Highly efficient "on water" catalyst-free nucleophilic addition reactions using difluoroenoxysilanes: Dramatic fluorine effects

A remarkable fluorine effect on "on water" reactions is reported. The C-FaH-O interactions between suitably fluorinated nucleophiles and the hydrogen-bond network at the phase boundary of oil droplets enable the formation of a unique microstructure to facilitate on water catalyst-free reactions, which are difficult to realize using nonfluorinated substrates. Accordingly, a highly efficient on water, catalyst-free reaction of difluoroenoxysilanes with aldehydes, activated ketones, and isatylidene malononitriles was developed, thus leading to the highly efficient synthesis of a variety of α,α- difluoro-β-hydroxy ketones and quaternary oxindoles. It's on! The C-FaH-O interactions between suitably fluorinated nucleophiles and a hydrogen-bond network at the phase boundary of an oil droplet facilitate "on water" catalyst-free reactions. Accordingly, the title reaction of difluoroenoxysilanes with aldehydes, activated ketones, and isatylidene malononitriles was developed, thus leading to α,α-difluoro-β-hydroxy ketones and quaternary oxindoles.