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]

Article abstract of DOI:10.1002/ejoc.201101625

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. Densely functionalized β-lactam-oxindole hybrids have been prepared in a one-pot, multicomponent reaction between azetidine-2,3-diones, α-diazo-oxindoles, and alcohols. Two new stereogenic centers were formed; the stereochemistry at the new C-3 quaternary center was controlled by a bulky substituent at C-4, whereas the second new stereogenic center was controlled by the α-diazo-oxindole.