Acylhydrazones diacylhydrazines

For convenience, the syntheses discussed in this section are divided into groups, depending on the structures of the starting materials, despite the fact that all of them contain C-N-N-C-O fragments. Therefore, 1,2-diacylhydrazines 109 are described as O-C-N-N-C-O components, acylhydrazones 110 as C-C-N-N-C-O components, while, for example, dithioates and similar compounds 111 are treated as S-C-N-N-C-O components. 

Substituted acylhydrazones (95), formally derivatives of 1,2-diacylhydrazines (75), also cyclize to oxadiazoles (76), with loss of HX. Imidol ethers (95a R2 = H), prepared from acylhydrazines R1CONHNH2 and ortho esters HC(OR)3, cyclize on heating to monosub-stituted oxadiazoles (76 R1 = H). This reaction is an important synthesis of monosubstituted... 

Dichloroazines are accessible by chlorination of either 1,2-diacylhydrazines with PCI5, of acylhydrazones with SOCI2/CI2 or of aldazines with CI2. 

Diacylhydrazines from acylhydrazones and from carboxylic acid hydrazides —Cleavage of semicarbazones s. 16, 356... 

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