Synthesis of Spiro[indazole-3,3′-indolin]-2′-ones
via [3 + 2] Dipolar Cycloaddition of Arynes with 3‑Diazoindolin-2-ones
and Indazolo[2,3‑c]quinazolin-6(5H)‑ones by Subsequent Thermal Isomerization
An
efficient protocol for facile construction of spiro[indazole-3,3′-indolin]-2′-ones
was developed via [3 + 2] dipolar cycloaddition of arynes with 3-diazoindolin-2-ones
under mild conditions in excellent yields. Subsequent thermal isomerization
of the spiro[indazole-3,3′-indolin]-2′-ones readily
afforded indazolo[2,3-c]quinazolin-6(5H)-ones.