Cleavage of oxygen–sulfur double bonds and carbon–sulfur bonds: unusual highly selective electrophilic addition of allenylic sulfoxides

Abstract

Selective cleavage and formation of covalent bonds is an everlasting topic in the science of synthesis. Recently, much attention has been paid to the activation and functionalization of inert covalent chemical bonds such as C–H, C–O, C–Cl bonds, etc. In this edge article, we report that hydrogen bonding may mediate efficient and highly selective cleavage of OS and C–S bonds in 1,2-allenyl sulfoxides with I₂ and BnSH, which transfer the oxygen to the adjacent allenylic carbon atom forming a ketone or aldehyde carbonyl functionality with one CC bond in the allene moiety remaining in a highly stereoselective manner. This method provides a general and highly stereoselective route to the synthetically important yet difficult to prepare polysubstituted enals or enones.