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Synfacts 2008(6): 0551-0551
DOI: 10.1055/s-2008-1072599
DOI: 10.1055/s-2008-1072599
Synthesis of Natural Products and Potential Drugs
© Georg Thieme Verlag Stuttgart · New York
Synthesis of Cassialoin
Contributor(s):Philip KocienskiY. Koyama, R. Yamaguchi, K. Suzuki*
Tokyo Institute of Technology, Japan
Total Synthesis and Structure Assignment of the Anthrone C-Glycoside Cassialoin
Angew. Chem. Int. Ed. 2008, 47: 1084-1087
Tokyo Institute of Technology, Japan
Total Synthesis and Structure Assignment of the Anthrone C-Glycoside Cassialoin
Angew. Chem. Int. Ed. 2008, 47: 1084-1087
Further Information
Publication History
Publication Date:
21 May 2008 (online)
Key words
cassialoin - cyclocondensation - nitrile oxides - benzoin condensation - thiazolium salts - C-glycosides
Significance
A significant development in the synthesis of cassialoin is the use of the a-ketol F as a selectively protected stereogenic anthrone surrogate in which the diastereotopic faces are differentiated thereby allowing control of the C-glycosidation reaction (F+G→H) at C10.
Comment
A regioisomer (17%) was formed in the cyclocondensation reaction of A and B. The a-ketol F was obtained as a single diastereoisomer. The epoxidation-reduction of glycal K (66%) installed the correct stereochemistry at C1¢ and C2¢.