Homogeneous, Supramolecular and Bio-Inspired Catalysis (HomKat) group, Van 't Hoff Institute for Molecular Sciences (HIMS), University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands.
Chemistry. 2023 May 26;29(30):e202300336. doi: 10.1002/chem.202300336. Epub 2023 Apr 14.
Transition metal radical-type carbene transfer catalysis is a sustainable and atom-efficient method to generate C-C bonds, especially to produce fine chemicals and pharmaceuticals. A significant amount of research has therefore been devoted to applying this methodology, which resulted in innovative routes toward otherwise synthetically challenging products and a detailed mechanistic understanding of the catalytic systems. Furthermore, combined experimental and theoretical efforts elucidated the reactivity of carbene radical complexes and their off-cycle pathways. The latter can imply the formation of N-enolate and bridging carbenes, and undesired hydrogen atom transfer by the carbene radical species from the reaction medium which can lead to catalyst deactivation. In this concept paper, we demonstrate that understanding off-cycle and deactivation pathways not only affords solutions to circumvent them, but can also uncover novel reactivity for new applications. In particular, considering off-cycle species involved in metalloradical catalysis can stimulate further development of radical-type carbene transfer reactions.
过渡金属自由基型卡宾转移催化是一种可持续且原子经济性的生成 C-C 键的方法，特别适用于精细化学品和药物的合成。因此，人们投入了大量的研究来应用这种方法学，从而为原本具有挑战性的合成产物开辟了创新途径，并对催化体系有了详细的机理理解。此外，实验和理论的综合努力阐明了卡宾自由基配合物的反应性及其非循环途径。后者可能意味着 N-烯醇盐和桥连卡宾的形成，以及卡宾自由基物种从反应介质中不必要的氢原子转移，这可能导致催化剂失活。在本概念论文中，我们证明了理解非循环和失活途径不仅提供了规避它们的方法，还可以为新的应用揭示新的反应性。特别是，考虑到涉及金属自由基催化的非循环物种可以刺激自由基型卡宾转移反应的进一步发展。
