Synthesis of 3,4-Disubsituted Isoxazoles via Enamine [3+2] Cycloaddition
Qian-fa Jia, Pooi Ming Shurn Benjamin, Jiayao Huang, Zhiyun Du, Xi Zheng, Kun Zhang, Allan H. Conney, Jian Wang*
*Guang Dong University of Technology, Guang Dong, 510006, P. R. of China; Department of Chemistry, National University of Singapore, 117543, Singapore, Email: chmwangjnus.edu.sg
Q.-f. Jia, P. M. S. Benjamin, J. Huang, Z. Du, X. Zheng, K. Zhang, A. H. Conney, J. Wang, Synlett, 2013, 24, 79-84.
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Enamine-triggered [3+2]-cycloaddition reactions of aldehydes and N-hydroximidoyl chlorides in the presence of triethylamine gives 3,4,5-trisubstituted 5-(pyrrolidinyl)-4,5-dihydroisoxazoles. Subsequent oxidation of the cycloadducts offers a high yielding, regiospecific and metal-free synthetic route for the synthesis of 3,4-disubstituted isoxazoles.
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2-isoxazolines, isoxazoles, enamines, 1,3-dipoles, [3+2] cycloaddition, 1,3-dipolar cycloaddtion, Cope elimination, MCPBA