Hypervalent iodine(III)-promoted intermolecular C-C coupling of vindoline with β-ketoesters and related substrates.

The regioselective intermolecular coupling reaction of vindoline with a wide range of substrates including β-ketoesters, β-diketones, β-ketoaldehydes, β-ketonitriles, malononitriles, and β-cyanoesters provides an opportunity for the synthesis of vinblastine analogues containing deep-seated changes in the upper velbanamine subunit. The transition-metal-free hypervalent iodine(III)-promoted intermolecular sp(3)/sp(2) coupling, representing a special class of selective C-H activation with direct carbon-carbon bond formation, proceeds with generation of a quaternary center capable of incorporation of the vinblastine C16' methyl ester and functionalized for subsequent divergent heterocycle introduction.