Orthocarboxylic reaction with hydrazide

Reaction of hydrazides with orthocarboxylic acid esters -f-... 

Orthocarboxylates (353) when heated with hydrazines are said to afford dihydro-1,2,4,5-tetrazines (104) (66M1195, 64JMC814, 03JPR(68)464). The first step of the reaction should be the formation of the hydrazidic ester (354). The thermal cyclization of aliphatic hydrazides ... 

Hydrazide-hydrazones 1 are cyclized by treatment with orthocarboxylates, imidates, or ami-dines in methanol to give l,4-dihydro-l,2,4,5-tetrazines 2 (see Houben-Weyl, Vol. E8c, p 622), which are oxidized by manganese(IV) oxide, mercury(II) oxide, 1,4-benzoquinonc, or air to afford 1,2,4,5-tetrazines 4 the yield is always below 10%.156 The predominant products of the reactions of 1 arc 1.2,4-triazol-4-amines 3.157... 

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See also in sourсe #XX -- [ , ]

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