A transition-metal-free one-pot tandem reaction of readily available N-alkenyl indoles, DABSO and 4-alkyl-1,4-dihydropyridines (alkyl-DHPs) for synthesis of alkylsulfonyl-containing polycyclic indoles at room temperature under visible light irradiation has been accomplished. This transformation occurs smoothly under mild conditions to enable facile access to various alkylsulfonyl-containing polycyclic indoles with high efficiency, wide substrate scope and good functional group tolerance, and can proceed on a gram-scale. The efficacy of the current catalysis arises from the use of organic dye Eosin Y as the photocatalyst and economical K2S2O8 as oxidant.

Achieving precise stereocontrol in macromolecular synthesis under mild conditions remains a fundamental challenge in polymer chemistry. Herein, an efficient and highly syndiospecific polymerization of methyl methacrylate (MMA) is realized by using Lewis pairs composed of rare-earth (RE) aryloxides and phosphines, affording syndiotactic PMMA (up to 90.3% rr at 25 degrees C) with well-controlled molecular weight (near-quantitative initial efficiency, M n up to 21.0 x 104 g/mol). This methodology exhibits broad applicability, extending to diverse methacrylate monomers such as allyl, benzyl, di(methylamino)ethyl, and methoxyethyl derivatives (80.7-90.0% rr). Mechanistic studies, including kinetic analysis and chain-end characterization, support a bimolecular, activated-monomer propagation pathway. Crystallographic topographic maps reveal that moderate steric hindrance in RE Lewis acid phenolate ligands is crucial for the optimal polymerization stereoselectivity.

Herein, we report a regioselective decarboxylative deuteroalkylation of olefins. This protocol enables the previously unexplored functionalization of 2-vinylpyridine with redox-active esters (RAEs) employing zinc powder as the reductant, thereby addressing the limitations of prior approaches. The protocol tolerates a wide range of functional groups and complex natural product derivatives. Collectively, the diversification and synthetic versatility of deuterium-labeled drug molecules, particularly through site-specific deuteration, constitute a well-established and effective strategy in modern organic synthesis and drug discovery.

To tackle some shortcomings of the classic Fischer indole synthesis employing aldehydes as starting materials, we report herein a reductive Fischer-type indole synthesis based on carboxylic acids. This method comprises a tandem sequence involving B(C6F5)3-catalyzed hydrosilylation of carboxylic acids with Et3SiH to generate the corresponding O,O-disilyl acetals, p-TsOH-mediated transamination with arylhydrazines to form hydrazones, and a late-stage Fischer indole cyclization. In this manner, carboxylic acids act as surrogates of aldehydes. Using this one-pot protocol, a series of 3-substituted indoles, including 3,4-, 3,5-, and 3,6-disubstituted indole derivatives have been synthesized. The utility of this protocol is demonstrated by the efficient synthesis of the versatile natural product 3-methylindole, the key intermediate in the commercial production of the antidepressant drug Vilazodone (Viibryd), and the core scaffold of one of the most frequently prescribed agents for the treatment of hypercholesterolemia-all from inexpensive, commercially available carboxylic acids and arylhydrazines. The one-pot reaction tolerates several functional groups such as halogen (F, Cl, Br, I), MeO, CN, and CF3, which are either key moieties for the development of medicinal and agrochemical agents, or can be used as a handle for the further elaboration of the indole products, as demonstrated by the two-step synthesis of a tetracyclic indole derivative.

