Enantioselective synthesis of xanthatin.
The enantioselective synthesis of cytostatic and antibiotic xanthatin (1 a) is reported. As a key intermediate, a bicyclic compound 2 was identified, which can be readily synthesized from methyl-2-furoic acid in diastereo- and enantiomerically pure form. Compound 2 can be functionalized regio- and stereoselectively at C-6 and C-7, allowing the facile introduction of the functionalities found in xanthatin, as well as the synthesis of derivatives thereof. Moreover, a robust strategy for the introduction of the exo-methylene group at C-3, commonly found in many sesquiterpenes, was developed that makes use of masking the alkene in the α,β-unsaturated carbonyl system by O-pivaoyl, which is stable under acidic and mild basic conditions but eliminated upon treatment with strong bases.
Institut für Organische Chemie, Universität Regensburg, Universitätsstrasse 31, 93053 Regensburg (Germany), Fax: (+49) 941-943-4121.
Andreas
A
Bergmann
Oliver
O
Reiser
D005663:Furans / Q000138:chemical synthesis* / Q000737:chemistry*; D010084:Oxidation-Reduction; D013237:Stereoisomerism
D005663:Furans; C022186:xanthatin
allylic oxidation; exo-methylene group; synthetic methods; total synthesis; xanthanolides