Rhodium-Catalyzed Synthesis of 3-Hydroxy-β-lactams via Oxonium Ylide Generation: Three-Component Reaction between Azetidine-2,3-diones, Ethyl Diazoacetate, and Alcohols

3-Substituted-3-hydroxy-β-lactams, with two new adjacent stereogenic centers, have been prepared in a single step by a rhodium-catalyzed, three-component reaction between azetidine-2,3-diones, ethyl diazoacetate, and alcohols. Good to moderate stereoselectivity was obtained depending on the alcohol used. The stereochemistry of the new centers has been undoubtedly assigned by single crystal X-ray diffraction.