The convergent total synthesis of furanocembranoids (FC) molestin E, ent-sinulacembranolide A and ent-sinumaximol A was achieved in 20–21 steps in the longest linear sequence (LLS). Building blocks were coupled through a furan metalation sequence and macrocycle formation was effected by Shiina lactonisation. The primary target molestin E was elaborated late-stage to 12 novel FC compounds.
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.Zum Volltext