Synthesis of fused tricyclic β-lactams by the Pauson-Khand cyclization of enyne-2-azetidinones

Abstract

Reaction of enyne-β-lactams 1 with Co 2(CO) 8 followed by in situ thermal or TMANO decomposition of the formed alkyne-Co 2(CO) 6 complexes gives tricyclic β-lactams 2 as single stereoisomers, in good to excellent yields. These are the first examples of an intramolecular Pauson-Khand reaction on an enyne system tethered to a four membered ring.