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Progress in the Synthesis of the Lituarines:  Stereocontrol in Sequential C−C Bond Formation on a Spirobutenolide Template

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journal contribution
posted on 27.10.2005, 00:00 by Jeremy Robertson, Jonathan W. P. Dallimore
We describe elaboration of a tricyclic spirobutenolide corresponding to the C(7−18) tricyclic substructure common to lituarines A−C. Conjugate addition, to install the C(16) methyl, is followed by construction of the crucial C(18−19) bond by silyl enol ether addition to the derived spiroacetal C(18)−O oxonium ion. Esterification with a C(1−6) acid, and selective ozonolysis to release the C(23) carbonyl, complete the assembly of all the carbons present in the lituarine macrocyclic core.