Rhodium-catalyzed 1,4-additions to enantiopure acceptors: asymmetric synthesis of functionalized pyrrolizidinones.

ABSTRACT

The rhodium-catalyzed 1,4-addition of arylboronic acids to an enantiopure heterocyclic acceptor proceeds under ligand control to effect an asymmetric synthesis of functionalized pyrrolizidinones. The protocol allows convenient access to all four stereoisomers of pyrrolizidinone 3a (Ar = Ph) by appropriate selection of substrate and catalyst.