Expedient construction of the Ziegler intermediate useful for the synthesis of forskolin via consecutive rearrangements.

The Ziegler intermediate, useful for the total synthesis of forskolin, was synthesized in 10 reaction steps starting from commercially available alpha-ionone. This highly efficient synthesis relies on the success of two consecutive highly regio- and stereoselective rearrangements. The current synthesis has not only established an efficient synthetic route to access the Ziegler intermediate but it has also paved a way to the structural optimization of forskolin.