Diastereoselective Synthesis of β‐Lactam–Oxindole Hybrids Through a Three‐Component Reaction of Azetidine‐2,3‐diones, α‐Diazo‐oxindoles, and Alcohols Catalyzed by [Rh₂(OAc)₄]

Abstract

Abstract β‐Lactam–oxindole hybrids have been synthesized in good yields in a one‐pot procedure through efficient and stereoselective capture of an oxonium ylide with azetidine‐2,3‐diones. The reaction allows high to moderate control of stereoselectivity, depending on the 3‐diazo‐oxindole precursor and the hydroxylic compound used. Two new quaternary stereogenic centers were formed; the stereochemistry at the C‐3 quaternary center was controlled by a bulky substituent at C‐4, whereas the stereoselectivity in the adjacent second quaternary stereogenic center was controlled by the α‐diazo‐oxindole. The stereochemistry of both quaternary centers has been unambiguously assigned by single‐crystal X‐ray diffraction.