Corey-Kim oxidation

What is Corey-Kim oxidation?

In 1972, Corey and Kim reported a reaction that has come to be known as the Corey-Kim oxidation. This reaction is used to prepare aldehydes and ketones by oxidizing primary and secondary alcohols through their dimethylalkoxysulfonium salts.

When a base is added, the salt undergoes an intramolecular rearrangement to form aldehydes and ketones, depending on whether the alcohol was primary or secondary, respectively. The Corey-Kim oxidation is efficient, highly selective, and operationally simple.

Corey-Kim oxidation - general reaction scheme
Corey-Kim oxidation

To form the dimethylalkoxysulfonium salts on a large reaction scale, dimethylsulfide and chlorine are used. However, on a laboratory scale, a more convenient method involves generating the dimethylchlorosulfonium salt from N-succinimide chloride (or N-chlorosuccinimide, NCS) and dimethylsulfide. This method avoids the formation of hydrogen chloride and is known as the Corey-Kim reagent. It provides milder oxidation conditions and cleaner products.

Upon treatment with a base, the dimethylchlorosulfonium salt cleaves intramolecularly, yielding aldehydes and ketones. The use of 6-morpholinohexan-1-thiol ether or dodecyl methyl sulfide as a substitute for dimethylsulfide results in an odorless oxidation condition.

Additionally, the Corey-Kim reagent allows for a new methylation of an unsaturated bond from the nucleophilic addition of carbanion followed by treatment with Raney nickel.