Stereoselective reduction of the bioactive 19- nor -clerodane trans -dehydrocrotonin by using sodium borohydride and cerium (III) chloride as a catalyst
| Autor: | Maria Aparecida Medeiros Maciel, Adailton J. Bortoluzzi, Breno Almeida Soares, Rosane Nora Castro, Caio L. Firme |
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| Rok vydání: | 2018 |
| Předmět: |
010405 organic chemistry
Organic Chemistry 010402 general chemistry 01 natural sciences Medicinal chemistry 0104 chemical sciences Analytical Chemistry Catalysis Inorganic Chemistry Solvent Sodium borohydride chemistry.chemical_compound chemistry Decalin Organic chemistry Moiety Reactivity (chemistry) Methanol Cerium(III) chloride Spectroscopy |
| Zdroj: | Journal of Molecular Structure. 1154:626-635 |
| ISSN: | 0022-2860 |
| DOI: | 10.1016/j.molstruc.2017.10.071 |
| Popis: | The bioactive 19-nor-clerodane trans-dehydrocrotonin (t-DCTN) is herein used as starting material to afford an epimeric derivative mixture so called t-DCTN-α and β-OL, which is a diastereoisomeric pair. The stereoselective reduction of t-DCTN was performed in methanol medium by using NaBH4 and CeCl3·7H2O which react reducing the C2 carbonyl group on the t-DCTN decalin ring moiety. The t-DCTN-diastereoisomeric compounds were characterized by chromatographic HPLC analyses and by NMR data. The crystal structure of t-DCTN-α-OL was confirmed employing X-ray diffraction. Additionally, an experimental and theoretical NMR chemical shifts study applied to the t-DCTN diastereoisomeric derivatives lead favorable coefficients of correlation (R > 0.98) by using B3LYP combined with 6–311++G(d,p) basis set. Furthermore, a modified Gemal and Luche's mechanism in stepwise fashion is proposed. Agreement between theoretical and experimental higher reactivity of NaBH4/Ce3+ towards NaBH4 was found and the theoretical results explicit the participation of the reaction solvent (methanol) on transition state by using NaBH4 unlike that involving NaBH4/Ce3+. It was found that the proposed modified mechanism only occurs in 0.8 eq. of Ce3+ salt. |
| Databáze: | OpenAIRE |
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