Progress in hydroformylation and carbonylation

From Alkynes to Heterocycles through Metal-Promoted Silylformylation and Silylcarbocyclization Reactions

Oxygen and nitrogen heterocyclic systems are present in a large number of natural and synthetic compounds. In particular, oxa- and aza-silacyclane, tetrahydrofuran, benzofuran, cycloheptadifuranone, cycloheptadipyrrolone, pyrrolidine, lactone, lactam, phthalan, isochromanone, tetrahydroisoquinolinone, benzoindolizidinone, indoline and indolizidine scaffolds are present in many classes of biologically active molecules. Most of these contain a C=O moiety which can be easily introduced using carbonylative reaction conditions. In this field, intramolecular silylformylation and silylcarbocyclization reactions may afford heterocyclic compounds containing a carbonyl functional group together with a vinylsilane moiety which can be further transformed. Considering these two aspects, in this review a detailed analysis of the literature data regarding the application of silylformylation and silylcarbocyclization reactions to the synthesis of several heterocyclic derivatives is reported.

Application of Coordination Compounds with Transition Metal Ions in the Chemical Industry-A Review

This publication presents the new trends and opportunities for further development of coordination compounds used in the chemical industry. The review describes the influence of various physicochemical factors regarding the coordination relationship (for example, steric hindrance, electron density, complex geometry, ligand), which condition technological processes. Coordination compounds are catalysts in technological processes used during organic synthesis, for example: Oxidation reactions, hydroformylation process, hydrogenation reaction, hydrocyanation process. In this article, we pointed out the possibilities of using complex compounds in catalysis, and we noticed what further research should be undertaken for this purpose.

Synthesis and Reactivity of Organometallic Intermediates Relevant to Cobalt-Catalyzed Hydroformylation

Intermediates relevant to cobalt-catalyzed alkene hydroformylation have been isolated and evaluated in fundamental organometallic transformations relevant to aldehyde formation. The 18-electron (R,R)-(^iPr DuPhos)Co(CO)₂ H has been structurally characterized, and it promotes exclusive hydrogenation of styrene in the presence of 50 bar of H₂ /CO gas (1:1) at 100 °C. Deuterium-labeling studies established reversible 2,1-insertion of styrene into the Co-D bond of (R,R)-(^iPr DuPhos)Co(CO)₂ D. Whereas rapid β-hydrogen elimination from cobalt alkyls occurred under an N₂ atmosphere, alkylation of (R,R)-(^iPr DuPhos)Co(CO)₂ Cl in the presence of CO enabled the interception of (R,R)-(^iPr DuPhos)Co(CO)₂ C(O)CH₂ CH₂ Ph, which upon hydrogenolysis under 4 atm H₂ produced the corresponding aldehyde and cobalt hydride, demonstrating the feasibility of elementary steps in hydroformylation. Both the hydride and chloride derivatives, (X=H^- , Cl^- ), underwent exchange with free ¹³ CO. Under reduced pressure, (R,R)-(^iPr DuPhos)Co(CO)₂ Cl underwent CO dissociation to form (R,R)-(^iPr DuPhos)Co(CO)Cl.

Catalytic Reductive Aldol and Mannich Reactions of Enone, Acrylate, and Vinyl Heteroaromatic Pronucleophiles

Catalytic reductive coupling of enone, acrylate, or vinyl heteroaromatic pronucleophiles with carbonyl or imine partners offers an alternative to base-mediated enolization in aldol- and Mannich-type reactions. In this review, direct catalytic reductive aldol and Mannich reactions are exhaustively catalogued on the basis of metal or organocatalyst. Stepwise processes involving enone conjugate reduction to form discrete enol or (metallo)enolate derivatives followed by introduction of carbonyl or imine electrophiles and aldol reactions initiated via enone conjugate addition are not covered.

Allothermal Gasification of Peat and Lignite by a Focused Light Flow

Gasification of peat and lignite under a focused light flow was observed in a wide range of fuel moisture (up to 65 wt.%). The initial water content in the fuels under study had a different influence on the chemical composition of the synthesis gas (syngas). At the same time, the effect of light intensity was more predictable: in general, the production of gases grew with it. It was shown that the gasification of peat accelerated greatly when light intensity exceeded 100 W/cm2. Moreover, the conversion of peat and lignite required an order of magnitude lower intensity of the light flow than was necessary for the conversion of bituminous coal processing waste. The dynamics of the sample weight changes demonstrated that contrary to bituminous coals, the process was not purely allothermal for both peat and lignite. However, the fuel smoldering was not self-sustainable and stopped shortly after the pumping light was turned off.

