Preparation of Spiro[indene-1,1′-isoindolin]-3′-ones via Sulfuric Acid-Promoted Cascade Cyclization

The
sulfuric acid-promoted cascade cyclization of 2-(3-hydroxyprop-1-ynyl)­benzonitriles
led to an efficient synthesis of spiro­[indene-1,1′-isoindolin]-3′-ones.
This class of spiro compounds could also be prepared by the sulfuric
acid-catalyzed cyclization of 2-(phenylacryloyl)­benzonitriles, which
were readily derived from 2-(3-hydroxyprop-1-ynyl)­benzamides using
trifluoroacetic acid as a catalyst.