合成路线1

The oxetanone (XXIII) can also be obtained as follows: The condensation of 3(R)-benzyloxytetradecanal (XI) with octanoic acid (XXXIV) by means of lithium diisopropylamide gives 5(R)-benzyloxy-2-hexyl-3-hydroxyhexadecanoic acid (XXXV), which is deprotected by hydrogenation with H2 over Pd/C yielding the dihydroxy acid (XXXVI). The lactonization of (XXXVI) with p-toluenesulfonic acid affords the hydroxy lactone (XXXVII), which is oxidized with CrO3 H2SO4 to 3-hexyl-6(R)-undecyltetrahydropyran-2,4-dione (XXXVIII). Hydrogenation of (XXXVIII) with H2 over PtO2/C in ethylacetate gives (3S,4S,6R)-3-hexyl-4-hydroxy-6-undecyltetrahydropyran-2-one (XXXIX), which is benzylated with benzyl trichloroacetimidate to the 4-benzyloxy derivative (XL). Ring opening of (XL) with KOH in dioxane-water yields the hydroxy acid (XLI), which is esterified with benzyl bromide to the benzyl ester (XLII). The reaction of (XLII) with dihydropyran (DHP) by means of p-toluenesulfonic acid in dichloromethane affords (2S,3S,5R)-3-benzyloxy-2-hexyl-5-(tetrahydropyran-2-yloxy)hexadecanoic acid benzyl ester (XLIII), which is debenzylated by hydrogenation with H2 over Pd/C in THF to the hydroxy acid (XLIV). The cyclization of (XLIV) with p-toluenesulfonyl chloride in pyridine gives (3S,4S)-3-hexyl-4-[2(R)-(tetrahydropyran-2-yloxy)tridecyl]oxetan-2-one (XLV), which is finally deprotected with pyridinium p-toluenesulfonate in ethanol to afford the oxetanone (XXIII), already obtained in scheme 11082301a.