Cross-electrophile coupling of two distinct organic halides has emerged as a powerful strategy for expanding chemical spaces. In this context, stereoselective nickel catalysis holds high synthetic value, yet remains relatively underdeveloped.. Herein, we report a zirconaaziridine-mediated cross-electrophile coupling protocol catalyzed by a tripyridyl-ligated nickel complex, enabling the diastereoselective synthesis of substituted cyclohexyl, tetrahydropyranyl, and piperidyl scaffolds with high levels of stereocontrol and broad functional group tolerance. Experimental investigations including kinetic and computational studies support a "sequential reduction" mechanism, wherein redox-transmetalation between a Ni(II) dihalide complex and zirconaaziridine is proposed to generate a monovalent Ni(I) halide species alongside a Cp2Zr(III) intermediate that facilitates the conversion of an alkyl iodide into the corresponding C(sp3) radical.

Reductive cross-electrophile coupling of organic halides facilitated by open-shell Ni catalysis has emerged as a powerful strategy for the efficient construction of molecular complexity. Despite significant advances, the diversity of catalytic systems has remained relatively limited, as the reductive potential of Ni species is highly dependent on the ligand employed. Recently, we identified organometallic zirconaaziridine as an effective redox-transmetalating reagent in Ni catalysis, enabling two distinct applications: diastereoselectively modulable catalytic C(sp(2))-glycosylation and the selective consecutive assembly of C(sp(2)) fragments at a methylene CH2 carbon. Notably, extensive experimental and computational studies support a sequential reduction mechanism, wherein oxidative addition of Ni(I)-X to C(sp(2))-I, halide abstraction of C(sp(3))-I by C(sp(2))-Ni(I), and radical capture by C(sp(2))-Ni(II) proceed with high selectivity. 1 Introduction 2 Redox-Transmetalation 3 Example 1: Diastereoselective C(sp(2))-Glycosylation 4 Example 2: Consecutive Three-Component Cross-Electrophile Coupling 5 Summary

The chemical upcycling of ester-based plastics and biomass-derived molecules offers a promising strategy for addressing environmental and ecological challenges. The development of sustainable catalytic processes to convert these abundant feedstocks into value-added chemicals is therefore of great significance. In this study, we introduce a protocol for (EtO)3SiH-mediated, Zr-catalyzed reductive amination, which efficiently converts polyester waste into synthetically valuable amines, amino alcohols, and pyrroles with good yields. Significantly, this method enables the selective valorization of common plastics, including poly(ethylene terephthalate) (PET), polybutylene succinate (PBS), polycaprolactone (PCL), and polylactic acid (PLA), without the undesired reduction of their ester groups to monomeric alcohols. Moreover, this protocol demonstrates broad applicability to biomass-derived esters and lactones, underscoring its potential in converting renewable materials. Importantly, our studies address the essential role of organosilane in use and suggest a dual catalytic cycle, where zirconocene's Lewis acidity facilitates the aminolysis of polyesters, followed by zirconium hydride catalysis driving the reductive amination of the resulting amides into the target amines.

CpRu-catalyzed asymmetric allylic alkylation serves as a versatile synthetic tool but remains underexplored. Herein, we report a relay system combining achiral Rh2(OAc)4 and a chiral pyridine-oxazoline-ligated Cp*Ru catalyst for asymmetric coupling of cinnamyl chlorides with diazo esters, generating silyl enol ethers in situ as key nucleophilic intermediates. This strategy affords chiral tetrahydrofuran derivatives with two vicinal stereocenters. Catalyst compatibility, excellent regioselectivity, and good enantioselectivity highlight its potential. Computational studies reveal the crucial role of Ru-centered chirality in reaction control.

In the realm of organic synthesis, the catalytic and stereoselective formation of C-glycosidic bonds is a pivotal process, bridging carbohydrates with aglycones. However, the inherent chirality of the saccharide scaffold often has a substantial impact on the stereoinduction imposed by a chiral ligand. In this study, we have established an unprecedented zirconaaziridine-mediated asymmetric nickel catalysis, enabling the diastereoselective coupling of bench-stable glycosyl phosphates with a range of (hetero)aromatic and glycal iodides as feasible coupling electrophiles. Our developed method showcases a broad scope and a high tolerance for various functional groups. More importantly, precise stereocontrol toward both anomeric configurations of forming C(sp(2))-glycosides can be realized by simply utilizing the popular chiral bioxazoline (biOx) ligands in this reductive Ni catalysis. Regarding the operating mechanism, both experimental and computational studies support the occurrence of a redox transmetalation process, leading to the formation of a transient, bimetallic Ni-Zr species that acts as a potent and efficient single-electron reductant in the catalytic process.

