Transferring oxygen isotopes to 1,2,4-benzotriazine 1-oxides forming the corresponding 1,4-dioxides by using the HOF·CH 3 CN complex

Heterocyclic benzotriazine N-oxides are an interesting class of experimental anticancer and antibacterial agents. Analogs with 18O incorporated into the N-oxide group may offer useful mechanistic tools. We describe the use of H218OF·CH3CN in a fast, readily executed and high-yielding preparation of 1,2,4-benzotriazine 1,4-dioxides containing an 18O-label at the 4-oxide position.