Hydrazines acylhydrazines

Acylhydrazines R1 CONF1NF1R2 (R1 = Ph or PhCH2 R2 = Bu, PhCH2 or Ph) are produced by the action of hydroxamic acids R ONHOH on the primary amines R2NH2 in the presence of tosyl chloride or 2-chloro-l-methylpyridinium chloride94. O-(Diphenylphosphinoyl)-A-arylhydroxylamines 77 (R = NO2, Ac, Tos or CN) react with A-methylaniline to afford the hydrazine derivatives 7895. 

N-Acylhydrazine (L) derivatives of the stoichiometry MX2L2 (M = Zn or Cd X = NCS, NO2, NCO or iS04 L = formyl-, benzoyl- or nitrobenzoyl-hydrazine) have been prepared the ligand is N,0-chelate bonded in all cases.154"157... 

A versatile route to 2-aminooxadiazoles (92), which generally proceeds in higher yield than oxidation of thiosemicarbazides (82), is the cyclization in aqueous or alcoholic solution of l-acyl-2-cyanohydrazines (91) prepared from acylhydrazines and cyanogen bromide (Scheme 16). Alternatively, hydrazines (91) are obtained by acylation of cyanohydrazines (66EGP52668). 

The ease of forming C—N and C= N bonds as compared with the difficulty of N—N formation practically prescribes the use of hydrazines in the synthesis of 1,2,4-triazoles. Scheme 59 illustrates synthetic schemes that use one of the following (a) hydrazine, (b) an acylhydrazine, (c) amidrazone or (d) acylamidrazone. The dotted lines leave the presence or absence of a bond open. Thus in (a) possible reactants are (R COX, R COX and NH3) or (R CONHz and R COX) or (R COX and HjNCOR ) or (R CONHCOR ) X stands for a suitable leaving group, usually OH, H2O. 

Pellizzari reaction. Formation of substituted 1,2,4-triazoles by the condensation of amides and acyl hydrazines. When the acyl groups of the amide and acylhydrazine are different, interchange of acyl groups may occur, with formation of a mixture of tri azoles. 

Acylhydrazines to Acyl Azides 453 ArCONHNH2 - ArCON3 Hydrazines to Azides 453 ArNHNH2 - ArN3... 

Acylhydrazines (s. a. Carboxylic acid hydrazides, Sulfonyl-hydrazines)... 

Synthesis from Acylhydrazines. The condensation of acyl hydrazines and ethyl dithioacetate in boiling ethanol furnishes 5-aryl-2-methyl-l,3,4-thiadiazoles, but 1,3,4-oxadiazoles are formed as main products in some cases. Under suitable conditions, the intermediate thioacetylacylhydrazines may be isolated. ... 

The synthesis of a novel class of compounds, the 1,2-diacyl-l-cyano-alky 1-hydrazines, is depicted in Figure 7. The reaction of acid hydrazide with a carbonyl compound such as a ketone or an aldehyde, in the presence of aqueous sodium cyanide and one equivalent of hydrochloric acid, gave the l-cyanoalkyl-2-acyl hydrazine according to a general method described by T. R. Lynch, F. N. MacLachlan, and J. L. Suschitzky (IS). The subsequent acylation for the preparation of the final target molecules can be achieved by adding triethylamine into a mixture of l-cyanoalkyl-2-acylhydrazine and acyl chloride in the presence of 4-dimethylaminopyridine as a catalyst in dry methylene chloride. 

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