Lemieux‐Johnson Reagent / Lemieux–Johnson Oxidation
The Lemieux-Johnson reagent is a combination of osmium tetroxide (OsO4) and sodium periodate (NaIO4) used for oxidative cleavage of carbon-carbon double bonds in alkenes. This cleavage produces aldehydes or ketones, similar to the results of reductive ozonolysis. This is also known as Lemieux–Johnson oxidation.
Mechanism of Lemieux–Johnson Oxidation
The reaction involves the formation of cyclic osmate ester, which undergoes oxidative cleavage with NaIO4 to give the dicarbonyl compounds
The reaction involves two steps:
Step-1: Dihydroxylation: OsO4 adds hydroxyl groups across the double bond (syn-addition), forming a 1,2-diol (cis-diol not trans-diol).
Step-2: Oxidative Cleavage: NaIO4 then cleaves the diol, forming the aldehydes or ketones.
