Stereoselective synthesis of pyrrolidine derivatives via reduction of substituted pyrroles.

The heterogeneous catalytic hydrogenation of highly substituted pyrrole systems was studied. These aromatic systems could be fully reduced with excellent diastereoselectivity to afford functionalized pyrrolidines with up to four new stereocenters. It is likely that the reaction is a two-step hydrogenation sequence, and that initial reduction of the C=X bond provides a stereocenter that directs the subsequent reduction of the pyrrole.