Valorization of CO2 into N‐alkyl Oxazolidin‐2‐ones Promoted by Metal‐Free Porphyrin/TBACl System: Experimental and Computational Studies

Caterina Damiano,Emma Gallo,Paolo Sonzini,Gabriele Manca

doi:10.1002/ejoc.202100365

Caterina Damiano, Emma Gallo + Show 2 more

Open Access

https://doi.org/10.1002/ejoc.202100365

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Abstract

AbstractThe cycloaddition of CO2 to N‐alkyl aziridines was efficiently promoted by the convenient TPPH2/TBACl binary catalytic system. The metal‐free procedure was effective for the synthesis of differently substituted N‐alkyl oxazolidin‐2‐ones in yields up to 100 % and excellent regioselectivities (up to 99 %). The mechanism of the reaction was proposed based on a DFT study which indicated the formation of an adduct between TPPH2 and TBACl as the effective catalytic active species.

Highlights

The progressive increasing of greenhouse gas emissions is causing a constant rising in average global temperatures which is responsible for extreme events all over the world
The catalyzed CO2 cycloaddition to aziridines usually occurs in the presence of an electrophile/nucleophile (E/Nu) binary system, where the electrophile is in charge of coordinating the nitrogen aziridine atom in order to promote the opening of the aziridine ring by the nucleophilic species (Scheme 1)
In the last few years we have studied the performance of porphyrin-based protocols in catalyzing the CO2 cycloaddition to both epoxides and aziridines

Summary

Introduction

The progressive increasing of greenhouse gas emissions is causing a constant rising in average global temperatures which is responsible for extreme events all over the world. Among all catalytic systems, which promote the CO2 cycloaddition to three-membered rings (epoxides and aziridines), those employing porphyrin metal catalysts in the presence of LB co-catalysts[15b, 17] performed well under low CO2 pressures and temperatures.

Results

Conclusion