A Kinetic Dearomatization Strategy for an Expedient Biomimetic Route to the Bielschowskysin Skeleton

A Vicinal Diol Approach for the Total Synthesis of Molestin E, ent-Sinulacembranolide A and ent-Sinumaximol A

In this work an approach for the synthesis of furanocembranoid natural products containing the C-7,8-diol moiety is disclosed. This culminated in the first total synthesis of the natural product molestin E, together with ent-sinulacembranolide A and ent-sinumaximol A as well as a thorough exploration of their chemistry. Late-stage ring-closure of the C-7,8-diols to the corresponding epoxides was also demonstrated. Key features of this synthetic strategy include a stereoselective Baylis-Hillman reaction, ring-closing metathesis and Shiina macrolactonisation. Chiral-pool materials were deployed to ensure the desired absolute stereochemistry which was confirmed by late-stage single crystal X-ray diffraction.

An Unexpected Transannular [4+2] Cycloaddition during the Total Synthesis of (+)-Norcembrene 5

We report a concise and versatile total synthesis of the diterpenoid (+)-norcembrene 5 from simple building blocks. Ring-closing metathesis and an auxiliary-directed 1,4-addition are the key steps of our synthetic route. During the synthesis, an unprecedented, highly oxidized pentacyclic structural motif was established from a furanocembranoid through transannular [4+2] cycloaddition.