合成路线1

The condensation of propane-1,3-diol (XXV) with benzaldehyde by means of p-toluenesulfonic acid gives the corresponding cyclic acetal (XXVI), which is reduced with diisobutylaluminum hydride in toluene yielding 3-benzoyloxy-1-propanol (XXVII). The oxidation of (XXVII) with oxalyl chloride as before affords the corresponding aldehyde (XXVIII), which is submitted to a Wittig condensation with 2-(triphenylphosphoranylidene)acetic acid methyl ester (XXIX) giving (E)-5-benzyloxy-2-pentenoic acid methyl ester (XXX). The hydrolysis of (XXX) with NaOH in THF-water yields the corresponding acid (XXXI), which is condensed with pivaloyl chloride (XXXII) to afford the mixed anhydride (XXXIII). The condensation of (XXXIII) with 4(S)-benzyloxazolidin-2-one (XXXIV) by means of BuLi in THF gives 4(S)-benzyl-3-[5-benzyloxy-2(E)-pentenoyl]oxazolidin-2-one (XXXV), which is submitted to a Diels-Alder cycloaddition with cyclopentadiene (XXXVI) to yield 4-benzyl-3-[(3R,4R,5S,6S)-5-(2-benzyloxyethyl)bicyclo[2.2.1]hept-2-en-4-ylcarbonyl]oxazolidin-2-one (XXXVII). Hydrogenation of (XXXVII) with H2 over Pt in ethylacetate, followed by hydrolysis with H2O2 and LiOH affords (1R,2R,3S,4S)-3-(2-benzyloxyethyl)bicyclo[2.2.1]heptane-2-carboxylic acid (XXXVIII). The formation of the corresponding azide with ethyl chloroformate and sodium azide followed by degradation in refluxing toluene gives the amine (XXXIX), which is acylated with benzenesulfonyl chloride as before yielding the sulfonamide (XL). The deprotection of (XL) by hydrogenolysis with H2 over Pd/C in ethanol affords the substituted ethanol (XLI). Oxidation of (XLI) with oxalyl chloride as before gives the aldehyde (XLII), which is finally submitted to a Wittig condensation with 4-carboxybutyl triphenylphosphonium bromide and t-BuOK to yield acid (XIV) enantiomerically pure, already obtained.