1 -Phenyl-1,2,3-triazole 5-lithiation

Substituted 1,2,4-triazoles have received less attention than their isomeric counterparts, but those results that are available indicate that their lithio derivatives are less stable than their 1-substituted isomers. Thus, in addition to undergoing the expected a-lithiation and reaction at the 5-position, 3-phenyl-4-benzyl-1.2.4-triazole also gave products resulting from ring-opening, even at -78°C (Scheme 65) (86JHC1257). 

C-Lithiations can be easily effected on A -1-protected 1,2,4-triazoles, the resulting 5-lithio derivatives being much more stable than C-hthiated 1,2,3-triazoles 5-Silylation can even be achieved using triethyl-amine with trimethylsilyl bromide - deprotonation of an iV -trimethylsilyl triazolium cation is presumably involved Exactly comparable silylations can be achieved with 2-aryl-l,3,4-oxa- and -thia-diazoles application of this regime to 1-phenyltetrazole produced phenyl trimethylsilyl carbodiimide in 90% yield ... 

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