A Concise Catalytic Route to the Marine Sesquiterpenoids (-)-Clavukerin A and (-)-Isoclavukerin A
作者:Stephan Knüppel、Victor O. Rogachev、Peter Metz
DOI:10.1002/ejoc.201001087
日期:2010.11
zed strategy, the enantiopure title hydroazulenes were prepared in only four steps from (S)- and (R)-citronellal, respectively. A catalyst-controlled diastereoselective Michael addition of these aldehydes to methyl vinyl ketone followed by chemoselective dibromoolefination and one-pot Wittig olefination/alkyne formation afforded the key dienynes that underwent regioselective domino metathesis to yield
Relay metathesis enabled an improved access from (S)-citronellal to the marine trisnorguaiane (−)-clavukerin A. This hydroazulene was applied as an advantageously functionalized building block for the asymmetric synthesis of the sesquiterpene lactone osmitopsin and the proposed structure of 4,5-epoxyosmitopsin using a chemo-, regio-, and diastereoselective diepoxide opening as the key step.