Palladium-Catalyzed Asymmetric Cycloadditions of Vinylcyclopropanes and in Situ Formed Unsaturated Imines: Construction of Structurally and Optically Enriched Spiroindolenines
Organic Letters2014Vol. 17(1), pp. 150–153
Citations Over TimeTop 10% of 2014 papers
Abstract
A palladium-catalyzed (3 + 2) cycloaddition of vinyl cyclopropane and α,β-unsaturated imines generated in situ from aryl sulfonyl indoles is reported. The reaction proceeds with high diastereoselectivity to provide the optically enriched spirocyclopentane-1,3'-indolenines in up to 74% yield and with up to 97% ee, which contains an all-carbon quaternary center and two tertiary stereocenters. The reaction involves a first conjugate addition of the carbon anion of zwitterionic π-allylpalladium complex from vinyl cyclopropane to the in situ formed unsaturated imine followed by a palladium-catalyzed intramolecular C3-allylation of indole.
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