Synthesis of spiro-3H-indazoles via 1,3-dipolar cycloaddition of arynes with 6-diazocyclohex-2-en-1-one derivatives and fused-2H-indazoles by subsequent rearrangement
Rare spiro-3H-indazoles bearing a carbonyl group adjacent to the spirocyclic quarternary carbon were prepared via 1,3-dipolar cycloaddition reaction of arynes with 6-diazocyclohex-2-en-1-one derivatives under mild conditions.