Chasing molecules that were never there: Adventures in natural product synthesis and structure elucidation

ORGN 295

Jonathan W. Burton, jonathan.burton@chem.ox.ac.uk1, Helen M. Sheldrake2, Craig Jamieson3, and Phillip A. Broadwith2. (1) Chemical Research Laboratories, Oxford University, 12 Mansfield Road, OX1 3TA Oxford, United Kingdom, (2) Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom, (3) Formerly at GlaxoSmithKline, Medical Research Centre, Stevenage, Herts SG1 2NY, United Kingdom
The structures of complex natural products are best confirmed by independent synthesis or X-ray crystallography. Advances in NMR spectroscopy over the previous twenty years have greatly improved the ease with which the structures of complex molecules are solved; however, in cases where crystallography is not possible, regio and stereo-controlled synthesis is still the best method for structure confirmation. In many cases through-heteroatom connectivity becomes a significant challenge in structure assignment using NMR spectroscopy especially in otherwise closely related molecules. The presentation will describe the total synthesis of two halogenated pyrano[3,2-b]pyrans which were the structures originally assigned to two marine natural products. The spectroscopic data for the synthetic material are inconsistent with the data reported for the natural products. Our re-assessment of the structures of the natural products will be reported.
 

Total Synthesis of Complex Molecules
1:00 PM-4:40 PM, Monday, March 26, 2007 McCormick Place East -- Room E352, Level 3, Oral

Division of Organic Chemistry

The 233rd ACS National Meeting, Chicago, IL, March 25-29, 2007