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.