1.2.4- Triazolo triazine-5-thiones

Two reaction centers of 477-furo[3,2-6]pyrrole-5-carboxyhydrazide (228) (Scheme 15) <84CCC65> were utilized in cyclization reactions with either triethyl orthoformate or orthoacetate, leading to furo[2, 3 4,5]pyrrolo[l,2-d][l,2,4]triazine-8(7H)-one (229). Phosphorus pentasulfide treatment of this product (229) gave the corresponding thione (230) which with hydrazine hydrate gave (231). This compound (231) with triethyl orthoformate gave furo[2, 3 4,5]pyrrolo[l,2- /][l,2,4]triazolo]3,4-/][l,2,4]triazine (232) the 3-methyl (233), 6-methyl (234) and 3,6-dimethyl (235) derivatives were also made. 

Indol-3-yl)-2,3-dihydro-l,2,4-triazine-3-thione was prepared, its X-ray structure determined, and used for the preparation of fused triazolo- and tetrazolotriazines <05RJO875>. Silyl substituted l,2,4-triazin-5-ones have been obtained from a-silyl-a-keto esters and thiosemicarbazide <05TL4049>. 

The synthesis of l,2,4-triazolo[ l,5-J][l,2,4]triazine-5-thiones has been developed in a one pot reaction from 4-amino-l,2,4-triazine-3-thione-5-one and aryl nitriles <05JHC 1021>. 

R-Furo[2, 3 4,5]pyrrolo[l,2-if]-l,2,4-triazine-l-ones (384) by reaction with phosphorus pen-tasulfide gave thiones (385) which, by treatment with hydrazine hydrate, yielded the triazines (386). Reaction of of the latter compounds with triethyl orthoformate or orthoacetate gave 9-R-furo[2, 3 4,5]pyrrolo[l,2-J][l,2,4]triazolo[3,4-/ [l,2,4]triazines (387) and 3- and 6-methyl as well as 3,6-dimethyl derivatives (Scheme 17). 

CftHgN2S3, 2,4-Dimethyl-1,2,4-thiadiazolidine-3,5-dithione, 40B, 338 CftH6Nft03S2, 5-Acetamido-1,3,4-thiadiazole-2-sulphonamide, 40B, 338 Ci,H7N02S, (R)-Thiazolidene-4-carboxylic acid, 45B, 368 C5H5NO3S, 4-Hydroxymethylisothiazole-3-carboxylic acid, 44B, 353 C5H5N3OS, [1,2,4]Triazolo[3,2-b][1,3]thiazin-5-one, 46B, 390 C5H5N3OS2 f 2,3,6,7-Tetrahydro-4H-thiazolo[3,2-a]s-triazin-2-on-4-thione, 40B, 263... 

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