Substitution tautomerism

Indazole, 5,5-dimethyl-3-trifluoromethyl-4,5-dihydro-trichomonacidal activity, 5, 291 Indazole, 2-ethoxycarbonyl-reactions, 5, 269 Indazole, 3-fluoro-synthesis, S, 263 Indazole, 1-germyl-synthesis, 5, 236 Indazole, 1-glycosyl-synthesis, 5, 289 Indazole, 2-glycosyl-synthesis, 5, 289 Indazole, halo-reactions, S, 266 Indazole, 2-hydroxy-methylation, 5, 269 Indazole, 3-hydroxy-reactions, S, 264 Indazole, 6-hydroxy-diazo coupling, 5, 86 Indazole, hydroxyphenyl-synthesis, S, 288 Indazole, 3-iodo-synthesis, S, 241 Indazole, l-isopropyl-3-phenyl-reduction, 5, 243 Indazole, 3-mercapto-1 -substituted tautomerism, 5, 265 Indazole, methoxy-... 

Isoxazol-3-ol, 5-methyl- — see Hymexazoi Isoxazoi-5-ones 3,4-disubstituted synthesis, 6, 64 5-substituted tautomerism, 6, 11 synthesis, 6, 64 Isoxazolo[2,3-h][ 1,2]oxazines synthesis, 6, 633 Isoxazolophanes... 

ImidazoI-2-ones betaines, 5, 372 IR spectra, 5, 358 melting point, 5, 367 4-substituted mass spectra, 5, 361 tautomerism, 5, 367 Imidazol-4-ones coupling, 5, 403 Imidazol-4(5)-ones N-substituted tautomerism, 5, 366 lmidazol-5-ones... 

Pyrazolin-5-one, 3-methyl-1 -phenyl-in colour photography, 5, 299 Pyrazolinones 13C NMR, 5, 193 H NMR, 5, 185, 187 colour couplers in colour photography in non-silver photography, 1, 384 IR spectra, 5, 200-202 structure, 5, 170 Pyrazolinones, dichloro-reactions with alkali, 5, 78 Pyrazolin-3-ones 1-substituted tautomerism, 5, 214 Pyrazolin-5-ones reactions... 

Electrophilic attack in imidazole is usually most facile at an annular nitrogen, and there are many examples of Af-aUcylation, -protonation, -acylation, cyanation, -arylation and -silylation. A-Nitration is much less common A-oxidation is virtually non-existent. When an annular nitrogen becomes substituted, tautomerism in the molecules is blocked, and mixtures of isomers are usually formed with substituted benzimidazoles and 4(5)-substituled imidazoles. 

---