Simple Copper Catalysts for the Aerobic Oxidation of Amines: Selectivity Control by the Counterion

Abstract

We describe the use of simple copper-salt catalysts in the selective aerobic oxidation of amines to nitriles or imines. These catalysts are marked by their exceptional efficiency, operate at ambient temperature and pressure,a nd allow the oxidation of amines without expensive ligands or additives. This study highlights the significant role counterions can play in controlling selectivity in catalytic aerobic oxidations.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under http://dx.Scheme 3. Kinetic isotope effects and control experiments.Scheme 4. Proposed mechanism. Angewandte Chemie Communications 15805

One‐Pot Copper‐Catalyzed Cascade Bicyclization Strategy for Synthesis of 2‐(1H‐Indol‐1‐yl)‐4,5‐dihydrothiazoles and 2‐(1H‐Indol‐1‐yl)thiazol‐5‐yl Aryl Ketones with Molecular Oxygen as an Oxygen Source

“…Inspired by the research described above, we herein report that we have achieved the first copper‐catalyzed cascade bicyclization reactions between o ‐alkynylphenyl isothiocyanates and propargylamine derivatives (Scheme c), despite the fact that amines are unstable to oxidants . Unlike previously reported reactions of similar substrates, these reactions afforded 2‐(1 H ‐indol‐1‐yl)‐4,5‐dihydrothiazoles rather than fused‐ring compounds .…”

Second-Order Biomimicry: In Situ Oxidative Self-Processing Converts Copper(I)/Diamine Precursor into a Highly Active Aerobic Oxidation Catalyst

“…The excess O 2 consumption, together with precedents for Cu-catalyzed dehydrogenation of secondary amines, 48 − 51 raised the possibility that the DBED ligand could be converted to a mono- or diimine derivative under the reaction conditions. Aliquots of the reaction mixture withdrawn at regular intervals were worked up in a manner that allowed analysis of the DBED ligand (see Figures S2–S4 ).…”

Copper Mediated Chemo‐ and Stereoselective Cyanation Reactions

“…The catalytic reaction was performed under facile conditions avoiding the utilization of expensive ligands and toxic solvents (See Figure 92). [99] …”

“…The catalytic reaction was performed under facile conditions avoiding the utilization of expensive ligands and toxic solvents (See Figure 92). [99] (4,4'-t Bu 2 bpy)CuI/ABNO(9-azabicyclo[3.3.1]nonan-3-one-Noxyl)/DMAPwas used as the efficient catalytic system for the selective aerobic synthesis of nitriles from amines under ambient reaction conditions. The catalytic system was compatible with a broad range of substrates like benzylic, allylic, and aliphatic amines (See Figure 93).…”