Enantioselective Hydrogenation of 3-Alkylidenelactams:  High-Throughput Screening Provides a Surprising Solution

High-throughput screening of 256 potential catalysts (8 metal precursors × 32 phosphine ligands) has identified [(BDPP)Ir(COD)]BF4 as a catalyst for the enantioselective hydrogenation of 3-alkylidenelactams. This result is surprising given the highly flexible backbone of the BDPP ligand and the ineffectiveness of this catalyst in other applications. The asymmetric hydrogenation appears fairly general for five- and six-membered lactams and in one case has been scaled up to a 20 kg level.