Diastereoselective construction of bridged piperidines through an interrupted dearomative reduction.

An interrupted dearomative reduction strategy was developed to transform planar chalcone-based pyridinium salts into structurally intriguing bridged piperidines in a completely regio- and diastereoselective manner. This reaction proceeded successfully by using cheap and easily accessible NaBH 4 as the reductant under mild conditions without exclusion of oxygen or use of special equipment.