Reductive homologation of carbon monoxide (CO) serves as a pivotal process in C1 chemistry, mimicking the chain-growth mechanisms of industrial Fischer-Tropsch synthesis. Herein, the nickel-catalyzed selective homologation of CO with dipyrromethene ligand supported magnesium alkyl compounds through a Mg/Ni cooperative strategy is reported. Reaction of magnesium alkyl compounds L1MgR·Et2O [L1 = 1,9-di(isopropylphenyl)-5-mesityldipyrromethene; R = nBu, Et] with CO (1 bar) in the presence of 20 mol % Ni(COD)2 (COD = 1,5-cyclooctadiene), selectively yielded the acyclic CO tetramerization products (L1Mg)2(μ-C4O4)R2. By tuning the steric hindrance of the ancillary ligands, the reaction pathways can be directed to form the linear CO trimerization compound (L2Mg)2(μ-C3O3)nBu2 (L2 = 1,5,9-trimesityldipyrromethene) and the CO dimerization compound (L3Mg)2(μ-C2O2)nBu2 [L3 = 1,9-di(1-adamantyl)-5-mesityldipyrromethene], respectively. Moreover, the Mg/Ni-cooperative CO insertion species [L2Mg(CO)nBu]3[Ni4(CO)7] was isolated from the stoichiometric reaction of L2MgnBu·Et2O with Ni(COD)2 under a CO atmosphere. This species further reacted with CO to form the trimerization product (L2Mg)2(μ-C3O3)nBu2, confirming its active role in the CO homologation process. The formation mechanism of the acyclic CO tetramerization compound was elucidated by density functional theory calculations, which mainly involved the CO insertion, C-C coupling, and carbene dimerization processes, verifying the critical role of the Mg/Ni cooperative strategy in the reaction.

A ruthenium-catalyzed method has been developed for the direct C2-H selenylation of (benz)imidazole, enabling efficient selenium incorporation at the C2 position to yield diverse selenylated derivatives. This system operates under mild conditions with a broad substrate scope, excellent functional group tolerance, and high regioselectivity. Notably, diaryl disulfides were also successfully employed under identical conditions.

We report a practical and chemoselective method for the direct reduction of tertiary amides to amines under mild conditions using Vaska's Ir-complex with low catalyst loading and inexpensive Brønsted acids.

This work reports the ortho-selective C-H alkenylation of diverse pyridines with alkynes catalyzed by the heterometallic Mg-Ni-Mg complex [(LMg)2Ni(C2H4)2] {L = [(DippNCMe)2CH]- and Dipp = 2,6-iPr2C6H3}. This protocol delivers a wide range of C2-alkenylpyridines with high regio- and stereoselectivities (>19:1 rr and >19:1 E/Z). The stoichiometric reaction of [(LMg)2Ni(C2H4)2] with 4-methylpyridine led to the isolation and structural characterization of a key C-H metalation intermediate, which provides direct evidence for a Mg-Ni cooperative ortho C-H activation process.

Heterotrimetallic Mg–Ni–Mg complexes containing nickela-bis-cyclopropane cores were obtained, which could be facilely transformed into a nickela-mono-cyclopropane complex upon treatment with molecular CO.

Reaction of LAmZnI [LAm = tBuC(N-DIPP)2, DIPP = 2,6-iPr2-C6H3] with KC8 in the presence of cyclic (alkyl)(amino)carbene (cAAC) affords a stable radical complex [LAmZn(cAAC)]• (3). Single-crystal structural analysis of 3 shows a short Zn─C bond and concomitant elongation of C─N bond within the cAAC ligand, indicating a significant π-backbonding from the metal to the cAAC ligand. EPR spectroscopy and DFT calculations reveal that the spin density is mainly localized on the carbenic carbon atom, with a small portion on the zinc center. Complex 3 exhibits zinc-centered radical reactivity as demonstrated by reactions with 2,2,6,6-tetramethyl-1-piperidinyloxy, iodobenzene, trimethylsilyl azide, and [FeCp(CO)2]2, all of which occur at the zinc center and yield the corresponding Zn(II) complexes.

Metal-substituted carbenes are fundamentally important as they represent the limiting configurations of metal carbynes. However, structurally characterized examples are still rare, and their reactivity remains underexplored. Herein, we report the first synthesis, characterization, and reactivity studies of zinc-substituted carbenes. UV irradiation of zinc diazoalkyl complexes LZnC(N2)P [L = [(ArNCMe)2CH]-, P = (DippNCH2)2P, Ar = Dipp or Mes, Dipp = 2,6- i Pr2C6H3, Mes = 2,4,6-Me3C6H2] generates Zn(ii)-substituted carbenes LZnCP with concomitant N2 release. The Zn-C-P moiety features nearly linear carbene centers, deviating from conventional carbene geometry. Computational studies indicate a singlet ground state stabilized through synergistic effects of C-P π-interaction and carbene lone-pair delocalization towards the Zn center. Treatment of LZnCP with CO2 selectively affords zincated ketene via nucleophilic attack and tandem C[double bond, length as m-dash]O double bond cleavage. It reacts with 4-dimethylaminopyridine to form a carbene-Lewis base adduct exhibiting electrophilic reactivity. Furthermore, zinc-substituted carbenes enable direct transition metals coordination to give the heterobimetallic Zn/M (M = Ag+, Au+, Ni) μ-carbyne complexes.

