Assignment of E–Z-configurations of spiro-oxirane-oxindoles synthesized by rhodium(II) acetate-catalyzed reaction of ethyl diazoacetate with N-methylisatin. Issue 3 (15th March 2016) - Ngaski, Abubakar M.
ABSTRACT: The rhodium(II) acetate [Rh2 (OAc4 )]-catalyzed reaction of ethyl diazoacetate with N -methylisatin leads to the formation of diastereomeric oxiranes spiro-fused to N -methyl-2-oxindole together with 1, 3-dioxolane bis-spiro-fused to N -methyl-2-oxindole. The formation of ylide from the reaction of rhodium-carbenoid with C-3 carbonyl group of the N -methylisatin undergoing a 1, 3-cyclization, and a [3 + 2]-dipolar cycloaddition with another molecule of N- methylisatin, respectively, explains the formation of products. The application of nuclear overhauser effect spectroscopy to determine the E – Z -configurations of the spiro-oxirane-oxindoles is demonstrated.