WestCHEM, School of Chemistry, The Joseph Black Building, University of Glasgow , Glasgow G12 8QQ, United Kingdom.
J Org Chem. 2016 Oct 21;81(20):9810-9819. doi: 10.1021/acs.joc.6b01881. Epub 2016 Oct 6.
A four-step synthesis of allylic trichloroacetimidates bearing a 2-proparyloxyaryl group has been developed from readily available 2-hydroxybenzaldehydes, and these have been used for the preparation of allylic amide derived 2H-chromenes using an Overman rearrangement and a 6-endo-dig hydroarylation. High yields of the 2H-chromenes were achieved using a stepwise approach involving an Overman rearrangement under thermal conditions followed by a hydroarylation reaction with a gold(I) triflimide catalyst. An alternative method where both reactions were performed as a one-pot process was also developed and instead used a gold(I) chloride catalyst activated by silver(I) hexafluoroantimonate for the cycloisomerization step. The allylic amide derived 2H-chromenes were converted to the corresponding coumarin analogues by a pyridinium dichromate (PDC)-mediated chemoselective allylic oxidation.
已开发出一种从易得的 2-羟基苯甲醛出发的带有 2-丙炔氧基芳基的烯丙基三氯乙酰胺的四步合成方法，并且这些烯丙基酰胺已用于使用 Overman 重排和 6-endo- dig 氢芳化反应制备烯丙基酰胺衍生的 2H-色烯。通过逐步方法实现了 2H-色烯的高产率，该方法包括在热条件下进行 Overman 重排，然后使用金（I）三氟甲磺酸酯催化剂进行氢芳化反应。还开发了一种替代方法，其中两个反应都作为一锅法进行，而是使用银（I）六氟锑酸盐激活的金（I）氯化物催化剂用于环异构化步骤。烯丙基酰胺衍生的 2H-色烯通过吡啶二铬（PDC）介导的选择性烯丙基氧化转化为相应的香豆素类似物。
