Stereochemistry Determination by Powder X-ray Diffraction Analysis and NMR Residual Dipolar Couplings

MANUELA E. GARCÍA; SILVINA PAGOLA; ARMANDO NAVARRO-VÁZQUEZ; DAMILOLA D. PHILLIPS; CHAKICHERLA GAYATHRI; HENRY KRAKAUER; PETER W. STEPHENS; VIVIANA E. NICOTRA; ROBERTO R. GIL

ANGEWANDTE CHEMIE

VCH PUBLISHERS INC

Lugar: Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim; Año: 2009 vol. 121 p. 5780 - 5784

0570-0833

Traditional techniques for stereochemistry analysis have limitations; for example solution NMR spectroscopy has spatial limitation for the transference of stereochemical information, and suitable single crystals for X-ray analysis may not be available. Residual dipolar coupling (RDC) and powder X-ray diffraction (PXRD) are both techniques whose use is not yet widespread. We report a double-blind solution of the structure of jaborosalactol 24 (1), a new withanolide isolated from Jaborosa parviflora (Phil.) A. T. Hunziker et Barboza, by RDCs and PXRD, since conventional NMR spectroscopy experiments such as nuclear Overhauser effect (NOE) and 3 J analysis did not provide a unique solution.