Accessing structurally diverse aryl difluoromethyl ethers with bromo(difluoro)acetic acid.

We report a new streamlined approach for the difluoromethylation of ubiquitous phenols using inexpensive bromo(difluoro)acetic acid, yielding a wide array of structurally diverse OCFH-based building blocks in a single step. This method displays broad functional group compatibility and is amenable for effective late-stage diversification and lignin-derived monomers.

Ammonia-Borane Dependent Transfer Hydrogenation of Carboxylic Esters to Primary Alcohols.

Here, we present a user-friendly protocol that uses bench-stable NH·BH (AB) as the hydrogen transfer agent for the reduction of both aromatic and aliphatic esters without an external catalyst and base, delivering a structurally diverse array of primary alcohols (80-98% yields). The broad functional-group tolerance (halogen, boronic ester, -NO, -OH, etc.) under environmentally acceptable conditions implies high practical utility.

Transfer Hydrogenation of N- and O-Containing Heterocycles Including Pyridines with HN-BH Under the Catalysis of the Homogeneous Ruthenium Precatalyst.

In this study, we report a transfer hydrogenation protocol that utilizes borane-ammonia (HN-BH) as the hydrogen source and a commercially available RuCl·HO precatalyst for the selective aromatic reduction of quinolines, quinoxalines, pyridines, pyrazines, indoles, benzofurans, and furan derivatives to form the corresponding alicyclic heterocycles in good to excellent isolated yields. Applications of this straightforward protocol include the efficient preparation of useful key pharmaceutical intermediates, such as donepezil and flumequine, including a biologically active compound.

Homogenous nickel-catalyzed chemoselective transfer hydrogenation of functionalized nitroarenes with ammonia-borane.

Homogeneous Ni-catalyzed highly selective transfer hydrogenation of nitroarenes was successfully established using NHBH as a hydrogen source. A broad range of functional groups were selectively reduced to provide the corresponding anilines in good to high yields. Further, pharmaceutically active compounds can be prepared that would otherwise be challenging to access.

Methanol as a Potential Hydrogen Source for Reduction Reactions Enabled by a Commercial Pt/C Catalyst.

Catalytic reduction reactions using methanol as a transfer hydrogenating agent is gaining significant attention because this simple alcohol is inexpensive and produced on a bulk scale. Herein, we report the catalytic utilization of methanol as a hydrogen source for the reduction of different functional organic compounds such as nitroarenes, olefins, and carbonyl compounds. The key to the success of this transformation is the use of a commercially available Pt/C catalyst, which enabled the transfer hydrogenation of a series of simple and functionalized nitroarenes-to-anilines, alkenes-to-alkanes, and aldehydes-to-alcohols using methanol as both the solvent and hydrogen donor.

Challenges and recent advancements in the transformation of CO into carboxylic acids: straightforward assembly with homogeneous 3d metals.

The transformation of carbon dioxide (CO) into useful chemicals, advanced materials, and energy is a long-standing challenge in both fundamental science and industry. In recent years, utilization of CO in the presence of inexpensive and non-negligible environmentally friendly 3d metal-based catalysts (Fe, Mn, Co, Ni, Cu and Ti) has become one of the most attractive topics. Particular attention has been given to the synthesis of carboxylic acids and their derivatives since these molecules serve as key intermediates in the chemical, fertilizer, and pharmaceutical sectors.

Lignin Residue-Derived Carbon-Supported Nanoscale Iron Catalyst for the Selective Hydrogenation of Nitroarenes and Aromatic Aldehydes.

Heterogeneous iron-based catalysts governing selectivity for the reduction of nitroarenes and aldehydes have received tremendous attention in the arena of catalysis, but relatively less success has been achieved. Herein, we report a green strategy for the facile synthesis of a lignin residue-derived carbon-supported magnetic iron (γ-FeO/LRC-700) nanocatalyst. This active nanocatalyst exhibits excellent activity and selectivity for the hydrogenation of nitroarenes to anilines, including pharmaceuticals (e.

