A Bioinspired Cyclization Sequence Enables the Asymmetric Total Synthesis of Dictyoxetane

摘要

We have developed the first synthesis of the unique oxetane containing diterpene (+)-dictyoxetane. Our retrosynthetic planning was guided by the putative biosynthesis of the unprecedented 2,7-dioxatricyclo-[4.2.1.0~(3,8)]nonane ring system. A bioinspired 4-exo-tet, 5-exo-trig cydization sequence enabled the construction of the synthetically challenging dioxatricyclic framework. The overall synthesis proceeds in 15 linear steps from a known and readily available trans-hydrindane fragment. In addition, we were able to realize the first dyotropic rearrangement of an epoxide-oxetane substrate.