Carbonylative ring expansion of aziridines to beta-lactams with rhodium-complexed dendrimers on a resin.

Rhodium-complexed dendrimers, supported on a resin, were evaluated as catalysts for the carbonylative ring expansion reactions of a variety of aziridines with carbon monoxide to give beta-lactams. The effects of reaction temperature, solvent, time, and pressure of carbon monoxide on this transformation were also investigated. The dendritic catalysts showed comparable activity to the homogeneous analogue. More importantly, this catalytic system can be easily recovered by simple filtration and recycled without significant loss of activity.