TEMPO and its Derivatives: Synthesis and Applications

The radical TEMPO (2,2,6,6-tetramethylpiperidine 1-oxyl radical) and its derivatives are well-established catalysts for oxidation processes, and now used extensively in organic synthesis and industrial applications as a mild, safe, and economical alternative to heavy metal reagents as highly selective oxidation catalysts. In this review, we attempt to fully review the recent advances in the syntheses of TEMPO and its derivatives as well as their applications in recent years. The synthesis of TEMPO and its derivatives are discussed first. The largest section focuses on their application as stoichiometric and catalytic oxidants in organic synthesis, particularly focusing on the formation of C-C, C-O, C=O, C-N, and C=N bond. Simultaneously, the oxidation of alcohols to their corresponding carbonyl compounds also is commented briefly. The last section discusses the application of the TEMPO-catalyzed reactions in the total syntheses of natural products.