4-CN-pyridine is a widely applied 4-pyridinylation reagent for diverse transformations. Conventionally, the reaction proceeds via an open-shell radical cross-coupling pathway. Following our previous study, in this work, we report the Pd-catalyzed allyl 4-pyrinylation reaction under electrochemical conditions. The reaction proceeds via radical-polar crossover pathway in which the role of phosphine ligand in reactivity and selectivity was extensively investigated.
β-Amino acids have a wide range of applications in the field of pharmaceuticals. Utilizing a combination strategy of nickel catalysis and paired electrolysis, a catalytic α-arylation protocol of carbonyl compounds has been developed. This protocol affords various α-aryl-α-cyanoacetates, which can be reduced to high-value-added α-aryl-β-amino acids. The cross-coupling reaction of electron-deficient aryl bromides with α-cyanoacetates achieves the expected products with good yields and functional group compatibility under mild conditions. Excessive electron-richness in initial aryl bromides facilitates the self-coupling of desired products. DFT calculations confirm that the presence of electron-rich aryl substitutions decreases the reduction potentials of the product anions, making them more susceptible to oxidation at the anode. Based on electroanalyses and mechanistic studies, it is proposed that the enolate intermediate, rather than the radical intermediate, participates in the catalytic cycle.
In recent years, the incorporation of deuterium atoms into organic compounds has emerged as a vital focus in the development of pharmaceutical molecules. This trend is driven by the increasing recognition of the significance of compounds containing deuterium atoms across various domains, including materials and biopharmaceuticals, where they have found widespread applications in mechanistic studies within the realms of chemistry and biology. Meanwhile, organic electrochemistry, as a relatively environmentally friendly catalytic mode with broad adaptability to redox reactions, has emerged as a crucial alternative to traditional halogen-deuterium exchange in the context of the reduction deuteration of halides. This approach circumvents the uses of transition metal catalysts and toxic deuterated reagents which are commonly employed in traditional methods. Notably, electrocatalytic dehalogenation with deuterium incorporation typically relies on heavy water as the deuterium source, ensuring high yields and significant deuterium incorporation. In recent years, electrochemically dehalogenative deuteration of halides has made substantial progress, providing critical support for the synthesis and development of deuterated compounds. This article offers a comprehensive overview of the latest advancements in electrochemical reductive deuteration of both aromatic and alkyl halides, categorizing the progress according to the type of halide and delving into the underlying reaction mechanisms.