合成路线1

Oxetanone (XLV) can also be obtained as follows: The reaction of 3(R)-hydroxytetradecanoic acid tert-butyl ester (XLVI) with DHP and p-toluenesulfonic acid gives the corresponding tetrahydropyranyl ether (XLVII), which is reduced with dibutylaluminum hydride (DIBAL) in toluene to the aldehyde (XI), already obtained. Compound (XI) is condensed with 2-(p-toluenesulfinyl)acetic acid tert-butyl ester (XLVIII) by means of tert-butylmagnesium bromide in ether-THF affording the sulfinylhydroxy ester (II), which is treated with aluminum amalgam in THF-water to yield the hydroxy ester (L). The alkylation of (L) with hexyl bromide (LI) by means of butyllithium and diisopropylamine in THF-hexane affords 2-hexyl-3(S)-hydroxy-5(R)-(tetrahydropyranyloxy)hexadecanoic acid tert-butyl ester (LII), which is hydrolyzed with KOH in methanol to the corresponding free acid (LIII). The lactonization of (LIII) with pyridinium p-toluenesulfonate in hot ethanol affords oxetanone (LIV) as a diastereomeric mixture, which is separated by column chromatography, finally yielding oxetanone (XLV), previously obtained in scheme 11082301c.