Since the seminal report on dizincocene [Zn2Cp*2] (Cp* = C5Me5) by Carmona and coworkers, zinc-zinc bonded complexes have garnered significant research interest owing to their structural versatility and applications in both stoichiometric and catalytic processes. Building on the elegant review in 2012, this feature article briefly reviews decadal advances in the synthesis and reactivity of Zn-Zn bonded species. We specifically highlight methodological innovations in synthesizing these species, including novel reductant systems, ligand substitution strategies, and zinc hydride dehydrocoupling protocols. A survey of their reactivity is subsequently presented, encompassing heterometallic complex formation, small molecule activation, and catalytic transformations. The elucidation of novel reaction modes, expansion of catalytic frontiers, and exploration of non-classical Zn-Zn bonding configurations represent compelling yet formidable challenges in this domain; thus, concerted research efforts are required in the future.

Research on CO activation and homologation is pivotal for promoting sustainable chemistry and the construction of Cn molecular blocks. This work reports the nickel-catalyzed reduction of CO by magnesium alkyl compounds utilizing a bimetallic Mg/Ni synergistic strategy. The exposure of β-diketiminato ligand-supported magnesium monoalkyl compounds LMgR (L=[(DippNCMe)2CH]-, Dipp=2,6-iPr2C6H3; R=nBu, CH3, C5H9) to 1 bar of CO in the presence of 10 mol % Ni(COD)2 (COD: 1,5-cyclooctadiene) selectively afforded the CO single-insertion product [LMg(CHO)C5H8], the dimerization product [(LMg)2(μ-C2O2)(CH3)2], and the linear trimerization product [(LMg)2(μ-C3O3)(nBu)2], respectively, depending on the R group. In addition, transition metal-stabilized carbene species resulted from CO activation were successfully isolated through stoichiometric control experiments. The profiles of CO trimerization and dimerization were further elucidated by density functional theory calculations, which confirmed the crucial roles of Mg/Ni cooperation and carbene species in the current reaction.

A series of amine-bridged bis(phenolate) rare-earth (Sc, Y) aryloxides was synthesized and characterized. These complexes were successfully used for the controlled Lewis pair polymerization (LPP) of functional acrylamides in combination with phosphines, affording a new type of polyacrylamides with predictable molecular weight and low molecular weight distribution. The living nature of this LPP was verified by near-quantitative initiation efficiencies, a linear increase of molecular weight vs monomer-to-initiator ratio and monomer conversion, chain extensions, and the synthesis of well-defined block copolymers. The mechanistic studies were performed through the isolation of a zwitterionic intermediate as well as the end-chain analysis of oligomers, showcasing a rare-earth/phosphine cooperation. Furthermore, the resultant polyacrylamides exhibit outstanding thermal stability and great potential for application in photovoltaic devices. (c) 2024 Chinese Society of Rare Earths. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Transition metal-diene complexes constitute a fundamental class of organometallic compounds, in which conjugated dienes typically behave as neutral π-donor ligands. While doubly reduced enediyl derivatives have been occasionally documented in the literatures, dinuclear transition metal complexes featuring such bonding motifs have not been explored. Herein, we report a heterometallic complex [(LMg)2Ni2(C4H6)2] (L = [(DIPPNCMe)2CH]-, DIPP = 2,6-iPr2C6H3) featuring a linear Mg-Ni-Ni-Mg bonded chain, which was formed by the reaction of LMgBu·Et2O with Ni(cod)2 (cod: 1,5-cyclooctadiene). Experimental and computational studies reveal two s-trans-butadiene ligands bridging the Ni-Ni bond in a doubly reduced enediyl configuration. This unique bonding arrangement results in a dinickela-bicyclo[4,4,0]-decadiene framework containing a heterocyclic trans-cycloalkene moiety. Treatment of [(LMg)2Ni2(C4H6)2] with the additional butadiene afforded [(LMg)2Ni2(C4H6)3], involving three C4H6 ligands bound to nickel centers, in which they behave as two doubly reduced enediyl ligands and one neutral butadiene ligand. In contrast, upon exposure to carbon monoxide (CO), a ligand exchange reaction occurred, yielding [(LMg)2Ni2(C4H6)(CO)4] with one C4H6 ligand, which is considered as a dinickelacyclo-4-hexene supported by Mg-metalloligands.

