Two concise enantioselective total syntheses of (-)-glabrescol implicate alternative biosynthetic pathways starting from squalene.

The C(2)-symmetric (-)-glabrescol was synthesized in two steps from (10S,11R)-dihydroxy-10,11-dihydrosqualene or squalene with 50% or 10% overall yields, respectively. These highly efficient and biomimetic syntheses employed a base-promoted middle-to-terminal double epoxide-opening cascade, which constructs the five tetrahydrofuran rings in glabrescol in one operation.