厦门大学龚磊团队报道了光氧化还原介导的钴催化下醛与羰基或亚胺基化合物的不对称交偶联。相关研究成果于2024年4月8日发表在《美国化学会杂志》。

不饱和键的不对称交叉偶联，由于其极性和反应性，以及缺乏能够对非对映体和对映体进行控制的有效催化体系，在有机合成中遇到了重大障碍。

该文中，研究人员介绍了一种适应性强的光化学钴催化框架，该框架有助于普通醛与广泛的羰基和亚氨基化合物（包括N-酰基腙、芳基酮、醛和α-酮酯）之间的，化学和立体选择性还原交叉偶联。该方法依赖于由光氧化还原诱导的单电子还原，和随后的自由基-自由基偶联驱动的协同机制，所有这些都是由手性钴催化剂精确引导的。

研究人员合成了各种光学富集的β-氨基醇和不对称的1,2-二醇衍生物（80个实例），产率高达90%，立体选择性高达20:1dr，99%ee。特别值得注意的是，这种方法在不依赖任何外部光敏剂的情况下，通过不同的羰基伙伴实现了醛无法实现的光化学不对称转化，从而进一步强调了其多功能性和成本效益。

附：英文原文

Title: Asymmetric Cross-Coupling of Aldehydes with Diverse Carbonyl or Iminyl Compounds by Photoredox-Mediated Cobalt Catalysis

Author: Zhiyong Chi, Jia-Bin Liao, Xiuliang Cheng, Ziqi Ye, Wei Yuan, Yu-Mei Lin, Lei Gong

Issue&Volume: April 8, 2024

Abstract: The asymmetric cross-coupling of unsaturated bonds, hampered by their comparable polarity and reactivity, as well as the scarcity of efficient catalytic systems capable of diastereo- and enantiocontrol, presents a significant hurdle in organic synthesis. In this study, we introduce a highly adaptable photochemical cobalt catalysis framework that facilitates chemo- and stereoselective reductive cross-couplings between common aldehydes with a broad array of carbonyl and iminyl compounds, including N-acylhydrazones, aryl ketones, aldehydes, and α-keto esters. Our methodology hinges on a synergistic mechanism driven by photoredox-induced single-electron reduction and subsequent radical–radical coupling, all precisely guided by a chiral cobalt catalyst. Various optically enriched β-amino alcohols and unsymmetrical 1,2-diol derivatives (80 examples) have been synthesized with good yields (up to 90% yield) and high stereoselectivities (up to >20:1 dr, 99% ee). Of particular note, this approach accomplishes unattainable photochemical asymmetric transformations of aldehydes with disparate carbonyl partners without reliance on any external photosensitizer, thereby further emphasizing its versatility and cost-efficiency.

DOI: 10.1021/jacs.4c01443

Source: https://pubs.acs.org/doi/abs/10.1021/jacs.4c01443