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.NSFC [21472072, 21302077, 21290183]; Program for Changjiang Scholars and Innovative Research Team in University (PCSIRT) [IRT_15R28]; FRFCU [lzujbky-2016-ct02, lzujbky-2014-188]SCI(E)ARTICLE158228-82338