1,3-Dipolar Cycloaddition Reactions with 1,2,3-Triazinium Ylides
1,3-Dipolar cycloadditions were carried out with 1,2,3-triazinium 2-dicyanomethylylides 4 and deprotonated 2-ethyl-1,2,3-triazinium salts 2. Pyrazolo[2,1-a]- and pyrazolo[1,2-b][1,2,3]triazines 5 and 9 were synthesized, representing new heterocyclic systems. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)