Perfluoroalkyl-Substituted Thiophenes and Pyrroles from Donor–Acceptor Cyclopropanes and Heterocumulenes: Synthesis and Exploration of their Reactivity
作者:Daniel Gladow、Hans-Ulrich Reissig
DOI:10.1021/jo500534t
日期:2014.5.16
A methyl 2-trifluoromethyl-2-siloxycyclopropanecarboxylate was smoothly deprotonated by lithium diisopropylamide and reacted with carbon disulfide and methyl iodide to afford a dihydrothiophene derivative. The crucial step in this transformation is a ring-expansion of the anionic intermediate by [1,3] sigmatropic rearrangement. The dihydrothiophene was converted into the corresponding 5-trifluoromethylthiophene
用二异丙基氨基锂使2-三氟甲基-2-甲硅烷氧基环丙烷甲酸甲酯平滑地去质子化,并与二硫化碳和碘甲烷反应,得到二氢噻吩衍生物。此转变的关键步骤是通过[1,3]σ重排使阴离子中间体发生环扩环。在回流的吡啶中通过磷酰氯将二氢噻吩转化为相应的5-三氟甲基噻吩衍生物。一锅法式的反应顺序可高效提供噻吩,收率很高。类似地,芳基和烷基取代的异硫氰酸酯代替二硫化碳以中等至非常好的总产率提供了相应的三氟甲基取代的吡咯。