合成路线1

The hydrolysis of the mesylate group of (XXVI) with NaOH in refluxing MeOH/water, followed by reaction with Ac2O and pyridine gives the diacetate (XXVII). The cleavage of the Boc group of (XXVII) by means of TFA in dichloromethane, followed by reprotection with Troc-Cl and NaHCO3 in dichloromethane yields the expected compound (XXVIII). The reaction of (XXVIII) with dimethyldioxirane and CSA in MeOH/acetone affords the acid-sensitive epoxide (XXIX), which, without isolation, is treated with MeOH and CSA to provide the methoxy alcohol (XXX). The reduction of (XXX) with NaBH3CN and TFA provides the chiral alcohol (XXXI) as a single isomer, which is protected with Tbdms-Cl and imidazole to give the silyl ether (XXXII). Cleavage of the Ac groups of (XXXII) by means of guanidinium nitrate and NaOMe in methanol/dichloromethane yields the dihydroxy compound (XXXIII).