Expedient Organocatalytic Syntheses of 4-Substituted Pyrazolidines and Isoxazolidines
AbstractThe efficient organocatalytic synthesis of heterocyclic systems of biological relevance is a subject of growing interest. We have found that the pyrrolidine/benzoic acid-catalyzed reaction of α-substituted propenals such as methacrolein, 2-benzylpropenal and 2-(n-hexyl)propenal with activated hydrazines takes place in very good yields (83%–99.6%) under very mild conditions to afford 4-substituted pyrazolidin-3-ols (as diastereomer mixtures); subsequent oxidation with PCC affords the corresponding-4-substituted-3-pyrazolidinones in essentially quantitative yields. In a similar way, 4-substituted isoxazolidinones are obtained with N-Cbz-hydroxylamine as a reagent. The use of chiral diarylprolinol trimethylsilyl ethers as catalysts allows the synthesis of several of these compounds in optically active form, in some cases with excellent enantioselectivity (up to 96:4 er). A preliminary evaluation of the biological activity shows that some of these compounds exhibit interesting antibacterial and antifungal activities. View Full-Text
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Yousfi, T.; Elliott, A.; Hanane, M.; Merdes, R.; Moyano, A. Expedient Organocatalytic Syntheses of 4-Substituted Pyrazolidines and Isoxazolidines. Molecules 2016, 21, 1655.
Yousfi T, Elliott A, Hanane M, Merdes R, Moyano A. Expedient Organocatalytic Syntheses of 4-Substituted Pyrazolidines and Isoxazolidines. Molecules. 2016; 21(12):1655.Chicago/Turabian Style
Yousfi, Tarek; Elliott, Alysha; Hanane, Messiad; Merdes, Rachid; Moyano, Albert. 2016. "Expedient Organocatalytic Syntheses of 4-Substituted Pyrazolidines and Isoxazolidines." Molecules 21, no. 12: 1655.
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