Further Withaphysalin Derivatives from Acnistus arborescens |
| |
| Authors: | Ana Isabel V. Maia Raimundo Braz‐Filho Edilberto R. Silveira Carlos Alberto de Simone Otília Deusdênia L. Pessoa |
| |
| Affiliation: | 1. Departamento de Química Organica e Inorganica, Centro de Ciências, Universidade Federal do Ceará, CP 12.200, 60021‐940, Fortaleza‐CE, Brazil;2. Departamento de Física e Informática, Instituto de Física, Universidade de S?o Paulo, CP 369, CEP 13566‐970, S?o Carlos‐SP, Brazil |
| |
| Abstract: | Two new epimeric chlorinated withaphysalins, rel‐(4β,5β,6α,18S,22R)‐ and rel‐(4β,5β,6α,18R,22R)‐6‐chloro‐18,20‐epoxy‐18‐ethoxy‐4,5‐dihydroxy‐1‐oxowitha‐2,24‐diene‐26,22‐lactone ( 1 and 2 resp.), together with the new rel‐(4β,5β,6α,18R,22R)‐6‐chloro‐18,20‐epoxy‐4,5‐dihydroxy‐18‐methoxy‐1‐oxowitha‐2,24‐diene‐26,22‐lactone ( 3 ) and rel‐(3β,4β,5β,6β,18R,22R)‐5,6:18,20‐diepoxy‐3,18‐diethoxy‐4‐hydroxy‐1‐oxowith‐24‐ene‐26,22‐lactone ( 4 ) were isolated from the leaves of Acnistus arborescens and named withaphysalins T–W, respectively. The final structures and the complete 1H‐ and 13C‐NMR assignments of the three chlorowithaphysalins 1 – 3 were performed by means of HR‐ESI‐MS and 1D‐ and 2D‐NMR experiments, including COSY, HSQC, and HMBC, beside comparison with spectral data of analogous compounds from the literature. The structure of 4 was also confirmed by means of a single‐crystal X‐ray diffraction analysis. |
| |
| Keywords: | Acnistus arborescens Withaphysalins T – W Withasteroids Chlorowithaphysalins |
|
|
