Preparation of 2-(3-Methyleneindolin-2-yl)phenols via Sodium Hydride Promoted C–C/C–O Bond Cleavage

A variety of 2-(3-methyleneindolin-2-yl)phenols were prepared in good to excellent yields through a NaH-promoted C-C/C-O bond cleavage of fused indolines under mild and simple conditions. Mechanistic studies showed that NaH serves as a nucleophile, attacking the aldehyde group of indoline, which is followed by tandem C-C/C-O bond cleavage to afford the desired products. A representative 2-(3-methyleneindolin-2-yl)phenol was easily prepared on a gram scale.