Scandium(III) zeolites as new heterogeneous catalysts: [4+2]cyclocondensation of in situ generated aryl imines with alkenes

Abstract

Scandium(III)-exchanged zeolite was used as heterogeneous ligand-free catalysts for the [4+2]cyclocondensation of amines and aldehydes with alkenes through the in situ formation of imines. Such catalysts offered a versatile, efficient, and highly regio- and stereoselective synthesis of tetrahydroquinoline derivatives. These catalysts exhibited a wide scope and compatibility with functional groups. They are very simple to use, easy to remove (by simple filtration), and they are recyclable (up to three times without loss of activity).