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Novel Stereocontrolled Approach to syn‐ and anti‐ Oxepene–Cyclogeranyl trans ‐Fused Polycyclic Systems: Asymmetric Total Synthesis of (−)‐Aplysistatin, (+)‐Palisadin A, (+)‐Palisadin B, (+)‐12‐Hydroxy‐Palisadin B, and the AB Ring System of Adociasulfate‐2 and Toxicol A
Author(s) -
Couladouros Elias A.,
Vidali Veroniki P.
Publication year - 2004
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200400407
Subject(s) - chemistry , epoxide , stereochemistry , stereoselectivity , ring (chemistry) , metathesis , ring closing metathesis , total synthesis , enantioselective synthesis , cis–trans isomerism , catalysis , organic chemistry , polymerization , polymer
A new stereocontrolled method for the formation of trans‐anti cyclogeranyl–oxepene systems is described. The demanding stereochemistry is secured by stereoselective coupling of a cyclogeranyl tertiary alcohol with a 1,2‐unsymmetrically substituted epoxide, while the formation of the highly strained oxepene is achieved employing ring‐closing metathesis. Since the stereochemistry of the trans ‐fused 6,7‐ring system is determined by the epoxide, the method also allows the construction of trans–syn 6,7‐ring systems. This approach leads to the synthesis of the AB fragment of Adociasulfate‐2 and Toxicol A, for the first time. The flexibility and efficiency of the presented strategy is demonstrated by the total asymmetric synthesis of (−)‐Aplysistatin, (+)‐Palisadin A, (+)‐12‐hydroxy‐Palisadin B, and (+)‐Palisadin B, employing two similar key intermediates.