Diastereoselective Synthesis of β-Lactams by Ligand-Controlled Stereodivergent Intramolecular Tsuji-Trost Allylation

The diastereoselective synthesis of highly substituted beta-lactams by intramolecular Tsuji-Trost allylation is reported. Judicious selection of the ligand on palladium allows selective access to either the trans isomer (in generally good to excellent yield with very high diastereomeric excess) or cis isomer (with yields and diastereoselectivity ranging from modest to excellent depending on the substrate). The reaction proceeds under exceedingly mild conditions (rt, no additives) with a broad range of substrates, which are readily accessible by the Ugi reaction.