ChemInform Abstract: Studies on Pyrazines. Part 27. A New Deoxidative Nucleophilic Substitution of Pyrazine N-Oxides; Synthesis of Azidopyrazines with Trimethylsilyl Azide

Azidopyrazines bearing amino, methoxy and/or phenyl groups have been synthesized by reaction of pyrazine N-oxides with trimethylsilyl azide in the presence of diethylcarbamoyl chloride in refluxing acetonitrile. In most cases, the azidation occurs only at the carbon α to the N-oxide function, and 3-substituted pyrazine 1-oxides gave 2-azido-3-substituted pyrazines. Conversely, methyl, chloro and methoxycarbonylpyrazine N-oxides did not undergo azidation. The electronic and steric effects of the substituent on the reactivity are discussed.