Nickel-catalyzed carboxylation of aryl iodides with lithium formate through catalytic CO recycling

A protocol for the Ni-catalyzed carboxylation of aryl iodides with formate has been developed with good functional group compatibility for the synthesis of a variety of aromatic carboxylic acids under mild conditions. The reaction tolerates other functionalities for cross-coupling, such as aryl bromide, aryl chloride, aryl tosylate, and aryl pinacol boronate. The reaction proceeds through a carbonylation process with in situ generated carbon monoxide in the presence of a catalytic amount of acetic anhydride and lithium formate, avoiding the use of gaseous CO. The strategy of CO recycling in catalytic amounts is critical for the success of the reaction.

Highly uniform Rh nanoparticles supported on boron doped g-C3N4 as a highly efficient and recyclable catalyst for heterogeneous hydroformylation of alkenes

A highly efficient and recyclable Rh/B-g-C₃N₄ catalyst was firstly applied in hydroformylation of alkenes.

A general platinum-catalyzed alkoxycarbonylation of olefins

Herein, we report the first efficient platinum-catalysed alkoxycarbonylations of olefins including sterically hindered and functionalized ones. This atom-efficient catalytic transformation provides straightforward access to a variety of valuable esters.

Octahedral gold-silver nanoframes with rich crystalline defects for efficient methanol oxidation manifesting a CO-promoting effect

Three-dimensional bimetallic nanoframes with high spatial diffusivity and surface heterogeneity possess remarkable catalytic activities owing to their highly exposed active surfaces and tunable electronic structure. Here we report a general one-pot strategy to prepare ultrathin octahedral Au₃Ag nanoframes, with the formation mechanism explicitly elucidated through well-monitored temporal nanostructure evolution. Rich crystalline defects lead to lowered atomic coordination and varied electronic states of the metal atoms as evidenced by extensive structural characterizations. When used for electrocatalytic methanol oxidation, the Au₃Ag nanoframes demonstrate superior performance with a high specific activity of 3.38 mA cm⁻², 3.9 times that of the commercial Pt/C. More intriguingly, the kinetics of methanol oxidation on the Au₃Ag nanoframes is counter-intuitively promoted by carbon monoxide. The enhancement is ascribed to the altered reaction pathway and enhanced OH⁻ co-adsorption on the defect-rich surfaces, which can be well understood from the d-band model and comprehensive density functional theory simulations.

Direct methanol fuel cells are promising for clean, sustainable energy, but catalysts should be optimized. Here the authors construct ultrathin nanoframes with rich crystalline defects to increase electrocatalytic activity of gold for methanol oxidation, which is surprisingly promoted by carbon monoxide.

Palladium-Catalyzed Enantioselective Thiocarbonylation of Styrenes

A highly enantioselective thiocarbonylation of styrenes with CO and thiols has been achieved by Pd catalysis, providing highly enantioenriched thioesters in good to excellent yields. Key to the successful execution of this reaction is the use of a chiral sulfoxide-(P-dialkyl)-phosphine (SOP) ligands. This thiocarbonylation proceeds smoothly under mild reaction conditions (1 atm CO and 0 °C) and displays broad substrate scope. Also demonstrated is that this transformation can be conducted using surrogates of CO, greatly increasing the safety aspects of running the reaction. The generality and utility of the method is manifested by its application to the synthetic transformations of thioester products and the direct acylation of cysteine-containing dipeptides. A primary mechanism was investigated and a plausible catalytic cycle was proposed.

Highly Regioselective Hydroformylation of Higher Olefins Catalysed by Rhodium-phosphine Complexes in Ionic Liquid Medium

Hydroformylation of higher olefins was performed efficiently in ionic liquids 1-n-alkyl-3-methylimidazolium p-toluenesulfonate ([Rmim][p-CH3C6H4SO3], R = n-butyl, n-octyl, n-dodecyl, n-cetyl) with the rhodium-phosphine complex Rh-BISBIS (Rh = rhodium complex catalyst precursor; BISBIS = sodium salt of sulfonated 2,2′-bis (diphenylphosphinomethyl)-1,1′-biphenyl) as catalyst. The catalytic system offers excellent regioselectivity towards the linear aldehyde with high activity and chemoselectivity for aldehyde. Furthermore, the ionic liquid containing catalyst can be facilely separated and reused three times without a significant decrease in the activity and selectivity. The ionic liquids [Rmim][p-CH3C6H4SO3] used as the reaction media bring some definitive advantages over the halogen-containing analogues [bmim]BF4 and [bmim]PF6.

Coordinated “Naked” Pnicogenes and Catalysis

Diphosphorous (P2) side-on coordinated to a dicobalt (Co–Co) moiety was described 45 years ago. This discovery had several links to actual problems of homogeneous molecular catalysis. The new type of organometallic complexes induced several ingenious new ramifications in main-group/transition metal cluster chemistry in the last decades. The present review traces the main lines of these research results and their contacts to actual problems of industrial catalysis.

