Mechanoresponsive Carbamoyloximes for the Activation of Secondary Amines in Polymers.
Mechanoresponsive Carbamoyloximes for the Activation of Secondary Amines in Polymers.
复制标题
DOI：
10.1002/anie.202207557
复制
发表时间：
2022-09-26
期刊：
影响因子：
--
通讯作者：
中科院分区：
文献类型：
--
作者：
机械载体是结合到聚合物中的分子部分，通过结构、构型或构象键重排来响应力以实现功能。到目前为止，一些化学潜伏基序已经被聚合物机械化学方法激活，但仲胺的产生仍然难以捉摸。本文报道了氨甲酰肟作为仲胺的机械化学保护基团。我们发现氨甲酰肟在聚合物的N - O肟键上发生力诱导的均解键断裂，从而产生游离胺，因为反应通过氨甲酰氧基和胺基自由基进行，类似于光化学对应物。最后，我们将氨甲酰肟基序应用于力激活的有机催化Knoevenagel反应。我们相信这种保护策略可以普遍应用于高分子材料中的许多其他仲胺和伯胺。当嵌入到聚合物中时，氨甲酰醛肟会发生肟N - O键的机械化学均解键断裂。随后的自由基反应机制主要是通过氢解离生成腈，通过脱羧和抽氢生成游离胺。力诱导的有机催化被证明是对仲胺的激活。
Mechanophores are molecular moieties that are incorporated into polymers and respond to force with constitutional, configurational, or conformational bond rearrangements to enable functionality. Up to today, several chemically latent motifs have been activated by polymer mechanochemical methods, but the generation of secondary amines remains elusive. Here we report carbamoyloximes as mechanochemical protecting groups for secondary amines. We show that carbamoyloximes undergo force‐induced homolytic bond scission at the N−O oxime bond in polymers thus producing the free amine, as the reaction proceeds via the carbamoyloxyl and aminyl radicals, analogously to its photochemical counterpart. Eventually, we apply the carbamoyloxime motif in a force‐activated organocatalytic Knoevenagel reaction. We believe that this protecting strategy can be universally applied for many other secondary and primary amines in polymer materials. Carbamoylaldoximes undergo mechanochemical homolytic bond scission of the oxime N−O bond when embedded into polymers. The subsequent radical mechanism yields mainly the nitrile, upon hydrogen dissociation, and the free amine, upon decarboxylation and hydrogen abstraction. Force‐induced organocatalysis is demonstrated for the activation of a secondary amine.