Quinol-2- and -4-thiones

In 1939, the ultraviolet spectrum of 4-methylquinol-2-thione was reported to differ from that of the 2-alkylthio analog, and the former compound was concluded to exist in the thione form. However, other investigators were unable to reach any conclusions from ultraviolet and infrared spectral data concerning the tautomerism of quinol-2- and -4-thione. A definitive pK and ultraviolet spectral investigation by Albert and Barlin has recently established that the thione forms of quinol-2- and -4-thione and of isoquinol-1- and -3-thione (cf. 202) greatly predominate (Table V). The infrared... 

Quinoline 1-oxide, hydroxy-, 360 4ff-Quinolizine, 146, 146-150, 153 9aff-Quinolizines, 143-146, 153 Quinol-2- and -4-ones, 348-352 Quinolonediols, 363 Quinol-2- and -4-thiones, 397, 398 Quinoxaline alkyl-, 428 amino-, 415 hydroxy- 378, 379, 384 reaction with dimethyl acetylenedi-carboxylate, 163-164 Quinoxaline-2-thione, 400, 402... 

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... 

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