1.2.4- Triazolo thiazin-5-ones

A variety of N,S-bis(nucleophiles) react with unsaturated 5(47/)-oxazolones to produce triazolo-l,3-thiazin -ones 570 and 1,3-thiazin-4-ones 572. Mechanistically, Michael addition of the bis(nucleophile) to 569 and 571 followed by ring opening with concomitant cyclization leads to the observed products. 

A derivative of a hitherto unknown nucleus was produced when 4-amino-5-aminomethyl-3-methyltriazole was refluxed with carbon disulfide and triethylamine in pyridine, which yielded 3-methyl-3,7-dihydro-l,2,3-triazolo-[4,5-d][l,3]thiazine-5-thione (98) (3 hr, 53%) the 3-benzyl analog was made similarly (63%) [80JCS(P1)2009]. Cyclization of 4-anilino-5-ethoxycarbonyltriazole with polyphosphoric acid produced 1 f/-triazolo-[4,5-h]quinol-4-one (99) [80EUP(A)2562]. Similarly, ring closure of 4-(2-pyridylamino)triazole-5-carboxylic acid (or its esters) gave l//-pyrido-[l,2-a]-l,2,3-triazolo[4,5-d]pyrimidin-4-one (100) (77GEP2757929). 4-Amino-5-formyl-3-methyltriazole and pentane-2,4-dione, set aside in 20% sulfuric acid, yielded 3,5-dimethyl-3//-l,2,3-triazolo [4,5-6] pyridin-6-yl... 

Condensation of anthranilic acid with various ort/zo-esters and reaction of semicarbazides, gave 2-substituted benzoxazin-4-ones and also by the reaction of hydrazones with aryl-/alkyl-ureas and by salicylaldehyde or 2-hydroxyacetophenones with 4-aryl-/alkyl-semicarbazides. Hydrolysis of o-aminoesters and subsequent treatment with phosgene gave 40. Fused oxazine with bridge head nitrogen 41 and triazolo[3,4-Z>]thiazines 42 were also prepared . The 2,3-dihydrobenzoxazine 43, thiomorpholines 44 and phenothiazines 45 were prepared. ... 

A very careful analysis of /hn and Vhc couplings allowed Danilkina et al to determine structures of a series of 2-substituted 5-phenyl-7/f-[l,2,4]triazolo[5,l-Z)][l,3]thiazin-7-ones, which were obtained in a one-step reaction of 1-acylthiosemicarbazides. 

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... 

Ivin et al. obtained 3-(perflnorohexyl)-7-phenyl-5H-[l, 2, 4]triazolo[3,4-b][l,3] thiazin-5-one 76 as a result of a reaction of methyl phenylpropynoate with a linear l-(perfluoroheptanoyl)thiosemicarbazide 77 or a cyclic 5-(perfluorohexyl)triazole-3-thiol 78. In both cases the reaction conditions were practically identical, and the yields of componnds containing the triflnorohexyl group in the position 3 of the 1,2,4-triazole ring were comparable [77]. 

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