Studies on the neutral constituents of Pachysandra terminalis Sieb. et Zucc. Part IV. X-Ray structure of 3-O-acetyl-16-O-p-bromobenzoylpachysandiol B: new conformation of a friedelin-type triterpene
- 1 January 1975
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 2
- No. 6,p. 610-614
- https://doi.org/10.1039/p29750000610
Abstract
Crystals of the title compound (IVc) are orthorhombic, a= 15·58, b= 30·88, c= 7·40 Å, space group P212121, and Z= 4. The structure was solved from visually estimated three-dimensional X-ray data by the heavy-atom method, and refined by block-diagonal least-squares to R 14·3%(1722 independent reflections). A chair–chair–chair–boat–boat conformation of the five six-membered-ring skeleton was found, and it was confirmed that this and the quasi-all-chair are the stable conformations in friedelin-type triterpenes.Keywords
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