An Approach to the Carbon Backbone of Bielschowskysin, Part 1: Photocyclization Strategy

Several macrocyclization reaction attempts of highly advanced precursors toward a total synthesis of marine diterpene bielschowskysin are disclosed. Biomimetic [2+2]‐photocyclization reactions were applied to construct the cyclobutane core in these intermediates, which could be accessed along scalable high‐yielding reaction sequences from cheap enantiopure starting‐materials.