Ni-catalyzed multicomponent cross-couplings have emerged as a powerful strategy for efficiently constructing complex molecular architectures from a diverse array of organic halides. Despite its potential, selectively forming multiple chemical bonds in a single operation, particularly in the realm of cross-electrophile coupling catalysis, remains a significant challenge. In this study, we have developed a consecutive open-shell reductive Ni catalysis, enabling the formation of two geminal C(sp3)-C(sp2) bonds from two stereoelectronically similar C(sp2)-I reactants in conjunction with a methylene electrophile. Using zirconaaziridine and elemental Mg0 as reductants, this protocol exhibits broad applicability across a wide range of (hetero)aromatic, alkenyl, and glycal halides, allowing for the rapid assembly of medicinally relevant scaffolds with excellent functional group tolerance. Further kinetic studies suggest a dual "sequential reduction" catalytic process facilitated by a zirconaaziridine-mediated redox-transmetalation process in Ni catalysis. Notably, the concerted oxidative addition of Ni(I)-I across a C(sp2)-I bond, as well as the halide atom abstraction among various C(sp3) electrophiles by an open-shell C(sp2)-Ni(I) species, can proceed with high selectivity. The use of an unsymmetrical methylene electrophile with exceptionally high reactivity in XEC resulted in the rapid accumulation of a benzylic or allylic electrophile intermediate at the outset of reaction, thereby finely controlling the coupling sequence.

An amide group, which is a common structural motif of peptides and biologically active molecules, is a highly attractive target for catalytic transformations. Despite its high synthetic potential, the chemical inertness of the amide bond, owing to its resonance sta-bilization, has rendered this approach challenging. Existing cata-lytic modes essentially include metal-catalyzed carbon-nitrogen bond activation, transamidation, and catalytic amide reduction. Herein, we report an unprecedented protocol of catalytic reduc-tive transamination of amides to amines of exchanged identities. Through the intermediacy of aminals, combinations of amides with a wide range of external amines lead to a variety of mono -and diamines in good yields with high compatibility of functional groups and retentions of chirality. Regioselective post -modifica-tions of oligomeric peptide derivatives bearing multiple amide mo-tifs have also been realized, and the origin of site-selectivity has been explained by both experimental studies together with DFT calculations.

Transition metal catalysis in the frontier of organic transformations has played a particularly important role to build in molecular complexity from simple and commercially avaiblable starting materials. While most examples have relied on the uses of noble metals, variants being abundant, less toxic and environmentally friendly have been attracted much attentions since decades. This chapter aims to comprehensively present the advances of hydrometallation in modern chemistry, emphasizing the potential prospects of nickel, copper, cobalt and iron in the catalysis of hydrogenation, hydroboration, hydrosilylation, hydrocarbonation etc.

Transition metal-catalyzed cross-electrophile coupling (XEC) is a powerful tool for forging C(sp(2))-C(sp(2)) bonds in biaryl molecules from abundant aromatic halides. While the synthesis of unsymmetrical biaryl compounds through multimetallic XEC is of high synthetic value, the selective XEC of two heteroaromatic halides remains elusive and challenging. Herein, we report a homogeneous XEC method, which relies on a zirconaaziridine complex as a shuttle for dual palladium-catalyzed processes. The zirconaaziridine-mediated palladium (ZAPd)-catalyzed reaction shows excellent compatibility with various functional groups and diverse heteroaromatic scaffolds. In accord with density functional theory (DFT) calculations, a redox transmetallation between the oxidative addition product and the zirconaaziridine is proposed as the crucial elementary step. Thus, cross-coupling selectivity using a single transition metal catalyst is controlled by the relative rate of oxidative addition of Pd(0) into the aromatic halide. Overall, the concept of a combined reducing and transmetallating agent offers opportunities for the development of transition metal reductive coupling catalysis.

