Photochemical and Thermal [2 + 2]-Cycloaddition to Generate the Bicyclo[3.2.0]heptane Core of Bielschowskysin

Farcet, Jean-Baptiste; Himmelbauer, Martin; Mulzer, Johann

Eur. J. Org. Chem. 2013, 4379-4398.

A bicyclic core fragment of the marine diterpenoid bielschowskysin has been synthesized. First, a large library of precursors for a photochemical [2 + 2] cycloaddition was prepared and tested, but with limited success. In the end, a thermal [2 + 2] cycloaddition followed by appropriate regio- and stereocontrolled functionalization efficiently gave access to the desired bicyclo[3.2.0]heptane core. An optimized route to this remarkable molecular structure is presented.