[摘要]:Mechanistic insights of the efficient iridium catalyzed asym. hydrogenation of N-iminopyridinium ylides are reported. Using NMR and mass spectrometry, the nature of the pre-catalyst and role of iodine was studied. The effect of solvent as well as an extensive ligand screening is presented. Deuteration expts. also show that C-H(D) insertion pathways occur in competition with the hydrogenation process.