Formation and structure elucidation of two novel spiro[2 H ‐indol]‐3(1 H )‐ones

The molecular structures of two byproducts 1,1″‐diphenyl‐3′,4′‐dihydrodispiro[indole‐2,2′‐furan‐5′,2″‐indole]‐3,3″(1 H , 1″ H )‐dione (3) and 1,5′‐diphenyl‐4′,5′‐dihydro‐3′ H ‐spiro[indole‐2,2′‐pyrano[3,2‐ b ]indol]‐3(1 H )‐one (4), which accompanied the rearrangement of 3‐hydroxy‐3‐methyl‐1‐phenylquinoline‐2,4(1 H ,3 H )‐dione (1) to 2‐hydroxy‐2‐methyl‐1‐phenyl‐1,2‐dihydro‐3 H ‐indol‐3‐one (2), have been elucidated by NMR, MS, and X‐ray diffraction. Copyright © 2007 John Wiley & Sons, Ltd.