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本文报道了三氟丁-[2]-炔酸乙酯(2a)和七氟己-[2]炔酸乙酯(2b)的合成。产物在水溶液中用氢氧化钠皂化,和相应的甲酯一样,也发生特殊的炔酯-烯醚重排,乙氧基迁移到β碳上,酸化后,分别得到3-乙氧基-4,4,4-三氟丁-[2]-烯酸(3a)和3-乙氧基-4,4,5,5,6,6,6-七氟己-[2]-烯酸(3b)。其结构经元素分析,红外吸收光谱和核磁共振谱证明。文中还研究了炔酯-烯醚重排反应的立体化学。根据重排产物的~1H NMR数据,确定重排是高度立体选择性的,所有产物中Z异构体占94％以上。根据构象分析,得到合理的解释。NMR的溶剂效应和NOE增强,也进一步确证了重排产物的构型。
This paper reports the synthesis of trifluorobutyl- [2] -ynoic acid ethyl ester (2a) and heptafluorohexyl- [2] alkynoate (2b). The product was saponified with sodium hydroxide in aqueous solution. Like the corresponding methyl ester, a special acetylenic ester-enolis rearrangement occurred. The ethoxy group was translocated onto β-carbon and acidified to give 3-ethoxy-4 Trifluoro-2- [2] -enoic acid (3a) and 3-ethoxy-4,4,5,5,6,6,6- heptafluorohexyl- [2] -enoic acid 3b). Its structure was confirmed by elemental analysis, infrared absorption spectrum and nuclear magnetic resonance spectrum. The stereochemistry of acetylenic ester-enolis rearrangement reaction has also been studied. Based on the ~ 1H NMR data of the rearranged products, it was confirmed that rearrangement was highly stereoselective with Z isomers in all products accounting for more than 94%. According to the conformational analysis, get a reasonable explanation. The solvent effect of NMR and NOE enhancement further confirmed the configuration of rearranged products.