Cyclometallated ruthenium catalyst enables late-stage directed arylation of pharmaceuticals
作者:Marco Simonetti、Diego M. Cannas、Xavier Just-Baringo、Iñigo J. Vitorica-Yrezabal、Igor Larrosa
DOI:10.1038/s41557-018-0062-3
日期:2018.7
Biaryls are ubiquitous core structures in drugs, agrochemicals and organic materials that have profoundly improved many aspects of our society. Although traditional cross-couplings have made practical the synthesis of many biaryls, CâH arylation represents a more attractive and cost-effective strategy for building these structural motifs. Furthermore, the ability to install biaryl units in complex molecules via late-stage CâH arylation would allow access to valuable structural diversity, novel chemical space and intellectual property in only one step. However, known CâH arylation protocols are not suitable for substrates decorated with polar and delicate functionalities, which are commonly found in molecules that possess biological activity. Here we introduce a class of ruthenium catalysts that display a unique efficacy towards late-stage arylation of heavily functionalized substrates. The design and development of this class of catalysts was enabled by a mechanistic breakthrough on the Ru(ii)-catalysed CâH arylation of Nâchelating substrates with aryl (pseudo)halides, which has remained poorly understood for nearly two decades. Nearly two decades after its discovery, the Ru(II)-catalysed CâH arylation of N-chelating aromatics with aryl halides was reinvestigated and a new key reaction intermediate was uncovered. A thorough mechanistic elucidation has now led to the development of a new class of catalysts with unique efficacy towards late-stage arylation of âreal-worldâ compounds.
双芳烃是药物、农用化学品和有机材料中普遍存在的核心结构,对我们社会的许多方面产生了深远的影响。尽管传统的交叉偶联反应使得合成许多双芳烃成为可能,但C–H芳构化反应则是一种更具吸引力和成本效益的构建这些结构单元的策略。此外,通过后期C–H芳构化在复杂分子中引入双芳烃单元,将使我们能够仅用一步访问有价值的结构多样性、新的化学空间和知识产权。然而,已知的C–H芳构化方法并不适用于装饰有极性和精细官能团的底物,而这类官能团通常存在于具生物活性的分子中。在这里,我们介绍一类展现出对重官能化底物的后期芳构化反应具有独特效能的钌催化剂。该类催化剂的设计和开发得益于对钌(II)催化的N-螯合底物与芳香(伪)卤化物之间的C–H芳构化反应的机制突破,这一反应在近二十年来一直未得到充分理解。在其发现近二十年后,N-螯合芳烃与芳香卤化物的Ru(II)催化C–H芳构化反应进行了再研究,并揭示了一个新的关键反应中间体。经过彻底的机制阐明,我们现在成功开发出一类对“现实世界”化合物的后期芳构化具有独特效能的新型催化剂。