Department of Chemistry, Middle East Technical University, 06800 Ankara, Turkey.
Org Biomol Chem. 2019 Feb 27;17(9):2529-2541. doi: 10.1039/c8ob03180k.
A new method for the synthesis of 2,4,5-trisubstituted pyridines from N-propargylic β-enaminothiones is reported. β-Enaminothiones were prepared by thionation of the corresponding β-enaminones with Lawesson's reagent. When treated with diisopropylamine in DMF at room temperature, N-propargylic β-enaminothiones yielded 2,4,5-trisubstituted pyridines in moderate to high yields, along with small amounts of 2-methylene-2,3-dihydro-1,4-thiazepines. The reaction was found to be general for a broad range of N-propargylic β-enaminothiones and tolerated the presence of aromatic, heteroaromatic and aliphatic groups with electron-withdrawing and electron-donating substituents. The method could be widened to the internal alkyne-tethered N-propargylic β-enaminothiones. This operationally simple method may provide rapid access to a library of functionalized pyridines of pharmacological interest.
报道了一种从 N-丙炔基β-烯胺硫酮合成 2,4,5-三取代吡啶的新方法。β-烯胺硫酮是通过劳森试剂对相应的β-烯胺酮进行硫代反应制备的。当 N-丙炔基β-烯胺硫酮在室温下用二异丙胺处理时，在 DMF 中以中等至高产率得到 2,4,5-三取代吡啶，同时还得到少量 2-亚甲基-2,3-二氢-1,4-噻嗪。该反应对广泛的 N-丙炔基β-烯胺硫酮具有普遍性，并且可以容忍具有吸电子和供电子取代基的芳族、杂芳族和脂肪族基团的存在。该方法可以扩展到内部炔烃键合的 N-丙炔基β-烯胺硫酮。这种操作简单的方法可能为具有药理学意义的功能化吡啶文库提供快速通道。