Heterometallic polyhydride complexes containing main-group metals and transition metals have attracted much attention due to their versatile MHn units and potential metal-metal synergies for molecular transformation. In this work, we report that a heterometallic Mg-Ni-Mg polyhydride complex [(LMg)2NiH4] {L = [(DippNCMe)2CH]-, Dipp = 2,6-iPr2C6H3} is able to catalyze the selective H/D exchange of ortho C(sp2)-H bonds of pyridine derivatives with D2 to obtain deuterium-labeled compounds with high isotopic incorporation. Moreover, benzylic C(sp3)-H bonds are also successfully labeled using D2 in the presence of [(LMg)2NiH4]. Pharmaceuticals with high isotopic incorporation have also been achieved with this catalytic system. Stoichiometric reactions of [(LMg)2NiH4] with pyridines yield the Mg-Ni cooperative mono- and bis-ortho C-H bond activation complexes, i.e., trihydride [(LMg)2NiH3(NC5H4R)(NC5H3R)] (R = Ph, Et) and dihydride [(LMg)2NiH2(NC5H3Ph)2], which are considered as active intermediates in the catalytic process.

The enantioselective C-H addition of anilines to alkenes represents an ideal protocol for the synthesis of chiral aromatic amines in terms of step- and atom-economy. However, this field remains predominantly unexplored. Herein, a series of newly designed bulky chiral anilido-oxazoline ligand precursors were synthesized, and the corresponding rare-earth metal alkyl complexes were obtained successfully. The resultant scandium complexes exhibit high regioselectivity for the ortho-C-H addition of tertiary anilines to unactivated alkenes, providing a wide range of chiral alkylated anilines in high yields (up to 98% yield) with excellent enantioselectivity (up to 98% ee). Moreover, the addition products can be easily converted into biorelevant derivatives and pharmacophore-containing skeletons.

This work reports the divergent metalation of trimethylsilyldiazomethane (Me3SiCHN2) with magnesium methyl compounds, yielding magnesium nitrilimine, diazoalkyl, and hydrazone complexes. Treatment Me3SiCHN2 with a beta-diketiminato ligand-supported magnesium methyl compound L 1 MgCH3THF (L 1 = [(DIPPNCMe)2CH]-, DIPP = 2,6- i Pr2C6H3) generates a magnesium nitrilimine complex [L 1 Mg(mu-N-NCSiMe3)]2 (2) accompanied by methane elimination. Substitution of the supporting ligand with the more sterically encumbering variant [(DIPPNC t Bu)2CH]- (L 2 ), results in the formation of a magnesium diazoalkyl complex [L 2 Mg(mu-kappa 2-C(SiMe3)NN)]2 (4). Crystallographic analyses confirm dimeric assemblies for both 2 and 4, yet reveal divergent ligation modes at the CNN unit. Addition of a Lewis-basic donor, 4-dimethylaminopyridine (DMAP), to the system shifts the product selectivity, yielding a magnesium hydrazone species L 1 Mg(DMAP)(eta 2-N(Me)NCHSiMe3) (5) via insertion of the terminal nitrogen atom of diazoalkane into the Mg-C bond.

Frustrated Lewis pair (FLP) chemistry has undergone remarkable growth, among which rare-earth metal-based Lewis pairs have exhibited unique reactivity in recent years. Herein, treatment of the intramolecular Sc/P Lewis pair, i.e., (ArO)2ScN(tBu)PPh2 (1, Ar = 2,6-tBu2-C6H3), with pyridotetrazole resulted in the formation of an FLP nitrene adduct with N2 elimination, offering additional insights into the mechanism of transition-metal-catalyzed denitrogenative annulation of pyridotetrazole. Reactions of complex 1 with 1,3,5-triazine and benzo[c]cinnoline generated FLP-type products via Sc/P 1,2-addition to the CN bond and the NN bond, respectively. Furthermore, treatments of 1 with phenylacetylene, diazo, and azide compounds were also investigated, leading to the formation of a variety of metallacyclic complexes displaying typical FLP behaviors.