Carbon Monoxide as a Promoter of Atomically Dispersed Platinum Catalyst in Electrochemical Hydrogen Evolution Reaction

Carbon monoxide is widely known to poison Pt during heterogeneous catalysis owing to its strong donor-acceptor binding ability. Herein, we report a counterintuitive phenomenon of this general paradigm when the size of Pt decreases to an atomic level, namely, the CO-promoting Pt electrocatalysis toward hydrogen evolution reactions (HER). Compared to pristine atomic Pt catalyst, reduction current on a CO-modified catalyst increases significantly. Operando mass spectroscopy and electrochemical analyses demonstrate that the increased current arises due to enhanced H₂ evolution, not additional CO reduction. Through structural identification of catalytic sites and computational analysis, we conclude that CO-ligation on the atomic Pt facilitates H_ads formation via water dissociation. This counterintuitive effect exemplifies the fully distinct characteristics of atomic Pt catalysts from those of bulk Pt, and offers new insights for tuning the activity of similar classes of catalysts.

Development of efficient palladium catalysts for alkoxycarbonylation of alkenes

Herein, we report a general and efficient Pd-catalysed alkoxycarbonylation of sterically hindered and demanding olefins including a variety of tri-, tetra-substituted and 1,1-disubstituted alkenes. In the presence of 1,3-bis(tert-butyl(pyridin-2-yl)phosphanyl)propane L3 or 1,4-bis(tert-butyl(pyridin-2-yl)phosphanyl)butane L4 the desired esters are obtained in good yields and selectivities. Similar transformation is obtained using tertiary ether as showcased in the carbonylation of MTBE to the corresponding linear ester in high yield and selectivity.

Single-atom catalyst: a rising star for green synthesis of fine chemicals

The green synthesis of fine chemicals calls for a new generation of efficient and robust catalysts. Single-atom catalysts (SACs), in which all metal species are atomically dispersed on a solid support, and which often consist of well-defined mononuclear active sites, are expected to bridge homogeneous and heterogeneous catalysts for liquid-phase organic transformations. This review summarizes major advances in the SAC-catalysed green synthesis of fine chemicals in the past several years, with a focus on the catalytic activity, selectivity and reusability of SACs in various organic reactions. The relationship between catalytic performance and the active site structure is discussed in terms of the valence state, coordination environment and anchoring chemistry of single atoms to the support, in an effort to guide the rational design of SACs in this special area, which has traditionally been dominated by homogeneous catalysis. Finally, the challenges remaining in this research area are discussed and possible future research directions are proposed.

Diverse bimetallic mechanisms emerging from transition metal Lewis acid/base pairs: development of co-catalysis with metal carbenes and metal carbonyl anions

The rational development of catalytic reactions involving cooperative behavior between two catalytic reactive sites represents a frontier area of research from which novel reactivity and selectivity patterns emerge.

SO2 F2 -Mediated One-Pot Synthesis of Aryl Carboxylic Acids and Esters from Phenols through a Pd-Catalyzed Insertion of Carbon Monoxide

A one-pot Pd-catalyzed carbonylation of phenols into their corresponding aryl carboxylic acids and esters through the insertion of carbon monoxide has been developed. This procedure offers a direct synthesis of aryl carboxylic acids and esters from inexpensive and abundant starting materials (phenols, SO₂ F₂ and CO) under mild conditions. This method tolerates a broad range of functional groups and is also applicable for the modification of complicated natural products.

Heterogeneous One-Pot Carbonylation and Mizoroki-Heck Reaction in a Parallel Manner Following the Cleavage of Cinnamaldehyde Derivatives

Carbon monoxide (CO) and styrene derivatives that can be both generated by a palladium on carbon (Pd/C)-catalyzed carbon-carbon (C-C) bond cleavage reaction of cinnamaldehyde derivatives were effectively utilized in further palladium-catalyzed C-C bond forming reactions in a direct and practical way. CO derived from simple and affordable CO carriers such as cinnamaldehyde or terephthalaldehyde was efficiently employed in the in situ CO fixation with various aromatic iodides through a palladium-catalyzed carbonylation followed by an inter- or intramolecular coupling reaction with alcohols to afford the corresponding esters or lactones, respectively. Styrene derivatives were also efficient substrates in an in situ Mizoroki-Heck-type cross-coupling reaction with aryl iodides, leading to the effective formation of asymmetric stilbenes. The decarbonylation of cinnamaldehyde derivatives and the subsequent independent syntheses of both esters/lactones and 1,2-diarylethenes could be achieved in a virtual one-pot and in situ reaction using a H-shaped pressure-tight glass-sealed tube consisting of two independent but laterally connected reaction tubes in the gas space.