Thiohydrazides synthesis

The synthesis of hydrazono derivatives of thiohydrazides is described in reference... 

Activated hydrazine derivatives of carboxylic acids (337, 338) can dimerize to afford dihydro-1,2,4,5-tetrazines (89) which can be oxidized to the tetrazines (39) but which can also rearrange to 4-amino-1,2,4-triazoles (339). In many cases where the isolated products have been formulated as dihydro-1,2,4,5-tetrazines (89) it has either been shown, or it can be assumed, that in fact 4-amino-l,2,4-triazoles (339) were obtained. Very often the formation of dihydro-1,2,4,5-tetrazines (89) is a side-reaction in the synthesis of activated hydrazine derivatives of carboxylic acids, such as amidrazones (337 Y = NH2), hydrazidines (337 Y = NHNH2), thiohydrazides (338 X = S) and so on and not the attempted reaction. Therefore the number of effective synthetic processes for dihydrotetrazines (89) or tetrazines (39) by this synthetic principle is not very high. 

A new cyclising reagent is proposed for the synthesis of 5-unsubstituted 1,3,4-thiadiazoles (133). The latter are formed in good yield by the reaction of thiohydrazides (134) with diethyl chlorophosphate (Scheme 39). A useful, one-pot protocol has been developed for the conversion of enolizable ketones (135) to alkylated or arylated olefins (136) by Pd-catalysed cross coupling of in-situ generated enol phosphates (137) with Grignard reagents (Scheme 40). ... 

Functional group substituents on N-l of 2-pyrazolin-5-ones (Table XXXVII) are acyl, sulfonyl and various carboxyl derivatives, such as carbalkoxy, amides, thioamides, hydrazides, thiohydrazides and amidines. The usual synthesis of these compounds is by the classical 2-pyrazolin-5-one synthesis, reaction of a /J-ketoester with a hydrazine. In these cases the hydrazines are special types such as hydrazide,... 

Of the different thiadiazines, the 1,3,4-thiadiazines have been most extensively studied. They are best prepared by condensation of thiohydrazides with a-halocarbonyl compounds. This ring system was first reported from the reaction of phenacyl bromide with thiosemicarbazide or its 4-substituted derivatives.26 Similar reactions were later investigated,27 29 and important details about the synthesis and reactivity of 1,3,4-thiadiazines were reported in the following years by Beyer etal., Sandstrom, and Bulka et al.7,8... 

A frequently used method for the synthesis of l,4-dihydro-l,2,4,5-tetrazines 17 and, hence, for the preparation of 1,2,4,5-tetrazines 18 is the dimerization of activated hydrazidic acid derivatives, such as hydrazinoyl chlorides 1, thiohydrazides 4, amidrazones 10, selenohydrazides 12, hydrazonic esters 15, hydrazidines 16 or thiohydrazonic esters 13. This corresponds to a synthesis by a (3 + 3) fragment method. 

Among the several papers reporting on the applicability of thioamides " and thiohydrazides in the synthesis of heterocyclic compounds, the most interesting paper is perhaps that of Ofitserov and his co-workers, desc bing the formation of (275) by the action of aqueous ammonia on the meso-ionic thioamide (273) the formation of (275) was explained on the basis of a mechanism involving (274) as a spontaneously rearranging intermediate. ... 

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