Synthesis of Carbapenam Skeletons Using a Ruthenium-Catalyzed Cyclization

Carbapenam is a very important skeleton of β-lactam antibiotics, and it has a highly strained structure. When enynes 9 were treated with RuH2CO(PPh3)3 (10 mol %) in toluene upon heating, carbapenams 10 were obtained in good yields.