Amino Acid Derived Hydrogen Bond Donor (HBD) Catalyst for the Synthesis of Cyclic Carbonates and Cyclic Dithiocarbonates: Experimental and Computational Studies

In this research work, Amino acid derived functionalized compounds have been designed, synthesized, and utilized as Hydrogen Bond Donor (HBD) catalysts for the successful installation of CO₂ and CS₂ in epoxide for the synthesis of cyclic carbonates and dithiocarbonates. Ambient and solvent-free reaction condition with the use atmospheric CO₂ makes this catalytic domino method sustainable.

Abstract

Amino acid derived functionalized compounds have been designed, synthesized, and utilized as hydrogen bond donor (HBD) catalysts for the successful installation of CO₂ and CS₂ in epoxide for the synthesis of corresponding cyclic carbonates and dithiocarbonates. Here, the structural features of the catalysts play pivotal role for the viable utilization of the C-1 synthons. The rational design of the HBD catalysts involved strategic derivatization of the amine group of the amino acid ester to cater suitable noncovalent interactions with the substrate epoxide. Suitable hydrogen bonding interactions take place between the purposefully incorporated phenolic −OH groups present in the catalysts and the “O” atom of the epoxide. The syntheses of such amino acid derivatives involve sequential functional group modifications with expedient reaction steps. The catalytic activity of such novel amino acid ester derivatives was studied for CO₂ and CS₂ installation reactions with various epoxides. Excellent results were obtained in terms of selectivity and yield of the final products. Tetra-butyl ammonium iodide (TBAI) was used as a cocatalyst and the reactions were optimized in a very mild and solvent free condition. Overall, this research work demonstrates effective implementation of newly developed HBD catalysts in the one-pot, multi-steps domino reaction protocol.

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