Access to a welwitindolinone core using sequential cycloadditions.

Barry M Trost, Patrick J McDougall

Index: Org. Lett. 11(16) , 3782-5, (2009)

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Abstract

A concise approach to the core skeleton of the welwitindolinone alkaloids was developed on the basis of sequential cycloaddition reactions. First, a palladium catalyzed enantioselective [6 + 3] trimethylenemethane cycloaddition onto a tropone nucleus was used to generate the requisite bicyclo[4.3.1]decadiene. Subsequent modifications to the cycloadduct allowed for an intramolecular [4 + 2] cycloaddition to generate the oxindole and complete the core of the natural product family.