hofmann degradation is the formation of hydrazides from ureides (acylureas) [54] (Eq. 4). 

Esterification at room temp, with tetrachloroaluminic acid ether complex has been described The alcoholysis of a-mono-alkylacetoacetates to the corresponding esters and alkyl acetates has been accomplished with excellent yields A new modification of the Curtius degradation avoids the prepn. of acid chlorides by using in their place carboxylic alkoxyformic anhydrides intermediates well-known in peptide chemistry. Among recent developments in this latter field are the use of mixed anhydrides prepared with diphenylketene an improved peptide synthesis via azides prepared with nitrosyl chloride or butyl nitrite instead of aq. sodium nitrite and a rapid synthesis directly from acid hydrazides with N-bromosuccinimide Oligopeptides and /5-lactams have been synthesized from simple starting materials and isonitriles,... 

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