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 <b>9</b> were treated with RuH<sub>2</sub>CO(PPh<sub>3</sub>)<sub>3</sub> (10 mol %) in toluene upon heating, carbapenams<b> 10</b> were obtained in good yields.