Laurencia natural products. Part I. Crystal structure and absolute stereochemistry of laurencin
- 1 January 1969
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society B: Physical Organic
- p. 559-564
- https://doi.org/10.1039/j29690000559
Abstract
The crystal structure and the absolute stereochemistry of laurencin have been determined by a single-crystal X-ray analysis. The crystals are orthorhombic, space group P212121 with four molecules of C17H23O3Br in a unit cell of dimensions a= 7·70, b= 9·70, c= 22·93 Å. The structure was solved by the heavy-atom method and refined by least-squares calculations. R is 0·103 for 1152 reflexions. The absolute stereochemistry was determined by consideration of anomalous dispersion effects. The molecule is unusual in that it has an eight-membered ether-ring containing a cis-double bond. Laurencin provides an example of strong intermolecular–C⋮CH ⋯ O hydrogen-bonding in the solid state as revealed by i.r. absorption data. In the crystal, the terminal ethynyl group of a trans-hex-3-ene-5-yne side-chain is involved in a bifurcated hydrogen bond with ether and acetate oxygen atoms of a neighbouring molecule.Keywords
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