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In this paper, a NaOtBu-mediated synthesis approach was developed for direct amidation of unactivated esters with amines under transition-metal-free and solvent-free conditions, affording a series of amides in good to excellent yields at room temperature. In particular, an environmentally friendly and practical workup procedure, which circumvents the use of organic solvents and chromatography in most cases, was disclosed. Moreover, the gram-scale production of representative products 3a, 3w and 3au was efficiently realized by applying operationally simple, sustainable and practical procedures. Furthermore, this approach was also applicable to the synthesis of valuable molecules such as moclobemide (a powerful antidepressant), benodanil and fenfuram (two commercial agricultural fungicides). These results demonstrate that this protocol has the potential to streamline amide synthesis in industry. Meanwhile, quantitative green metrics of all the target products were evaluated, implying that the present protocol is advantageous over the reported ones in terms of environmental friendliness and sustainability. Finally, additional experiments and computational calculations were carried out to elucidate the mechanistic insight of this transformation, and one plausible mechanism was provided on the basis of these results and the related literature reports.

Oxazolidinones and α-hydroxyl ketones are two series of fine chemicals that have been generally utilized in biological, pharmaceutical, and synthetic chemistry. Herein, a AgNO3/ionic liquid (IL) catalytic system was developed for the simultaneous synthesis of these compounds through the atom-economical three-component reactions of propargyl alcohols, 2-aminoethanols, and CO2. Notably, this system behaved excellent catalytic activity with the lowermost metal loading of 0.25 mol%. Meanwhile, it is the first reported metal-catalyzed system that could efficiently work under atmospheric CO2 pressure and be recycled at least five times. Evaluation of the green metrics proved the AgNO3/IL-catalyzed processes to be relatively more sustainable and greener than the other Ag-catalyzed examples. Further mechanistic investigations revealed the derivative active species of N-heterocyclic carbene (NHC) silver complexes and CO2 adducts generated during the process. Subsequently, their reactivity in this reaction was assessed for the first time, which was finally identified as beneficial for the catalytic activity.

α-Hydroxy ketones are a series of biologically active fragments in nature as well as important synthons for organic chemistry. Herein, an AgOAc/1-ethyl-3-methylimidazolium acetate ionic liquid syst...

With the aim of profitable conversion of carbon dioxide (CO2) in an efficient, economical, and sustainable manner, we developed a CuBr/ionic liquid (1-butyl-3-methylimidazolium acetate) catalytic system that could efficiently catalyze the three-component reactions of propargylic alcohols, 2-aminoethanols, and CO2 to produce 2-oxazolidinones and α-hydroxy ketones. Remarkably, this catalytic system employed lower metal loading (0.0125–0.5 mol%) but exhibited the highest turnover number (2960) ever reported, demonstrating its excellent activity and sustainability. Moreover, our catalytic system could efficiently work under 1 atm of CO2 pressure and recycle among the metal-catalyzed systems.