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

The
diastereoselective synthesis of highly substituted β-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.