Functionalization of ethylene without polymerization is challenging under photoirradiation conditions. We have demonstrated that the photo-transformation of ethylene can be controllable by merging photoredox and transition-metal catalysis. In our study, the use of different photoredox catalysts was able to modulate the oxidation state of the nickel catalyst. Through different oxidation states, the nickel-catalyzed couplings proceeded via distinct pathways to generate divergent ethylene difunctionalization products selectively from the same feedstock.

Multicomponent catalytic processes that can generate multiple C(sp 3 )C(sp 3 ) bonds in a single step under mild conditions, particularly if the catalysts and substrates are inexpensive, are highly sought-after in chemistry research for complex molecule synthesis. Here, we disclose an efficient Ni-catalysed reductive protocol that chemoselectively merges alkenyl amides with two different aliphatic electrophiles. Starting materials are readily accessible from stable and abundant feedstock and products are furnished in up to >98:2 regioisomeric ratios. The present strategy eliminates the use of sensitive organometallic reagents, tolerates a wide array of complex functionalities and enables regiodivergent addition of two primary alkyl groups bearing similar electronic and steric attributes across aliphatic C=C bonds with exquisite control of site selectivity. Utility is underscored by the concise synthesis of bioactive compounds and post-reaction functionalizations leading to structurally diverse scaffolds. DFT studies revealed that the regiochemical outcome originates from the orthogonal reactivity and chemoselectivity profiles of in situ-generated organonickel species.

A selective palladium-catalyzed trifluoroethylation reaction of indoles has been developed. The C-H bond activation process, using CF 3 CH 2 I as the fluoroalkyl source, can be employed to prepare a variety of 2-CF 3 CH 2 substituted indoles. Moreover, because it displays a wide functional group tolerance, the process can be employed to synthesize CF 3 CH 2 -containing bioactive indoles through late-stage trifluoroethylation. The results of a preliminary mechanistic study and DFT calculations show that a β-diketone, acting as an ionic palladium ligand, plays an important role in governing the efficiency of the palladiumcatalyzed trifluoroethylation reaction by accelerating the oxidative addition step. In contrast, transfer of the indole N-H proton in the palladium center is involved in the rate-determining step.

Cross-coupling reactions have developed into powerful approaches for carbon-carbon bond formation. In this work, a Ni-catalyzed migratory Suzuki-Miyaura cross-coupling featuring high benzylic or allylic selectivity has been developed. With this method, unactivated alkyl electrophiles and aryl or vinyl boronic acids can be efficiently transferred to diarylalkane or allylbenzene derivatives under mild conditions. Importantly, unactivated alkyl chlorides can also be successfully used as the coupling partners. To demonstrate the applicability of this method, we showcase that this strategy can serve as a platform for the synthesis of terminal, partially deuterium-labeled molecules from readily accessible starting materials. Experimental studies suggest that migratory cross-coupling products are generated from Ni(0/II) catalytic cycle. Theoretical calculations indicate that the chain-walking occurs at a neutral nickel complex rather than a cationic one. In addition, the original-site cross-coupling products can be obtained by alternating the ligand, wherein the formation of the products has been rationalized by a radical chain process. 1 1234567890():,; Reductive conditions Redox-neutral conditions Redox-neutral conditions Alkyl reagents Metal migration a Migratory cross-coupling of alkyl electrophiles Ni-catalyzed reductive migratory cross-coupling (Zhu and our group): Pd-catalyzed migratory suzuki-miyaura cross-coupling (Sigman): Ni-catalyzed migratory suzuki-miyaura cross-coupling (this work): b c d Fig. 1 Transition metal-catalyzed migratory cross-coupling. a Migratory cross-coupling of alkyl electrophiles. b Ni-catalyzed reductive migratory crosscoupling. c Pd-catalyzed migratory Suzuki-Miyaura cross-coupling. d The approach developed in this study. ARTICLE NATURE COMMUNICATIONS | https://doi.

An efficient, atom-economical, and regioselective insertion of indoles into terminal alkynes has been realized via cobalt­(III)-catalyzed C–H activation under mild conditions, leading to efficient synthesis of α-gem-vinylindoles. The insertion of the alkynes follows a rare 1,2-selectivity, and silyl alkynes, alkyl alkynes, propargyl alcohols, and protected propargyl amines are all applicable. The mechanism of this hydroarylation system has been studied in detail by a combination of experimental and computational approaches. In the reaction of silyl terminal alkynes, the regioselectivity is dictated by the steric effects of the alkyne substituent, especially in the protonolysis stage. However, for protected propargyl amines, the selectivity results from electronic effects during the insertion step, with protonolysis being insignificant in the determination of selectivity. An internal alkyne also coupled in high efficiency but with low regioselectivity. Comparisons of cobalt, rhodium, and iridium catalysts have also been made in terms of regioselectivity and reactivity, and both are high for cobalt catalysts.