Total Synthesis of (-)-Colombiasin and (-)-Elisapterosin B

doi:10.1055/s-2005-865343

Synfacts 2005(0): 0003-0003
DOI: 10.1055/s-2005-865343

Synthesis of Natural Products and Drugs

Total Synthesis of (-)-Colombiasin and
(-)-Elisapterosin B

Contributor(s): Philip Kocienski

D. C. Harrowven*, D. D. Pascoe, D. Demurtas, H. O. Bourne
Southampton University, UK
Total Synthesis of (-)-Colombiasin A and (-)-Elisapterosin B
Angew. Chem. Int. Ed. 2005, 44: 1221-1222

Abstract

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Key words

[4+2] cycloaddition - [5+2] cycloaddition - diterpenes - Moore rearrangement

Significance

The target molecules were isolated from the gorgonian octocoral Pseudopterogorgia elisabethae. Elisapterosin B is active against Plasmodium falciparum, the parasite associated with malaria. Two of the three stereogenic centers in D were derived from (-)-dihydrocarvone; the third was generated by hydroboration with Ipc₂BH. All remaining stereogenic centers were created by substrate-controlled processes.

Comment

A very economical synthesis of the target molecules was achieved using a sequence of pericyclic reactions. Hydroquinone D, generated by a Moore rearrangement of the cyclobutenone A, underwent a thermal [4+2] cycloaddition to give Colombiasin A and a Lewis-acid-catalyzed [5+2] cycloaddition on treatment with BF₃·OEt₂ to give Elisapterosin B.

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