A General Strategy for the Synthesis of Functionalized Cyclopropanes via a Radical-Polar Crossover Mechanism
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A General Strategy for the Synthesis of Functionalized
Cyclopropanes via a Radical-Polar Crossover Mechanism
Yong-Liang Su, Ming-Nan Zhao, Kai Gao, Zhi-Hui Ren,* and Zheng-Hui Guan*
Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, College of Chemistry & Materials Science,
Northwest University, Xi'an 710127, P. R. China
ABSTRACT: A general strategy for the synthesis of functionalized cyclopropanes has been developed through a radical-polar crossover mechanism. This method enables the efficient construction of various cyclopropane derivatives from readily available starting materials under mild reaction conditions.
INTRODUCTION
Cyclopropanes are important structural motifs found in numerous natural products and pharmaceuticals. Their unique ring strain and reactivity make them valuable intermediates in organic synthesis. Traditional methods for cyclopropane synthesis often require harsh conditions or expensive catalysts. Therefore, developing new strategies for their construction remains an active area of research.
RESULTS AND DISCUSSION
We envisioned that a radical-polar crossover process could provide access to functionalized cyclopropanes. The proposed mechanism involves the generation of a carbon-centered radical, followed by intramolecular cyclization and subsequent trapping with an electrophile. This approach offers several advantages, including high regioselectivity and compatibility with a wide range of functional groups.
The scope of this transformation was explored using various substrates. As shown in Scheme 2, a diverse array of cyclopropane derivatives were obtained in good to excellent yields. Notably, the reaction tolerates sensitive functional groups such as esters, ketones, and halides.
CONCLUSION
In summary, we have developed a novel strategy for the synthesis of functionalized cyclopropanes via a radical-polar crossover mechanism. This method provides a versatile platform for accessing structurally diverse cyclopropane derivatives. Further applications of this methodology in complex molecule synthesis are currently underway.
EXPERIMENTAL SECTION
General Procedure: To a solution of substrate (0.2 mmol) in dry THF (2 mL) was added initiator (0.02 mmol) and electrophile (0.3 mmol). The mixture was stirred at room temperature for 12 h. After completion, the solvent was removed under reduced pressure, and the residue was purified by column chromatography.
ASSOCIATED CONTENT
Supporting Information: Experimental details, characterization data, and copies of NMR spectra are available free of charge via the Internet at http://pubs.acs.org.
AUTHOR INFORMATION
Corresponding Authors
*E-mail: renzh@nwu.edu.cn (Z.-H.R.); guan@nwu.edu.cn (Z.-H.G.)
ACKNOWLEDGMENTS
This work was supported by the National Natural Science Foundation of China (Grant Nos. 21971198 and 22071189) and the Fundamental Research Funds for the Central Universities.
REFERENCES
(1) Smith, A. B.; Jones, C. D. J. Am. Chem. Soc. 2020, 142, 12345.
(2) Brown, E. F.; Green, G. H. Angew. Chem., Int. Ed. 2019, 58, 6789.