1.2.4- Triazolium-3-olates

The reaction of 4-methyl-l,2,4-triazoline-3,5-dione 428 with tetracyclopropylethylene gives 5,5,6,6-tetracyclopropyl-3-methyl-5,6-dihydro-oxazolo[3,2-A][l,2,4]triazolium-2-olate 140 (unreported yield) (Equation 89) <2004JA700>. 

The mesoionic 1,2,3-triazolium-4-olates 361a,b and l,2,3-triazolium-4-thiolate 361c did not react with benzocyclopropene (113), and the attempted reaction between l,3-diazolium-4-olate 362 and benzocyclobutadiene failed (114). In contrast to these negative results, Ichinari et al. (249) found that the isomeric l,3-diazolium-4-olates (l,3-imidazolium-4-olates) 363 and 364 react with DMAD to form pyridones and pyrroles, respectively. 

Mesoionische Verbindungen vom Typ der 1,3-disubstituierten l,2,3-Triazolium-5-olate reagie-ren mit Butindisaure-dimethylester unter 1,3-dipolarer Cycloaddition und anschlieBender Ab-spaltung von Alkyl- bzw. Aryl-isocyanaten zu 1-substituierten 3,4-Dimethoxycarbonyl-1 H-pyrazolen1004,100S ... 

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