Synthesis of ( )-Obtusenyne
SY Frankie Mak, Neil R Curtis, Andrew N Payne, Miles S Congreve, Andrew J Wildsmith, Craig L Francis, John E Davies, Sofia I Pascu, Jonathan W Burton, Andrew B Holmes
CHEMISTRY-A EUROPEAN JOURNAL | WILEY-V C H VERLAG GMBH | Published : 2008
An enantioselective synthesis of the halogenated medium-ring ether natural product (+)-obtusenyne is reported which uses the ring expansion of a seven-membered ketene acetal by means of a Claisen rearrangement to construct the core nine-membered oxygen heterocycle. The trans substituents across the ether linkage were established by using a transition-metal-catalyzed intramolecular hydrosilation reaction of an exo-cyclic enol ether. In addition, a formal synthesis of ent-obtusenyne from 2-deoxy-D-ribose is reported. A number of interesting points regarding the chemistry of medium-ring oxygen heterocycles are highlighted.