Water mediated trapping of active methylene intermediates generated by IBX-induced oxidation of Baylis–Hillman adducts with nucleophiles

Water proved to be an efficient solvent for oxidation of a Baylis–Hillman adduct with IBX. The generated product, a methylene intermediate, could be trapped in situ by many nucleophiles in water, such as styrenes, β-dicarbonyl compounds, benzamide and less reactive indoles. This strategy offers an alternative way to methylenylation of β-dicarbonyl compounds with formaldehyde for the formation of a methylene intermediate, thus allows the use of some nucleophiles that are chemically unstable to formaldehyde. The use of water as solvent, good recycling ability of IBX oxidant and wide substrate scopes make these reactions very attractive from the viewpoint of green chemistry.