1.3.5- Thiadiazines from thioureas

Only one kind of six-membered ring system containing two nitrogens and one sulfur has been prepared from thiourea-type starting materials, namely 1,3,5-thiadiazines. The first report of this sort of preparation is that of Fromm and Weller,65 who in 1908 found that the thiourea... 

The 1,2,4-selenadiazine (53) is formed from allylthiourea and ScaCla. Symmetrical 4-imino-l,3,5-thiadiazines (54) or (55) result from thioureas and sodium dicyanoamide, and 1,3,5-thiadiazinium salts (58) are formed from... 

DiaminO 4,4-dimethyl-l,3,5-thiadiazine hydrobromide was isolated as by-product (418). Benzene sulfonates of cyanohydrin prepared from sodium cyanide and an halobenzoaldehyde, when treated with thiourea or its derivatives, afford 2,4-diamino-5-(p-halogenophenyl)-thiazole benzene sulfonates (447). Similarly, cyanoamido thiocarbamates obtained from cyanamide and isothiocyanates yield substituted 2,4-diaminothiazoles (598). 

Bromo-l-phenylethan-l-one oxime 2 reacts with thiocyanates to give 2-thiocyana-toethan-l-one oximes 3 which, upon treatment with hydrazine hydrate or phenylhydrazine, furnish via the intermediate 4 the 2-hydrazino- or 5-phenyl-2-(phenylhydrazino)-6//-l,3,4-thia-diazines 6a, b.70 Compound 6a is also accessible from phcnacyl bromide and thiocarbohy-drazide.46 2-Bromo-1-phenylethan-1-one oxime reacts with thiourea to afford 5-phenyl-A//-1,3,4-thiadiazin-2-amine 5.70... 

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