合成路线1

The silylation of hydroxyester (XLVIII) with Tips-Cl and imidazole in THF gives the fully protected compound (XLIX), which is reduced with DIBAL in dichloromethane to the carbinol (L).The epoxidation of the double bond of (L) with MCPBA in dichloromethane yields the epoxide (LI), which is condensed with the Grignard reagent (LII) by means of CuI in ethyl ether/THF affording the diol (LIII). Esterification of the primary OH group of (LIII) with pivaloyl chloride gives the ester (LIV), which is desilylated with TBAF in THF providing the diol (LV). The cyclic ketalization of (LV) catalyzed by PdCl2 and benzoquinone yields the cyclic ketal (LVI), which is debenzylated as usual affording the primary alcohol (LVII). The oxidation of (LVII) with TPAP and NMO in dichloromethane gives the aldehyde (LVIII), which is condensed with diazophosphonate (XXVII) by means of K2CO3 in methanol yielding the ethynyl derivative (LIX), with simultaneous hydrolysis of the pivaloyl ester. The reaction of (LIX) with tributyltin hydride and PdCl2 in dichloromethane affords the vinyl stannane derivative (LX). Finally, the hydroxymethyl group of (LX) is oxidized with TPAP, NMO and NaClO2 to the corresponding carboxylic group of the desired tributylstannane intermediate (XXXII).