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. 2020 Aug 9;25(16):3621.
doi: 10.3390/molecules25163621.

Base-Promoted Annulation of Amidoximes with Alkynes: Simple Access to 2,4-Disubstituted Imidazoles

Hina Mehmood  1 , Muhammad Asif Iqbal  1 , Le Lu  1 , Ruimao Hua  1
Affiliations

Base-Promoted Annulation of Amidoximes with Alkynes: Simple Access to 2,4-Disubstituted Imidazoles

Hina Mehmood et al. Molecules. .

Abstract

An efficient construction of imidazole ring by a Cs2CO3-promoted annulation of amidoximes with terminal alkynes in DMSO has been developed. This protocol provides a simple synthetic route with high atom-utilization for the synthesis of 2,4-disubstituted imidazoles in good yields under transition-metal-free and ligand-free conditions. Internal alkynes can also undergo the annulation to give 2,4,5-trisubstituted imidazoles.

Keywords: 2,4-disubstituted imidazoles; alkynes; amidoximes; annulation; base-promoted.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Examples of commercial drugs with imidazole skeleton.
Scheme 1
Scheme 1
Synthesis of diverse position-substituted imidazoles from alkynes.
Scheme 2
Scheme 2
Substrate scope of imidazole synthesis a.
Scheme 3
Scheme 3
Proposed mechanism for the formation of imidazoles.
Figure 2
Figure 2
Free energy profile for the base-promoted annulation of 1a with 2a affording 3aa.
See this image and copyright information in PMC

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