Iodine‐Catalyzed Oxidative Rearrangement of Amines to α‐Amino Acetals and α‐Amino Aldehydes

Abstract

A protocol for iodine-catalyzed oxidative rearrangement of tertiary and secondary amines has been developed. This metal-free protocol provides an atom-economical, efficient access to synthetically useful a-amino acid derivatives from readily available acyclic and cyclic tertiary or secondary amines.

Iodine‐Mediated Coupling of Cyclic Amines with Sulfonyl Hydrazides: an Efficient Synthesis of Vinyl Sulfone Derivatives

“…Subsequently, the hydrogen atom at the α‐carbon of substrate 1 a is abstracted by the tert ‐butoxyl radical to form α‐amino radical A . Then, the single‐electron oxidation of radical A by iodine provides iminium ion B , which is deprotonated to afford enamine C [10] . In the meantime, the tert ‐butoxyl radical abstracts a hydrogen atom from sulfonyl hydrazide 2 a , which initiates the generation of sulfonyl radicals ( D ) and the release of molecular nitrogen [5f,9d,11] .…”

“…Subsequently, the hydrogen atom at the α-carbon of substrate 1 a is abstracted by the tert-butoxyl radical to form α-amino radical A. Then, the single-electron oxidation of radical A by iodine provides iminium ion B, which is deprotonated to afford enamine C. [10] In the meantime, the tert-butoxyl radical abstracts a hydrogen atom from sulfonyl hydrazide 2 a, which initiates the generation of sulfonyl radicals (D) and the release of molecular nitrogen. [5f,9d,11] Afterwards, the radical addition reaction of D and enamine C generates carbon radical E. Finally, radical E reacts with iodine to generate iodosulfone F, which undergoes HI elimination assisted by NaHCO 3 to afford the final product 3 a.…”

Aerobic α,β-C(sp3)–H Bond Difunctionalization and C–N Bond Cleavage of Triethylamine: Difunctional Ammonium Iodide Enabling the Regioselective Synthesis of 4-Arylpyrimido[1,2-b]indazoles

“…However, no conversion occurred when Et 3 N was replaced by metaldehyde and enamine ( 6 ) (Scheme c and d). These results strongly demonstrated that the imine intermediate from Et 3 N was preferentially captured by 3-aminoindazoles and prevented from converting to its enamine form under the NH 4 I-mediated aerobic oxidative conditions . Based on the blank experiments, it was confirmed that NH 4 I and molecular oxygen were indispensable for this transformation (Scheme e and f).…”