Aerobic Dehydrogenation of N‐Heterocycles with Grubbs Catalyst: Its Application to Assisted‐Tandem Catalysis to Construct N‐Containing Fused Heteroarenes.

An aerobic dehydrogenation of nitrogen‐containing heterocycles catalyzed by Grubbs catalyst is developed. The reaction is applicable to various nitrogen‐containing heterocycles. The exceptionally high functional group compatibility of this method was confirmed by the oxidation of an unprotected dihydroindolactam V to indolactam V. Furthermore, by taking advantage of the oxygen‐mediated structural change of the Grubbs catalyst, we integrated ring‐closing metathesis and subsequent aerobic dehydrogenation to develop the novel assisted‐tandem catalysis using molecular oxygen as a chemical trigger. The utility of the assisted‐tandem catalysis was demonstrated by the concise synthesis of N‐containing fused heteroarenes including a natural antibiotic, pyocyanine. [ABSTRACT FROM AUTHOR]