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We present a novel deoxygenation method for heterocyclic Noxides utilizing iodide as a catalyst. Iodide acts as a reducing catalyst that is regenerated by formic acid, which also serves as a Brønsted activator and solvent. The method demonstrates high efficiency and excellent selectivity in the reduction of a variety of heterocyclic N-oxides and tertiary amines. Our computational DFT investigation revealed that the reduction mechanism entails a direct interaction between iodide and the oxygen of the N-oxide within a Mg2+/formic acid framework, resulting in the formation of the N-heterocycle and the release of a hypoiodite unit. Additionally, a molecular mechanism for the regeneration of iodide from hypoiodite, facilitated by formic acid, is suggested. This method provides an environmentally friendly approach for the deoxygenation of N-oxides and related species. [ABSTRACT FROM AUTHOR]

This review provides a comprehensive overview of strategies and methodologies for reducing C−O and heteroatomic−oxygen bonds (N−O, S−O, P−O) using I2/I−, as well as other synthetically relevant bonds such as C−C, N−N, C−N, C−X, C−S. It highlights and discusses most of the mechanistic details provided by the original authors. Selected examples of other halides (Br and Cl) as reductants are also covered. [ABSTRACT FROM AUTHOR]