Ionic Liquid-Catalyzed C–S Bond Construction using CO₂ as a C1 Building Block under Mild Conditions: A Metal-Free Route to Synthesis of Benzothiazoles

Abstract

The construction of the C−S bond using CO 2 as a C1 feedstock can be considered as a green route for the synthesis of S-containing compounds and is of great significance. Herein, we report the acetate-based ionic liquids (ILs)-catalyzed synthesis of benzothiazoles via cyclization of 2-aminothiophenols with CO 2 and hydrosilane under mild conditions (e.g., 60°C, 0.5 MPa). It was found that the IL (e.g., 1-butyl-3-methylimidazolium acetate, [Bmim][OAc]) served as a multifunctional catalyst with activating CO 2 and hydrosilane to form a formoxysilane intermediate, as well as simultaneously activating 2-aminothiophenols through a hydrogen bond, finally resulting in the production of benzothiazoles. [Bmim][OAc] showed the best performance, and a series of benzothiazoles were obtained in high yields. To the best of our knowledge, this is the first protocol for the synthesis of benzothiazoles using CO 2 as a C1 building block under metalfree and mild conditions.

Organic Base-Catalyzed C–S Bond Construction from CO2: A New Route for the Synthesis of Benzothiazolones

“…The formation of the C-S bond is one of the important transformations in organic synthesis [23,24], and the construction of C-S bonds using CO 2 as a C1 source is an interesting topic. In our recent efforts, we discovered a new route for the synthesis of benzothiazoles via the reaction of 2-aminothiophenols with CO 2 and hydrosilanes, which was the first body of work describing the construction of C-S bonds from CO 2 [25,26]. It is worth mentioning that a byproduct, benzothiazolone, was detected in minute amounts along with benzothiazole, which was formed via Recently, organic bases were widely applied to CO 2 -joined reactions with highly efficient catalytic activity.…”

Advances in Porous Adsorbents for CO2 Capture and Storage

“…Nevertheless, being cheap and easy availability, CO 2 is enriched as C1 feedstock and has broad scope of serving as C1 chemistry to produce important products e.g. fuels, commodity chemicals, agrochemicals, valuable materials and so on [13].…”

Effect of molten carbonate composition on the generation of carbon material

“…11 Note, that CO 2 is not only a greenhouse gas needed to be captured and stored, but an ideal C1 feedstock that can be applied in the eld of synthesizing carbonaceous products. 12,13 Therefore, the preparation of value-added, carbonaceous chemicals from CO 2 emitted by industry is both an economic and environmental-friendly option that could alleviate the pressure of environmental degradation and the energy crisis simultaneously.…”