Of hydrazides

The conversion of esters to hydrazides and of hydrazides to the sulfonyl derivatives occurs in good yield in the McFadyen-Stevens synthesis, but the decomposition of sulfonyl derivatives gives low yields of the desired products, for example, thiazole hydrazide (28) with 10% excess of PhSOjCl in pyridine gave a 75% yield of l-phenylsulfonyl-2-(4-methyl-5-thiazo ecarbonyl)hydrazine (29) (66). The Newman-Caflish modification of the McFadyen-Stevens synthesis gave 37% 4-methyl-5-thiazole-carboxaldehyde (30) (Scheme 27). 

Sulfonic acid hydrazides, RSO2NHNH2, are prepared by the reaction of hydraziae and sulfonyl haUdes, generally the chloride RSO2CI. Some of these have commercial appHcations as blowiag agents. As is typical of hydrazides generally, these compounds react with nitrous acid to form azides (26), which decompose thermally to the very reactive, electron-deficient nitrenes (27). The chemistry of sulfonic acid hydrazides and their azides has been reviewed (87). 

Special reactions of hydrazides and azides are illustrated by the conversion of the hydrazide (205) into the azide (206) by nitrous acid (60JOC1950) and thence into the urethane (207) by ethanol (64FES(19)105Q) the conversion of the same azide (206) into the N-alkylamide (208) by ethylamine the formation of the hydrazone (209) from acetaldehyde and the hydrazide (205) and the IV-acylation of the hydrazide (205) to give, for example, the formylhydrazide (210) (65FES(20)259). It is evident that there is an isocyanate intermediate between (206) and (207) such compounds have been isolated sometimes, e.g. (211). Several of the above reactions are involved in some Curtius degradations. 

A number of hydrazides have been prepared in comparable yields from their respective sulfonyl chlorides by the procedure above. These include -bromobenzenesulfonylhydrazide, p-chlorobenzenesulfonylhydrazide, p - methoxybenzenesulfonylhy-drazide, w-nitrobenzenesulfonylhydrazide, />-nitrobenzenesulfon-ylhydrazide, o-nitrobenzenesulfonylhydrazide, benzenesulfonyl-hydrazide, and methanesulfonylhydrazide. 

The cyclization of hydrazides of aromatic and heteroaromatic acids is likely to give four most probable products diazepines, diazines, 5-iV-aminolactams, and y -iV-aminolactams. 

Another pathway takes place upon cyclization of hydrazides of benzene carboxylic acids in the presence of CuCl in an inert atmosphere in DMF. However, only the cyclization of hydrazide 76 (R = H) in conditions of copper catalysis makes it possible to isolate compound 77 (yield 20%). Other hydrazides of acetylenylbenzoic acids react to give a complex mixture of products (Scheme 132) (85IZV1367 85MI2). 

The cycloisomerization of hydrazide 80, catalyzed by CuCl, gives diazine 81, 5-Ai-aminolactam 82, and, unexpectedly, 6,7-dihydro-4-vinyl-1-methylpyrazolo [3,4-if]pyridazine-7 83 (85MI2) (Scheme 135). 

The data thus obtained allow us to make some generalizations for the heterocy-clization of hydrazides of the vicinal acetylenic derivatives of pyrazolecarboxylic... 

Imidazo[l,5-t/)[l, 2,4]triazin-l(2//)-ones 504 were prepared (78-USP4115572 79JHC277 88USP4743586) by the cyclization of hydrazide 503 with triethyl orthoesters. l,2,3,4-Tetrahydro-2,4,4-trimethyl-8-nitroimidazo[ 1,5-t/J[ 1,2,4]triazin-1 -one 506 was isolated as a byproduct during the course of purification of hydrazide 505, whose structure was determined (91MI4) by crystal structure analysis. They had antiasthmatic... 

Cyclization of hydrazide 954, with triethyl orthoformate gave a mixture of triazolo[4,3-[Pg.144]

The protocol is effective in preparation of hydrazides of 5 carbons or less. Cyclopropanecarboxylic acid hydrazide15 and isobutyric acid hydrazide16 were prepared from their corresponding acid chlorides in 64% and 71% yields, respectively. However, when this method was applied to cyclohexanecarboxylic acid chloride, the bis-acylhydrazide was the predominant product, and the mono-acylhydrazide17 was isolated in 25% yield.18... 

Paul H. Stoye, D. Chap. 10 The Chemistry of Hydrazide, In The Chemistry of Amides, Zabicky J. Ed. John Wiley Sons, 1970 p 515. 

Peng Y, Song G (2001) Simultaneous microwave and ultrasound irradiation A rapid synthesis of hydrazides. Green Chem 3 302-304... 

The creation of hydrazide probes often is based on the derivatization of a detectable molecule with a fezs-hydrazide compound. Although hydrazine itself (in the form of hydrazine hydrate) can be used in a methanolic solution to modify activated carboxylate molecules forming hydrazides, the availability of the bifunctional hydrazides provides a built-in spacer to accommodate greater steric accessibility. 

Wash 100 mg of hydrazide particles 2 times with 10 ml of 10 mM sodium phosphate, 0.15 M NaCl, pH 7.5 (coupling buffer) using centrifugation. 

That a bridged peroxide 68 (for a more detailed discussion, see 1>, p. 84) arises from the intermediate open-chain peroxide formed either by recombination of hydrazide radical ion with. 02( > radical ion, such as 66, or by nucleophilic attack of ion on a carbonyl group of a diazaquinone, such as 67, appears to be very plausible. One of the most important experimental reasons for this assumption has been put forward by E. H. White and M. M. Bursey 106> who, on oxidation of luminol with... 

Scheme 166 shows application of this methodology for preparation of hydrazide 1007. Thus, the reaction of acid 1004 with 1-hydroxybenzotriazole and EDC [l-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride] gives ester 1005 that can be separated and characterized, but it rearranges slowly to isomeric form 1006 in solutions. However, both derivatives, 1005 and 1006, are found to be equally reactive toward hydrazine and afford hydrazide 1007 in 98% isolated yield <2002JOC9471>. 

As in Section 5.06.9.1, the assignments are sometimes arbitrary. Important routes to oxadiazoles, aminooxadiazoles, oxadiazolinones, and oxadiazolinethiones involving the reaction of hydrazides RCONHNH2 with carboxylic acids, acyl chlorides, alkyl esters, or trialkyl orthoesters are described in Section 5.06.9.2.1, reactions with carbon disulfide... 

The reactions of hydrazides with the respective carboxylic acids afforded oxadiazole derivatives 123 <1996JME2753>, 124 <2000BML1645>, 125 <2003JFC163>, and 126 <2004EJM535>. The reactions... 

The well-known reaction of hydrazides with cyanogen bromide, usually performed in the presence of potassium or sodium bicarbonate, affords 2-amino-5-substituted-l,3,4-oxadiazoles. In the past 10 years, this reaction has been applied several times, mainly in order to obtain biologically active derivatives. 

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