A convergent synthesis of the right-hand fragment of ciguatoxin CTX3C

A convergent synthesis of the right-hand fragment of ciguatoxin CTX3C was investigated. The first and second generation stereocontrolled syntheses of the LM ring fragment were achieved via spiroacetalization as a key step, respectively. The polyether framework of the HIJKLM ring fragment was constructed in a convergent manner by using intramolecular allylation, ring-closing metathesis, and stereoselective hydrogenation to form the 36-methyl substituent as the key transformations.