Total Synthesis of Berkeleyone A and Preaustinoid A through Epoxypolyene Cyclization

A bioinspired Lewis acid-catalyzed epoxypolyene cyclization was developed to construct the tetracyclic framework containing a bicyclo[3.3.1]nonane core and seven chiral centers. The usage of this approach for assembling these natural products of 6/6/6/6 tetracyclic skeleton with bicyclo[3.3.1]nonane core is demonstrated by the total synthesis of highly oxidized berkeleyone A and preaustinoid A.