Cationic gold-catalyzed cycloisomerizations of propargylureas, derived in situ from secondary propargylamines and aryl or alkyl isocyanates, have been studied. The reaction outcome was found to be different from what was previously observed for the tosyl isocyanate-derived ureas in terms of both regio- and chemoselectivity. As a result, the current protocol offers efficient access to the 3,4-dihydropyrimidin-2(1H)-one core through the 6-endo-dig N-cyclization.
阳离子
金催化的
丙炔基
脲的环异构化反应已经研究,这些
脲是通过在位合成的次级
丙炔基胺和芳基或烷基
异氰酸酯获得的。研究发现,该反应的结果与之前观察到的来自托磺酰
异氰酸酯衍生的
脲在区位选择性和
化学选择性方面有所不同。因此,目前的方案通过6-内环-双N环化反应有效地获得了3,4-二氢
吡咯并-2(1H)-酮的核心结构。