Enantioselective Total Synthesis of -Amphidinolide

In fact, the sensitive disubstituted alkene of 14 turned out to not be stable to the subsequent AlCl, coupling conditions, so the alkene and the secondary alcohol were protected together as the bromoether 15. Condensation of the derived enol ether 16 with the sulfone 2 in the presence of DTBMP (2,6-di-r-butyl-4-methylpyridine) then gave 17. Yamaguchi lactonization followed by regeneration of the alkene by zinc reduction completed the synthesis of 1. 

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In Ghosh s enantioselective total synthesis of the cytotoxic marine macrolide (+)-amphidinolide T1 (318) [143], the C1-C10 fragment 317 was constructed by CM of subunits 315 and 316 (Scheme 62). The reaction mediated by catalyst C (5 mol%) afforded in the first cycle an inconsequential 1 1 mixture of (E/Z)-isomeric CM products 317 in 60% yield, along with the homodimers of 315 and 316. The self-coupling products were separated by chromatography and exposed to a second metathesis reaction to provide olefins 317 in additional 36% yield [144]. 

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