合成路线1

Synthesis of intermediate (XLIII): The condensation of dithiane intermediate (VII) with epoxide intermediate (XIV) by means of NaOtBu and n-BuLi gives alcohol (XXXIV), which is converted into epoxide (XXXV) by treatment with pyridinium p-toluenesulfonate (PPTS), NaH and tosyl-imidazole in THF. The condensation of (XXXV) with intermediate iodovinyl compound (XX) by means of n-BuLi in THF yields the diol (XXXVI), which is treated with CaCO3 and NIS to afford the spiroketal (XXXVII). The monoacylation of (XXXVIII) with methoxyacetyl chloride (XXXVIII) and LiNH2, followed by cleavage of the cyclohexylidene ketal with PPTS, provides the triol (XXXIX), which is selectively silylated at the primary OH group with TBDMSCl to give the silyl ether (LX). The acylation of the two secondary OH groups of (LX) with Ac2O and DMAP yields the diacetate (XLI), which is desilylated with HF and pyridine in acetonitrile afford the primary alcohol (XLII). Finally, this compound is oxidized with DMP in dichloromethane to furnish the desired intermediate aldehyde (XLIII).