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| Type |
Poster Presentation |
| Area |
Organic Chemistry |
| Room No. |
Event Hall |
| Time |
4월 19일 (목요일) 11:00~12:30 |
| Code |
ORGN.P-411 |
| Subject |
Asymmetric Phase-Transfer-Catalyzed Synthesis of Chiral Carboxy-Substituted 2-Isoxazolines by Cascade Oxa-Michael-Cyclization Reactions |
| Authors |
Heun-Jong Ha, Chang-Woo Cho*
Department of Chemistry, Kyungpook National University, Korea
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| Abstract |
2-Isoxazolines are an important class of heterocycles found in natural products, pharmaceuticals and agrochemicals displaying a variety of potent biological activities. In addition, 2-isoxazolines have been widely used as versatile synthons and chiral ligands in synthetic organic chemistry. For this reason, 2-isoxazoline synthesis has attracted significant attention. In particular, the asymmetric synthesis of optically pure 2-isoxazolines has been a subject of active research. As an example of the importance of enantiopure 2-isoxazolines, biological evaluation of the antiparasitic isoxazoline Bravecto (fluralaner) revealed that only the S enantiomer of Bravecto is active and the R enantiomer is inactive. In addition, it was reported that only the (S)-methiozolin displayed herbicidal activities against grass weeds. Interestingly, (R)-methiozolin showed no herbicidal activities. Methiozolin has been commercialized as a racemic herbicide displaying an efficacious and toxicologically favorable activity against grass weed in turf grass. Therefore, owing to the environment-friendly and atom-economic importance, development of an enantioselective route for the efficient synthesis of (S)-methiozolin is highly desirable. Here, we report an asymmetric phase-transfer-catalyzed cascade oxa-Michael‒cyclization reaction of various β-carboxy-substituted α,β-unsaturated ketones with hydroxylamine that affords the desired chiral carboxy-substituted 2-isoxazolines in good yields with excellent enantioselectivities. |
| E-mail |
heunjong@knu.ac.kr |
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121st General Meeting of the KCS