Spiro Hydrofuran Oxindole Derivatives by Oxidative Cyclization

Significance

Reported is the one-pot CAN-mediated synthesis of spiro di- and tetrahydrofuran oxindole derivatives by a [3+2] oxidative cyclization of cyclic and acyclic 1,3-dicarbonyl compounds in moderate to good yields. Oxoethylidene derivatives 1 undergo reaction with cyclic and acyclic 1,3-carbonyls to yield single regio- and stereoisomers, the latter incorporating a molecule of water, to yield chemical useful 2-hydroxytetrahydrofuran oxindole derivatives. Similarly, benzylidene derivatives 2 undergo reaction with cyclic 1,3-carbonyls to yield 1:1 mixtures of diastereomers, separable by chromatography. One example of each new spiro hydrofuran oxindole product were characterized by X-ray diffraction analysis.