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Stereoselective Synthesis of C ‐2‐Methylene and C ‐2‐Methyl α‐ and β‐ C ‐Glycosides from 2‐ C ‐Branched Glycals: Formal Total Synthesis of (–)‐Brevisamide
Author(s) -
Sudharani Chalapala,
Venukumar Patteti,
Sridhar Perali Ramu
Publication year - 2014
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201403062
Subject(s) - chemistry , stereoselectivity , methylene , glycoside , stereochemistry , claisen rearrangement , total synthesis , organic chemistry , catalysis
The stereoselective synthesis of deoxy C ‐glycoside derivatives that have a methylene or methyl group at C ‐2 position was investigated by employing the Claisen rearrangement of 2‐vinyloxy methyldeoxy‐glycals as the synthetic precursors. The method proceeded with high diastereoselectivity to afford C ‐2‐methylene α‐ C ‐glycosides. Complementary to this protocol, a Zn II ‐mediated anomerization of the α‐ C ‐glycosides to give the corresponding β‐ C ‐glycosides was also used to obtain diastereomerically pure C ‐2‐methylene β‐ C ‐glycosides. The generality of the reaction was fully evaluated, and the developed method was successfully applied to the formal stereoselective total synthesis of (–)‐brevisamide, a monocyclic ether alkaloid that was isolated from Karenia brevis (red tide dinoflagellate).