Catalytic reductive aminations using molecular hydrogen for synthesis of different kinds of amines.

Reductive aminations constitute an important class of reactions widely applied in research laboratories and industries for the synthesis of amines as well as pharmaceuticals, agrochemicals and biomolecules. In particular, catalytic reductive aminations using molecular hydrogen are highly valued and essential for the cost-effective and sustainable production of different kinds of amines and their functionalization. These reactions couple easily accessible carbonyl compounds (aldehydes or ketones) with ammonia, amines or nitro compounds in the presence of suitable catalysts and hydrogen that enable the preparation of linear and branched primary, secondary and tertiary amines including N-methylamines and molecules used in life science applications.

Commercial Pd/C-Catalyzed -Methylation of Nitroarenes and Amines Using Methanol as Both C1 and H Source.

Herein, we report commercially available carbon-supported-palladium (Pd/C)-catalyzed -methylation of nitroarenes and amines using MeOH as both a C1 and a H source. This transformation proceeds with high atom-economy and in an environmentally friendly way via borrowing hydrogen mechanism. A total of >30 structurally diverse -methylamines, including bioactive compounds, were selectively synthesized with isolated yields of up to 95%.

Convenient iron-catalyzed reductive aminations without hydrogen for selective synthesis of N-methylamines.

N-Methylated amines play an important role in regulating the biological and pharmaceutical properties of all kinds of life science molecules. In general, this class of compounds is synthesized via reductive amination reactions using high pressure of molecular hydrogen. Thus, on laboratory scale especially in drug discovery, activated (toxic) methyl compounds such as methyl iodide and dimethyl sulfate are still employed, which also generate significant amounts of waste.

Transition-Metal-Catalyzed Utilization of Methanol as a C Source in Organic Synthesis.

Methanol is used as a common solvent, cost-effective reagent, and sustainable feedstock for value-added chemicals, pharmaceuticals, and materials. Among the various applications, the utilization of methanol as a C source for the formation of carbon-carbon, carbon-nitrogen, and carbon-oxygen bonds continues to be important in organic synthesis and drug discovery. In particular, the synthesis of C-, N-, and O-methylated products is of central interest because these motifs are found in a large number of natural products as well as fine and bulk chemicals.

Synthesis of nitriles from amines using nanoscale Co3O4-based catalysts via sustainable aerobic oxidation.

The selective oxidation of amines for the benign synthesis of nitriles under mild conditions is described. Key to success for this transformation is the application of reusable cobalt oxide-based nanocatalysts. The resulting nitriles constitute key precursors and central intermediates in organic synthesis.

Palladium-Catalyzed Trifluoromethylation of (Hetero)Arenes with CF3 Br.

The CF3 group is an omnipresent motif found in many pharmaceuticals, agrochemicals, catalysts, materials, and industrial chemicals. Despite well-established trifluoromethylation methodologies, the straightforward and selective introduction of such groups into (hetero)arenes using available and less expensive sources is still a major challenge. In this regard, the selective synthesis of various trifluoromethyl-substituted (hetero)arenes by palladium-catalyzed C-H functionalization is herein reported.

Palladium-Catalyzed Carbonylative Cyclization of Arenes by C-H Bond Activation with DMF as the Carbonyl Source.

A novel palladium-catalyzed CO-gas- and autoclave-free protocol for the synthesis of 11H-pyrido[2,1-b]quinazolin-11-ones has been developed. Quinazolinones, which are omnipresent motif in many pharmaceuticals and agrochemicals, were prepared in good yields by C-H bond activation and annulation using DMF as the CO surrogate. A (13) CO-labelled DMF control experiment demonstrated that CO gas was released from the carbonyl of DMF with acid as the promotor.

Heterogeneous platinum-catalyzed C-H perfluoroalkylation of arenes and heteroarenes.

Fluorinated organic compounds are gaining increasing interest for life science applications. The replacement of hydrogen in arenes or heteroarenes by a perfluoroalkyl group has a profound influence on the physical and biological properties of such building blocks. Here, an operationally simple protocol for the direct C-H perfluoroalkylation of (hetero)arenes with R(f)I or R(f)Br has been developed, using a robust supported platinum catalyst.

