Syntheses of spiro[indazole-3,3′-indolin]-2′-ones and spiro[indazole-3,3′-indolin]-2′-imines via 1,3-dipolar cycloadditions of arynes and studies on their isomerization reactions.

A 1,3-dipolar cycloaddition reaction of arynes with 3-diazoindolin-2-ones under mild conditions in excellent yields has been developed, which allows facile access to a library of labile spiro[indazole-3,3′-indolin]-2′-ones. Spiro[indazole-3,3′-indolin]-2′-imines could be obtained as well following the same protocol. The isomerization reaction of spiro[indazole-3,3′-indolin]-2′-ones under thermal or acidic conditions has been efficiently achieved to afford a wide range of indazolo-[2,3- c quinazolin-6(5H)-ones and the one-pot synthesis of indazolo-[2,3- c quinazolin-6(5H)-ones from arynes and 3-diazoindolin-2-ones is also described. Whereas, spiro[indazole-3,3′-indolin]-2′-imines could not undergo the same rearrangement. Image 1 • aSpiro[indazole-3,3'-indolin]-2'-ones and spiro[indazole-3,3'-indolin]-2'-imines could be obtained via 1,3-dipolar cycloaddition reactions of arynes. • c The isomerization reactions of spiro[indazole-3,3'-indolin]-2'-ones under thermal or acidic conditions have been achieved to afford indazolo-[2,3- c quinazolin-6(5H)-ones. • c One-pot synthesis of indazolo-[2,3- c quinazolin-6(5H)-ones from arynes and 3-diazoindolin-2-ones is extensively studied. [ABSTRACT FROM AUTHOR]