使用单一催化剂产生分子复杂性,其中必要的活化模式随着反应的进行而依次利用,是合成中一个有吸引力的指导原则。这要求每个底物转位都暴露出一种催化剂活化模式 (AM),所有先前或未来的中间体都对这种模式具有抵抗力。虽然麦克米伦将烯胺和亚胺离子活化的美丽结合体现了这一概念,但当代催化其他领域的例子仍然难以捉摸。在这里,我们将此策略扩展到有机光化学。通过利用 (-)-核黄素的两种离散光化学活化模式,可以分别通过能量转移 (ET) 和单电子转移 (SET) 激活途径依次诱导异构化和环化。这种催化方法已被用于模拟香豆素生物合成途径,该途径具有关键的光化学 E → Z 异构化步骤。由于随后的基于 SET 的环化消除了对预官能化芳环的需要,这构成了药学重要支架的新断开连接。
CuH-Catalyzed Asymmetric Reduction of α,β-Unsaturated Carboxylic Acids to β-Chiral Aldehydes
作者:Yujing Zhou、Jeffrey S. Bandar、Richard Y. Liu、Stephen L. Buchwald
DOI:10.1021/jacs.7b12260
日期:2018.1.17
The copper hydride (CuH)-catalyzed enantioselective reduction of α,β-unsaturatedcarboxylicacids to saturated aldehydes is reported. This protocol provides a new method to access a variety of β-chiral aldehydes in good yields, with high levels of enantioselectivity and broad functional group tolerance. A reaction pathway involving a ketene intermediate is proposed based on preliminary mechanistic
Visible light photocatalytic one pot synthesis of <i>Z</i>-arylvinyl halides from <i>E</i>-arylvinyl acids with <i>N</i>-halosuccinimide
作者:Qiong Yu、Kun Yi Yu、Cai Feng Xu、Man-Kin Wong
DOI:10.1039/d1ra08753c
日期:——
efficient visible light photocatalytic strategy to synthesize thermodynamically less stable Z-arylvinyl halides (with up to >99/1 Z/E ratio and 86% yield) was developed. The reaction combined base-mediated halodecarboxylation of E-arylvinyl acids with N-halosuccinimide and visible light Ir-photocatalyzed isomerization of E-arylvinyl halides in a one pot sequential catalytic process.
开发了一种有效的可见光光催化策略来合成热力学上不太稳定的Z-芳基乙烯基卤化物( Z / E比高达 >99/1 ,产率为 86%)。该反应将碱介导的E-芳基乙烯基酸与N-卤代琥珀酰亚胺的卤化脱羧反应和可见光 Ir 光催化的E-芳基乙烯基卤化物的异构化在一锅顺序催化过程中结合起来。