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Constructing structurally robust and catalytically active metal nanoclusters for catalyzing multi‐component reactions is an interesting while challenging task. Inspired by Lewis acid and Lewis base catalysis, we realized the combination of both Lewis acid and Lewis base sites on the surface of a stable gold nanocluster Au35Cd2. The catalytic potential of Au35Cd2 in four‐component Ugi reaction was explored, demonstrating high activity and exceptional recyclability. In‐depth mechanism studies indicate that the catalytic synergy of the Lewis acid/base pair is crucial for the high efficiency of Au35Cd2‐catalyzed Ugi reaction. Bearing the stable structure, multiple activation sites and hierarchical chirality, Au35Cd2 is expected to display further interesting catalytic performance such as asymmetric catalysis. [ABSTRACT FROM AUTHOR]

Ligand-protected metal nanoclusters provide an ideal platform for investigating photoredox catalysis. The central challenge is balancing their stability and catalytic activity. Here we show a photochemical reduction–oxidation cascade method for synthesizing an Au8Cu6 nanocluster, which features a robust structure and active surface. Photoredox catalytic activity of Au8Cu6 is developed for the functionalization of alkynes under oxidative conditions. Mechanism studies based on the precise structure reveal the catalytic process of the Au8Cu6 nanocluster. Oxidant-dependent selectivity of Au8Cu6 catalysis is developed for chemodivergent synthesis of mono- and di-functionalized products in high efficiency. The results will stimulate more research on metal nanocluster synthesis and catalysis. Ligand-protected metal nanoclusters provide an ideal platform for investigating the balance of stability and activity in photoredox catalysis. Here, the authors apply a photochemical reduction–oxidation cascade method to synthesize an Au8Cu6 nanocluster with a robust structure and active surface. [ABSTRACT FROM AUTHOR]

Selective functionalization of allenic C(sp2)‐H is an ideal approach to upgrading simple allenes to synthetically useful allenes, albeit suffering from challenges associated with inert reactivity and inferior selectivity. Inspired by energy chemistry, a catalytic hydrogen evolution reaction (HER) strategy was leveraged to selectively activate weakly acidic allene C(sp2)‐H bonds in a reductive mode. An array of [Co2O2] metallacycle complexes were readily devised starting from amino acids, and they were demonstrated as robust HER catalysts, which would selectively break allenic C(sp2)‐H bonds to release hydrogen. With the newly developed HER catalyst, regioselective electrochemical functionalization of allenic C(sp2)‐H with alcoholic α C(sp3)‐H was unprecedentedly achieved. This strategy features excellent regioselectivity, unconventional chemoselectivity, good functional‐group tolerance (62 examples), and mild conditions. Mechanism experiments revealed a reactive hydroxy‐coordinated cobalt(II) species in the reaction. Density functional theory (DFT) calculations were also conducted to rationalize the regioselectivity observed in the reaction. [ABSTRACT FROM AUTHOR]

Cross-dehydrogenative coupling of C(sp3)-H bonds is an ideal approach for C(sp3)-C(sp3) bond construction. However, conventional approaches mainly rely on a single activation mode by either stoichiometric oxidants or electrochemical oxidation, which would lead to inferior selectivity in the reaction between similar C(sp3)-H bonds. Herein we describe our development of a paired electrocatalysis strategy to access an unconventional selectivity in the cross-dehydrogenative coupling of alcoholic α C(sp3)-H with allylic (or benzylic) C-H bonds, which combines hydrogen evolution reaction catalysis with hydride transfer catalysis. To maximize the synergistic effect of the catalyst combinations, a HER catalyst pentacoordinated Co-salen is disclosed. The catalyst displays a large redox-potential gap (1.98 V) and suitable redox potential. With the optimized catalyst combination, an electrochemical cross-dehydrogenative coupling protocol features unconventional chemoselectivity (C-C vs. C-O coupling), excellent functional group tolerance (84 examples), valuable byproduct (hydrogen), and high regio- and site-selectivity. A plausible reaction mechanism is also proposed to rationalize the experimental observations. Cross-dehydrogenative coupling (CDC) of C-H bonds is an ideal approach for C-C bond construction but suffers from low selectivity of similar C-H bonds. Here, the authors describe a highly selective paired electrocatalysis strategy towards CDC combining hydrogen evolution reaction catalysis with hydride transfer catalysis. [ABSTRACT FROM AUTHOR]

A gold nanocluster Au17Cd2(PNP)2(SR)12 (PNP=2,6‐bis(diphenylphosphinomethyl)pyridine, SR=4‐MeOPhS) consisting of an icosahedral Au13 kernel, two Au2CdS6 staple motifs, and two PNP pincer ligands has been designed, synthesized and well characterized. This cadmium and PNP pincer ligand co‐modified gold nanocluster showed high catalytic efficiency in the KA2 reaction, featuring high TON, mild reaction conditions, broad substrate scope as well as catalyst recyclability. Comparison of the catalytic performance between Au17Cd2(PNP)2(SR)12 and the structurally similar single cadmium (or PNP) modified gold nanoclusters demonstrates that the co‐existence of the cadmium and PNP on the surface is crucial for the high catalytic activity of the gold nanocluster. This work would be enlightening for developing efficient catalysts for cascade reactions and discovering the catalytic potential of metal nanoclusters in organic transformations. [ABSTRACT FROM AUTHOR]