Direct oxidation of (-)-7α-triethylsiloxy-6β-triethylsiloxymethyl-3 -oxo-cis-2-oxabicyclo[3.3.0]octane with the Swern reagent proceeds selectively to afford (-)-7α-triethylsiloxy-6β-formyl-3-oxo-cis-2 -oxabicyclo[3.3.0]octane. Condensation of this aldehyde with dimethyl 2 -oxoheptylphosphonate under phase-transfer conditions gives (-)-7α -triethylsiloxy-3-oxo-6β-[3-oxo-1(E)-octenyl]-cis-2-oxabicyclo[3.3.0] octane which, on acidic hydrolysis, is converted into the known prostaglandine synthetic intermediate (-)-7α-hydroxy-3-oxo-6β-[3-oxo-1(E) -octenyl]-cis-2-oxabicyclo[3.3.0]octane.
(-)-7α-三乙基
硅氧基-6β-三乙基
硅氧基甲基-3-氧代顺-2-氧双环[3.3.0]
辛烷与斯温试剂的直接氧化选择性进行,生成(-)-7α-三乙基
硅氧基-6β-芳醛-3-氧代顺-2-氧双环[3.3.0]
辛烷。该醛与二甲基2-氧代庚基
磷酸酯在相转移条件下缩合,得到(-)-7α-三乙基
硅氧基-3-氧代-6β-[3-氧代-1(E)-
辛烯基]-顺-2-氧双环[3.3.0]
辛烷,该化合物在酸性
水解后转化为已知的
前列腺素合成中间体(-)-7α-羟基-3-氧代-6β-[3-氧代-1(E)-
辛烯基]-顺-2-氧双环[3.3.0]
辛烷。