Total Synthesis of Bryostatin 16 - I

Bryostatins are class of macrolide lactones found in byrozoan. They exhibit anticancer activity and memory enhancement potency paving for its usage in Alzhemiers disease which generated lot of interest.Isolation from the byrozoan results in very low yields, warranting an efficient total synthesis. Only a few total synthesis of Bryostatins have been reported. Barry M. Trost and Guangbin Dong  has recently published their work on Bryostatin 16 in Nature
Click here to access the entire article. Nature 2008, 456, pp 485-488. DOI link :10.1038/nature07543.

Retrosynthesis


Keyplans

1. Gold catalyzed 6-endo dig cyclization leading to the formation of one (C) of the dihydropyran rings.

2. Macrocyclization using Pd catalysis to from a novel alkyne alkyne bond showing tremendous atom economy.

3. An elegant one pot cascade acid catalysis to fix another pyran ring (A).

4. Ruthenium catalyzed alkyne alkene bond formation to form one of the dihydropyran ring (B).