C(sp3)-H bond functionalization has emerged as a robust tool enabling rapid construction of molecular complexity from simple building blocks, and the development of asymmetric versions of this reaction creates a powerful methodology to access enantiopure sp3-rich materials. Herein, we report the stereoselective functionalization of C(sp3)-H bonds of cyclic ethers employing a photochemically active diaryliodonium salt in combination with an anionic phase-transfer catalyst. The synthetic strategy outlined herein allows for regio- and stereochemical control in the α-C-H acetalization of furans and pyrans using alcohol nucleophiles, thus providing the ability to control the configuration at the stereogenic exocyclic acetal carbon.

Light driven excitation of gold nanoparticles (GNPs) has emerged as a potential strategy to generate hot carriers for photocatalysis through excitation of localized surface plasmon resonance (LSPR). In contrast, carrier generation through excitation of interband transitions remains a less explored and underestimated pathway for photocatalytic activity. Photoinduced oxidative etching of GNPs with FeCl3 was investigated as a model reaction in order to elucidate the effects of both types of transitions. The quantitative results show that interband transitions more efficiently generate hot carriers and that those carriers exhibit higher reactivity as compared to those generated solely by LSPR. Further, leveraging the strong π-acidic character of the resulting photogenerated Au+ hole, an interband transition induced cyclization reaction of alkynylphenols was developed. Notably, alkyne coordination to the Au+ hole intercepts the classic oxidation event and leads to the formation of the catalytically active gold clusters on subnanometer scale.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Pentamethylcyclopentadienyl (Cp*) based transition-metal-catalyzed C-H functionalization has become an important synthetic tool for the construction of molecular complexity from simple starting materials. Despite their high potential, the corresponding asymmetric transformations with late transition metal complexes, where the chirality solely stems from the Cp fragment, are completely elusive. We have elaborated facile and flexible syntheses of two tunable classes of enantiopure C2-symmetric Cp ligands as the stereo-controlling elements. The viability of our novel concept to achieve high level of stereoselectivity was proved by four applications on asymmetric Rh(III)-catalyzed C-H functionalizations such as enantioselective synthesis of dihydroquinolones, asymmetric C-H allylations of benzamides, enantioselective hydroarylation to dihydrobenzofurans and asymmetric synthesis of isoindolones. Both classes of chiral CpX*-Rh complexes demonstrate high reactivity, delivering the products with excellent regio- and enantio-control.

The demand for efficient chiral cyclopentadienyl ligands (Cp-x) has increased significantly in recent years, partly because Cp*Rh(III) species have been developed as powerful catalysts for directed C-H functionalization reactions. However, a lack of suitable Cp-x ligands has hampered the development of the corresponding enantioselective processes. We report expansions of the libraries of two generations of Cp-x ligands and their corresponding rhodium(I) complexes. The potential of the rhodium complexes as catalysts was evaluated in enantioselective C-H functionalizations involving cyclizations across tethered aldehydes. The mild reaction conditions permit the syntheses of hydroxychromanes and phthalides in good yields and high enantioselectivities.

ChemInformVolume 46, Issue 45 Heterocyclic Compounds ChemInform Abstract: Chiral Cyclopentadienyl Ligands Enable a Rhodium(III)-Catalyzed Enantioselective Access to Hydroxychromanes and Phthalides. Baihua Ye, Baihua Ye Inst. Chim. Sci. Eng., Ec. Polytech. Fed. Lausanne, CH-1015 Lausanne, Switz.Search for more papers by this authorNicolai Cramer, Nicolai Cramer Inst. Chim. Sci. Eng., Ec. Polytech. Fed. Lausanne, CH-1015 Lausanne, Switz.Search for more papers by this author Baihua Ye, Baihua Ye Inst. Chim. Sci. Eng., Ec. Polytech. Fed. Lausanne, CH-1015 Lausanne, Switz.Search for more papers by this authorNicolai Cramer, Nicolai Cramer Inst. Chim. Sci. Eng., Ec. Polytech. Fed. Lausanne, CH-1015 Lausanne, Switz.Search for more papers by this author First published: 22 October 2015 https://doi.org/10.1002/chin.201545156Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume46, Issue45November, 2015 RelatedInformation

AbstractDepending on the choice of Rh‐catalyst and reaction solvent the directed C‐H functionalization of arylhydroxamates (I) with styrenes can be controlled to yield either 4‐ or 3‐arylated products (III) and (IV) with high regioselectivity.

