Divergent Approach to Enmein-Type Natural Products

Key words

Diels–Alder reaction - Birch reduction - reductive alkenylation - ent-kaurenoids

Significance

Dong and co-workers have attained three highly oxygenated ent-kaurenoids from the isodon family of natural products by means of total synthesis. The significance of the work lies in the expeditious construction of key intermediate L, which was subsequently utilized as a common starting point in the preparation of (–)-sculponin R, (–)-isodocarpin, and (–)-enmein.

Comment

The authors commenced their synthetic route with the assembly of bicyclic ketone E by Diels–Alder cycloaddition. Birch reduction provided access to acetal G, which was subsequently transformed into enone I. In a single pot, Dong and co-workers constructed pivotal vinyl bromide L. Relying on reductive alkenylation strategies, this penta­cycle was used to access the three highlighted natural products.