nBu₄NI-catalyzed oxidative cross-coupling of carbon dioxide, amines, and aryl ketones: access to O-β-oxoalkyl carbamates

Abstract

The first nBuNI-catalyzed oxidative cross-coupling reaction of carbon dioxide, amines and arylketones has been successfully developed by using TBHP as the oxidant, providing an efficient, atom-economical and metal-free strategy for the synthesis of a range of O-β-oxoalkyl carbamates.

Transition Metal‐Free Synthesis of Carbamates Using CO2 as the Carbon Source

“…These results provided valuable insights in this type of reactions and especially, new point of view about the effect of DMSO for the synthesis of carbamates. In fact, very similar findings were observed by our group and by Jiang and co‐workers when both of them reported the efficient benefits of using DMSO for the synthesis of carbamates [28,29] …”

“…In 2017, the group of Jiang collaborated with the Qu and Yuan groups to report a nBu 4 NI-catalyzed oxidative cross coupling reactions to form O-β-oxoalkyl carbamates by utilizing aryl ketones as the starting material. [29] This was adding a new synthetic strategy to the spectrum of metal-free carbamate ChemSusChem synthesis. After optimizations, they could show that nBu 4 NI as a catalyst and tert-butyl hydroperoxide (TBHP) as an oxidant can provide excellent yields in the solvent mixtures of DMF and DMSO.…”

Electrocatalytic Fixation of Carbon Dioxide with Amines and Arylketones

“…Accordingly, the strategy of carbamates synthesis from a C−H functionalization attracted the attention of the chemists. For instance, Yuan's group employed this strategy to synthesize carbamates under catalysis of n ‐Bu 4 NI (Scheme c), in which the reaction was conducted at 90 °C under 3 MPa of CO 2 . In comparison with the conventional redox reactions, electrochemical synthesis is usually more sustainable and environmental friendship and is abundantly employed in various organic synthesis over last decade .…”

Iridium-Catalyzed Three-component Coupling Reaction of Carbon Dioxide, Amines, and Sulfoxonium Ylides

“…Sulfoxonium ylides, which are bench-stable compounds and safer to be synthesized, have recently been extensively explored as safe alternatives to diazo compounds in transition metal-catalyzed carbon–carbon bond- and carbon–heteroatom bond-forming reactions. , However, to the best of our knowledge, the use of sulfoxonium ylides for the construction of organic carbamates has not yet been reported. As our continuous effort in the development of efficient methods for the transformation of carbon dioxide into carbamates, we envisioned that a direct route to O -β-oxoalkyl carbamates might be achieved by transition metal-catalyzed three-component coupling between CO 2 , amines, and sulfoxonium ylides (Scheme ). The reaction pathway was hypothesized as follows: initially, sulfoxonium ylide reacts with metal catalyst to give a metal–carbene intermediate D , which would be attacked nucleophilically by in situ generated carbamate anion E to generate intermediate F .…”