Transition-metal catalyzed C-H functionalizations became a complementary and efficient bond-forming strategy over the past decade. In this respect, Cp*Rh(III) complexes have emerged as powerful catalysts for a broad spectrum of reactions giving access to synthetically versatile building blocks. Despite their high potential, the corresponding catalytic enantioselective transformations largely lag behind. The targeted transformations require all the remaining three coordination sites of the central rhodium atom of the catalyst. In consequence, the chiral information on a competent catalyst can only by stored in the cyclopentadienyl unit. The lack of suitable enabling chiral cyclopentadienyl (Cp(x)) ligands is the key hurdle preventing the development of such asymmetric versions. In this respect, an efficient set of chiral Cp(x) ligands useable with a broad variety of different transition-metals can unlock substantial application potential. This Account provides a description of our developments of two complementary classes of C2-symmetric Cp(x) derivatives. We have introduced a side- and back-wall concept to enforce chirality transfer onto the central metal atom. The first generation consists of a fused cyclohexane unit having pseudo axial methyl groups as chiral selectors and a rigidifying acetal moiety. The second ligand generation derives from an atrop-chiral biaryl-backbone and which possesses adjustable substituents at its 3,3'-positions. Both ligand families can be modulated in their respective steric bulk to adjust for the specific needs of the targeted application. The cyclopentadienes can be metalated under standard conditions. The corresponding chiral rhodium(I) ethylene complexes are relatively air and moisture and represent storable stable precatalysts for the targeted asymmetric Rh(III)-catalyzed C-H functionalizations. These complexes are then conveniently oxidized in situ by dibenzoyl peroxide to give the reactive Cp(x)Rh(III)(OBz)2 species. For instance, this catalyst is used for directed C-H activations of aryl hydroxamates and the subsequent enantioselective trapping with olefins, providing dihydroisoquinolones in very high enantioselectivities. In addition, we have established highly selective intramolecular trapping reactions with tethered higher substituted alkenes giving dihydrobenzofurans with quaternary stereogenic centers. Concerning intermolecular reactions, allene coupling partners allow for an enantioselective hydroarylation yielding substituted allylated compounds. A trapping process of the cyclometalated intermediate with diazo reactants enables the enantioselective construction of isoindolinones. Moreover, the catalysts can be used for the construction of atropchiral biaryl motives using a dehydrogenative Heck-type reaction. The development of flexibly adjustable chiral Cp(x) ligands is described in this Account showcasing their applicability for a variety of Rh(III) catalyzed C-H functionalization reactions. These Cp(x) derivatives hold promise as powerful steering ligands for further transition-metals used in asymmetric catalysis.

Rh(III) -catalyzed directed C-H functionalizations of arylhydroxamates have become a valuable synthetic tool. To date, the regioselectivity of the insertion of the unsaturated acceptor into the common cyclometalated intermediate was dependent solely on intrinsic substrate control. Herein, we report two different catalytic systems that allow the selective formation of regioisomeric 3-aryl dihydroisoquinolones and previously inaccessible 4-aryl dihydroisoquinolones under full catalyst control. The differences in the catalysts are computationally examined using density functional theory and transition state theory of different possible pathways to elucidate key contributing factors leading to the regioisomeric products. The stabilities of the initially formed rhodium complex styrene adducts, as well as activation barrier differences for the migratory insertion, were identified as key contributing factors for the regiodivergent pathways.

AbstractDiazo compounds are used as one‐carbon component in the reaction with arylhydroxamates.

Directed Cp*Rh-III-catalyzed carbon-hydrogen (C-H) bond functionalizations have evolved as a powerful strategy for the construction of heterocycles. Despite their high value, the development of related asymmetric reactions is largely lagging behind due to a limited availability of robust and tunable chiral cyclopentadienyl ligands. Rhodium complexes comprising a chiral Cp ligand with an atropchiral biaryl backbone enables an asymmetric synthesis of isoindolones from arylhydroxamates and weakly alkyl donor/acceptor diazo derivatives as one-carbon component under mild conditions. The complex guides the substrates with a high double facial selectivity yielding the chiral isoindolones in good yields and excellent enantioselectivities.