合成路线1

The condensation of the chiral octahydroquinoline (I) with phenyl(phenylsulfanylmethyl)sulfone by means of BuLi in THF gives the perhydroquinoline adduct (II), which is treated with Bu3SnH and AIBN in refluxing benzene to yield the phenylsulfonylmethyl derivative (III). The reduction of the ketonic group of (III) with NaBH4, followed by elimination of the resulting OH group by reaction with thiocarbonyldiimidazole and then with Bu3SnH in refluxing benzene affords the chiral perhydroquinoline-1-carboxylic acid methyl ester derivative (IV). Decarboxylation of (IV) by means of Pr-S-Li in THF/HMPA, followed by reprotection with Boc2O in refluxing benzene provides the chiral tert-butyl carbamate (V), which is condensed with trans-2-heptenal by means of BuLi in THF and then treated with Na/Hg in methanol to give the 5-(1,3-octadienyl) derivative (VI). Finally compound (VI) is decarboxylated by means of HCl in refluxing methanol o afford the target lepadin B.