Issue 7, 2024

Simple pyrazoles as efficient organocatalysts for alkyne–CO2 carboxylation and one-pot construction of heterocycles

Abstract

C–H carboxylation of alkynes with CO2 is a straightforward and atom-economical approach toward propiolic acids. Transition metal catalysis for this reaction has been intensively studied, but organocatalysis remains largely undeveloped. Here we disclose that simple pyrazoles are efficient bifunctional organocatalysts rivalling metal catalysts in promoting the carboxylation reaction. Organocatalytic carboxylation has been successfully utilized in orthogonal tandem catalysis for the one-pot construction of various heterocycles, including pyranones, quinazinones, pyridones, isoxazolo[3,2-a]isoindolones and imidazoles. In the synthesis of pyranones and quinazinones, we identified for the first time that the [3 + 3] cyclization between propiolates and acyl-activated methylene compounds involves C-to-C 1,3-acyl migration. The results illustrate new prospects for organocatalytic CO2 conversion and heterocycle synthesis.

Graphical abstract: Simple pyrazoles as efficient organocatalysts for alkyne–CO2 carboxylation and one-pot construction of heterocycles

Supplementary files

Article information

Article type
Research Article
Submitted
04 Feb 2024
Accepted
12 Feb 2024
First published
20 Feb 2024

Org. Chem. Front., 2024,11, 2062-2069

Simple pyrazoles as efficient organocatalysts for alkyne–CO2 carboxylation and one-pot construction of heterocycles

L. Zhang, G. Li, E. Xing, Y. Liu, C. Jin, Z. Du, Y. Xu, D. Zhang and E. Gao, Org. Chem. Front., 2024, 11, 2062 DOI: 10.1039/D4QO00237G

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