The Tetrazole 3-<i>N</i>-Oxide Synthesis

An efficient procedure for transferring an oxygen atom to the 1- or 2-substituted 5-alkyl or aryl tetrazole ring, resulting, for the first time, in the corresponding N-oxides, was developed using HOF·CH3CN. This novel route features mild conditions and high yields. X-ray structure analysis and 15N NMR experiments indicate that the preferred position for the incorporation of the oxygen is on the N-3 atom.