Palladium-Catalyzed Intramolecular Allylic Alkylation Reaction in Marine Natural Product Synthesis: Enantioselective Synthesis of (+)-Methyl Pederate, a Key Intermediate in Syntheses of Mycalamides.

ABSTRACT

A novel preparation of (+)-methyl pederate (4), a key intermediate in syntheses of mycalamides (1), marine natural products from a New Zealand sponge of the genus Mycale, is described. The key step involves palladium-catalyzed intramolecular allylic alkylation of the carbonate 21, derived from (+)-(4R,5R,E)-5-(tert-butyldimethylsiloxy)-4-methyl-2-hexenol (13), yielding lactones 5 in 87% yield. Demethoxycarbonylation of the cyclization products 5 and further functional group transformations led to (+)-methyl pederate (4).