Roridin E and Baccharin

Still chose to establish the abolute stereochemistry at C-6 and C-13 by use of the chiral starting material, D-xylose (295). In seven steps this readily available sugar was transformed into the chiral ether (296) which represented a major portion of the macrocyclic chain. Selective attachment of the acid (296) to the primary hydroxyl group of verrucarol (82) proceeded smoothly and, following incorporation of the phosphonate (297), the diacyl verrucarol derivative (298) was obtained. Modification of the sugar nucleus followed by intramolecular condensation yielded the , Z-macrocycle (300) together wilth nearly equivalent amounts of the , -isomer (301). It is this advanced intermediate (300) which has served as a precursor to both roridin E (47) and baccharin B5 (59). 

Abrahamsson, S., and B. Nilsson The molecular structure of trichodermin. Acta Chem. Scand. 20, 1044 (1966). 

-----Direct determination of the molecular structure of trichodermin. Proc. Chem. Soc. 

Lowenbraun, B. Birch, R. Jarrell, and J. Garrard Anguidine a broad phase II study of the Southeastern Cancer Study Group. Cancer Treat. Rep. 68, 423 (1984). 

Anderson, W. K., and G. E. Lee Synthesis of C-ring-functionalized A-ring-aromatic trichothecane analogs. J. Organ. Chem. (USA) 45, 501 (1980). 

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