protection of threaded functions by the macrocycle, in this case promoting an unusual and disfavored 4-exo-trig ring closure. Kinetic and synthetic studies allowed us to delineate an advantageous approach toward β-lactams based on a two-step, one-pot protocol: an intramolecular ring closure followed by a thermally induced dethreading step. The advantages of carrying out this cyclization in the confined
描述了 N-
苄基富马
酰胺 [2] 轮烷的分子内环化。这些底物的机械键激活了这种转化,以高产率和区域选择性和非对映选择性方式进行,产生互锁的 3,4-二取代的 trans-azetidin-2-ones。这种激活效应明显不同于更常见的大循环对螺纹函数的屏蔽保护,在这种情况下,促进了一种不寻常且不受欢迎的 4-exo-trig 环闭合。动力学和合成研究使我们能够基于两步一锅法描绘出一种对 β-内
酰胺有利的方法:分子内闭环,然后是热诱导
脱螺纹步骤。在
苄基酰胺大环的密闭空间中进行这种环化的优势归因于它的嵌合辅助。