Total Synthesis of Gymnocin B
Total Synthesis of the Marine Ladder Polyether Gymnocin B.
J. Am. Chem. Soc. 2019;
17. September 2019 (online)
Sittihan and Jamison report the total synthesis of gymnocin B, the second largest contiguous marine ladder polyether isolated to date. This complex target features 15 cyclic ether rings and 33 stereogenic centers, posing an exceptional synthetic challenge. The authors succeeded in the preparation of gymnocin B by implementation of bioinspired epoxide-opening cascades and a series of fragment couplings and cyclizations.
Key components D, E, and F were prepared from easily accessible compounds by exquisitely controlled epoxide-opening cascades. Further elaboration of these building blocks allowed combination of subunits G–J and construction of the remaining rings to afford the exceedingly challenging target gymnocin B.