Progress Towards the Total Synthesis of Lancifodilactone G
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Date
2007-06
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The Ohio State University
Abstract
Lancifodilactone G is a member of a unique set of eight ring systems that expresses anti-HIV, anti-tumor, and anti-hepatitis activities. A pathway has been proposed to synthesize the two halves of this complicated molecule with the hope of joining them to make the natural product.
The synthesis of the eastern sector of the molecule has been focused on the formation of a five-membered lactone 8. This will serve as the base of the D and H rings of the system. The rings will be formed by two separate fragments 9 and 11. Completion of the proposed synthesis will also lead to the discovery and characterization of new compounds. Fragment 9 has been nearly accomplished through seven steps of a nine step path, but the yield dropped with the hydrogenolysis to cleave a benzyl protecting group. Fragment 11 has progressed through two steps of a six step synthesis, as it proved difficult to work with the unstable 4-methoxybenzyl chloride to protect an alcohol.
Concerning the western sector of the molecule, we have been working on a model study of the deoxygenation of a highly functionalized enone 46. The synthesis of this sector has advanced 22 steps along the pathway, but there is no current documentation on the removal of a carbonyl oxygen that is compatible with the acid sensitive acetal functionality present in our molecule. Completion of the western sector should follow the discovery of a new method. We have currently completed the first three optimized steps of a six step synthesis. The completed three steps have introduced unknown compounds high yields that have enlisted further characterization.
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Keywords
synthesis, anti-HIV