Green Oxidation Process in the Synthesis of LLM-105 with H2O2/Peroxotungstate System and its Theoretical Study.

A new catalytic system was developed and applied to the involved in the synthesis of LLM-105, in which protonated peroxotungstate combining chitosan was used as catalyst. With H2O2 as oxidant, good to excellent yields could be achieved in the synthesis of pyrazine-1-oxide, 2,6-dimethoxypyrazine-1-oxide, 2,6-dichloropyrazine-1-oxide, and 2-chloro-6-methoxypyrazine-1-oxide without any addition of trifluoracetic acid, which provided a significant exploration toward novel and environmentally benign synthetic route for LLM-105. Theoretical studies were also carried out with Gaussian 03 to evaluate the oxidation process. All of the calculated data matched well with our experimental results. [ABSTRACT FROM AUTHOR]