Convergent synthesis of the IJKLM-ring part of ciguatoxin CTX3C

Convergent Synthesis of the Right-Hand Segment of Ciguatoxin

“…The vinyl triflate was cross-coupled with methylmagnesium bromide in the presence of Fe(acac) 3 , affording the endo -olefin 19 in good yield . The endo -olefin was hydrogenated stereoselectively using Crabtree's catalyst to give a single diastereoisomer . We could not determine the stereochemistry of the C(39) position in this step.…”

Marine natural products: synthetic aspects

“…Fujiwara and co-workers have detailed a convergent synthesis of the IJKLM-ring system 48 of ciguatoxin CTX3C (Scheme 10). 46 This was achieved by first joining the I-ring fragment 49 to the L-ring fragment 50, then forming the K-ring using a reductive cyclization protocol. Alkylation of the dimethyldithioacetal 49 with 0.19 equivalents of the aldehyde 50 47 produced a mixture of diastereomers, which were deprotected under acidic conditions.…”