A Concise Approach to Enantioselective Synthesis of Euolutchuols A, B, and D and Their Structure Assignment

We demonstrated the first enantioselective total syntheses
and
structural assignment of euolutchuols A, B, and D. The syntheses begin
with a biomimetic cationic polyene cyclization of epoxy-polyene, yielding
the natural product β-hydroxy-8,11,13,15-abietatetraene, which
serves as the starting material for all euolutchuols. Two alternative
methods, enantioselective copper-catalyzed hydroboration and oxidation,
as well as Sharpless dihydroxylation and reductive deoxygenation,
were employed to construct the 15-methyl stereogenic center, and stereochemistry
is established by X-ray analysis. Selective synthetic methods are
employed to install 12-hydroxy and 2-oxo groups to produce euolutchuols
B and D.