Toward a General Protocol for Catalytic Oxidative Transformations Using Electrochemically Generated Hypervalent Iodine Species

Abstract

A simple catalytic electrosynthetic protocol for oxidative transformations mediated by hypervalent iodine reagents has been developed. In this protocol, electricity drives the iodine(I)/iodine(III) catalytic cycle enabling catalysis with in situ generated hypervalent iodine species, thereby eliminating chemical oxidants and the inevitable chemical waste associated with their mode of action. In addition, no added electrolytic salts are needed in this process. The developed method has been validated using two different hypervalent iodine-mediated transformations: (i) the oxidative cyclization of N-allylic and N-homoallylic amides to the corresponding dihydrooxazole and dihydro-1,3-oxazine derivatives, respectively, and (ii) the α-tosyloxylation of ketones. Both reactions proceeded smoothly under the developed catalytic electrosynthetic conditions without reoptimization, featuring a wide substrate scope and excellent functional group tolerance. In addition, scale-up to gram-scale and catalyst recovery were easily achieved maintaining the high efficiency of the process.

Overcoming Challenges in Electrosynthesis Using High‐Throughput Electrochemistry: Hypervalent Iodine‐Mediated Phenol Dearomatization, a Case Study

“…One advantage of electrochemical reactions over their classical counterpart is therefore that they are often compatible with catalytic turnover. Many instances of HVI electrocatalysis have been demonstrated, using substoichiometric loading of mediator often ranging between 25 % or 30 % equivalent relative to the substrate [17,29] . With this in mind, we evaluated the effect of lowering mediator loading to assess the feasibility of an electrocatalytic mechanism.…”

“…Forefront developments in HVI mediated electrosynthesis point towards catalytic usage of specifically designed HVI mediators [2,17] . Motivated by this direction, our investigation aimed to adapt the dearomatization of phenol 1 to an electrocatalytic mechanism, i. e .…”

“…Forefront developments in HVI mediated electrosynthesis point towards catalytic usage of specifically designed HVI mediators. [2,17] Motivated by this direction, our investigation aimed to adapt the dearomatization of phenol 1 to an electrocatalytic mechanism, i. e. with substoichiometric loading of aryl iodide precursors. Simultaneously, this endeavor provided an opportunity to validate the capabilities of the HTE reactor.…”

Hypervalent Halogen Compounds in Electrochemical Reactions: Advantages and Prospects

“…Moran and Elsherbini very recently disclosed some further developments in iodine(I)/iodine(III) catalytic processes in which cyclizations and α ‐oxytosylations have been investigated (Scheme 16). [53] Initially, iodobenzene 63 is oxidized in the presence of HFIP to 64 , which undergoes ligand exchange with tosylic acid to form the more stable Koser's reagent 65 . Compound 65 is the active iodine(III) reagent which interacts with the corresponding substrate.…”

Electrochemical Trifluoromethylation and Sulfonylation of N-Allylamides: Synthesis of Oxazoline Derivatives

“…Electrochemical organic synthesis has been used as an important synthetic tool due to its green and sustainable nature . In recent years, studies on the electrosynthesis of oxazolines from N -allylamide by incorporating the halogen, thiol, selenium, alkynyl, or tosyloxyl group have been documented. It is noted that the electrochemical synthesis of oxazolines containing a trifluoromethyl or sulfonyl group has not been reported.…”