Synthesis of prelaureatin, laurencin, and the medium-ring ether parts of ciguatoxins

Abstract

If a ring-closing olefin metathesis (RCM) reaction is employed for the synthesis of a naturally occurring medium-ring ether, stereoselective construction of the acyclic di-sec-alkyl ether part of the RCM precursors is a problem. Therefore, we have developed a process including C-glycosidation of a hexopyranose and ring-cleavage of the resulting C-glycoside as a solution for the problem. In fact, the combined use of the C-glycoside-cleavage process and RCM was very effective for the synthesis of the medium-ring ether parts of ciguatoxins, the principal causative toxins of ciguatera seafood poisoning, as well as for the total synthesis of prelaureatin and laurencin, which originated from Laurencia red alga.