The Kharasch–Sosnovsky reaction is a method that involves using a copper or cobalt salt as a catalyst to oxidize olefins at the allylic position, subsequently condensing a peroxy ester (e.g. tert-Butyl peroxybenzoate) or a peroxide resulting in the formation of allylic benzoates or alcohols via radical oxidation.[1] This method is noteworthy for being the first allylic functionalization to utilize first-row transition metals and has found numerous applications in chemical and total synthesis.[2] Chiral ligands can be used to render the reaction asymmetric, constructing chiral C–O bonds via C–H bond activation.[3] This is notable as asymmetric addition to allylic groups tends to be difficult due to the transition state being highly symmetric. The reaction is named after Morris S. Kharasch and George Sosnovsky who first reported it in 1958.[4] This method is noteworthy for being the first allylic functionalization to utilize first-row transition metals and has found numerous applications in chemical and total synthesis.[2]
In the original work on Kharasch-Sosnovsky oxidation,
Kharasch and Sosnovsky observed the selective formation of the branched product over the linear product with
1-octene in a ratio of 99:1.
[1]
It is notable that the reaction favors the thermodynamically less stable terminal alkene. Mechanistic investigations later suggested that the reaction proceeds through a 7-membered ring organo-copper (III) species in a pericyclic reaction, resulting in an unrearranged terminal alkene product.
