Synthesis of the BC/DE ring model of brevisin for confirmation of the structure around the acyclic junction

Total Synthesis of the Marine Ladder Polyether Gymnocin B

Herein, we report the first total synthesis of marine ladder polyether gymnocin B (1) based on a two-phase strategy. In Phase I, inspired by the proposed biosynthesis, epoxide-opening cascades assemble 10 out of 15 cyclic ether rings making up the molecular core. In the subsequent Phase II, coalescence elevates the molecular complexity further by coupling of these subunits. Our two-phase synthetic approach significantly improved the step efficiency of the synthesis of this class of natural products.

Rhodium-catalyzed endo-selective epoxide-opening cascades: formal synthesis of (-)-brevisin

[Rh(CO)2Cl]2 is as an effective catalyst for endo-selective cyclizations and cascades of epoxy-(E)-enoate alcohols, thus enabling the synthesis of oxepanes and oxepane-containing polyethers from di- and trisubstituted epoxides. Syntheses of the ABC and EF ring systems of (-)-brevisin via all endo-diepoxide-opening cascades using this method constitute a formal total synthesis and demonstrate the utility of this methodology in the context of the synthesis of marine ladder polyether natural products.

Total synthesis of (-)-brevisin: a concise synthesis of a new marine polycyclic ether

The first and highly efficient total synthesis of (-)-brevisin has been achieved. The title compound was synthesized in only 29 steps (longest linear sequence) from commercially available starting materials. The synthesis provided over 70 mg of a marine polycyclic ether compound.