Thiol-Promoted Selective Addition of Ketones to Aldehydes

Regev Parnes, Chemistry, BGU, Beer-Sheva, Israel


A simple and efficient thiol-mediated addition of ketones to aromatic and aliphatic aldehydes is reported. This thermodynamically controlled Pummerer/aldol reaction, which can tolerate both moisture and protic functional groups, provides a direct entry to syn – β -thioketones in high chemo- and regioselectivity . Mechanistic studies revealed that selective transformation of the aldehyde to an electrophilic thionium ion species concurrent with the generation of a nucleophilic vinyl sulfide coupling partner from the ketone is imposing cross-coupling over dimerization.