Synthesis of 2-alkenylquinoline by reductive olefination of quinoline N-oxide under metal-free conditions is disclosed. Practically, the reaction could be performed with quinoline as starting material via a one-pot, two-step process. A possible mechanism is proposed that involves a sequential 1,3-dipolar cycloaddition and acid-assisted ring opening followed by a dehydration process.

Cp*CoIII-catalyzed tandem inert C–H alkenylation/annulation of N-sulfonyl ketimines with alkynes is revealed. A series of spiro indenyl benzosultams were facilely prepared in good yields under mild reaction conditions.