Palladium-catalyzed carbonylative reactions of 1-bromo-2-fluorobenzenes with various nucleophiles: effective combination of carbonylation and nucleophilic substitution.

A systematic study on the carbonylative transformation of 1-bromo-2-fluorobenzenes with various nucleophiles has been performed. Different types of double nucleophiles, such as NN, NC, OC, and NS, can be effectively applied as coupling partners. The corresponding six-membered heterocycles were isolated in moderate to good yields.

Palladium-catalyzed carbonylative [3+2+1] annulation of N-aryl-pyridine-2-amines with internal alkynes by C-H activation: facile synthesis of 2-quinolinones.

We describe here a novel procedure for the synthesis of highly substituted 2-quinolinones. By this newly developed approach, 2-quinolinone derivatives were prepared in moderate to good yields by carbonylative cyclization of N-aryl-pyridine-2-amines and internal alkynes by CH activation. Remarkably, [Mo(CO)6 ] was applied as a solid CO source and the reaction proceeded in an atom economic manner.

Palladium-catalyzed carbonylation of 2-bromoanilines with 2-formylbenzoic acid and 2-halobenzaldehydes: efficient synthesis of functionalized isoindolinones.

A concise and highly versatile method for the synthesis of functionalized isoindolinones is reported. Various 2-bromoanilines undergo palladium-catalyzed carbonylation with 2-formylbenzoic acid under a convenient and mild procedure to give good to excellent yields of the corresponding isoindolinones. Additionally, 2-halobenzaldehydes can be applied as substrates in palladium-catalyzed double-carbonylation to provide identical compounds in moderate to good yields.

Palladium-catalyzed carbonylations of aryl bromides using paraformaldehyde: synthesis of aldehydes and esters.

Carbonylation reactions represent useful tools for organic synthesis. However, the necessity to use gaseous carbon monoxide is a disadvantage for most organic chemists. To solve this problem, novel protocols have been developed for conducting palladium-catalyzed reductive carbonylations of aryl bromides and alkoxycarbonylations using paraformaldehyde as an external CO source (CO gas free).

Palladium-catalyzed oxidative carbonylative coupling of arylboronic acids with terminal alkynes to alkynones.

We describe here an interesting palladium-catalyzed oxidative carbonylation of arylboronic acids with terminal alkynes. By the appropriate combination of a palladium salt, a ligand, and an oxidant, the desired alkynones were isolated in moderate to good yields. Notably, all the reactions were performed at room temperature, and moisture and air can be tolerated by this procedure.

Base-controlled selectivity in the synthesis of linear and angular fused quinazolinones by a palladium-catalyzed carbonylation/nucleophilic aromatic substitution sequence.

A new approach for the facile synthesis of fused quinazolinone scaffolds through a palladium-catalyzed carbonylative coupling followed by an intramolecular nucleophilic aromatic substitution is described. The base serves as the key modulator: Whereas DBU gives rise to the linear isomers, Et3N promotes the preferential formation of angular products. Interestingly, a light-induced 4+4 reaction of the product was also observed.

Efficient palladium-catalyzed double carbonylation of o-dibromobenzenes: synthesis of thalidomide.

We describe here a convenient and mild procedure for double carbonylation of o-dibromobenzenes with various 2-amino pyridines and naturally occurring amines, thus providing in good to excellent yields N-substituted phthalimides by using this palladium-catalyzed carbonylation procedure. Furthermore, for the first time we have applied the developed synthetic protocol for the synthesis of biologically active molecule thalidomide via a single step carbonylative cyclization reaction in excellent yield.

On the role of surface composition and curvature on biointerface formation and colloidal stability of nanoparticles in a protein-rich model system.

The need for a better understanding of nanoparticle-protein interactions and the mechanisms governing the resulting colloidal stability has been emphasised in recent years. In the present contribution, the short and long term colloidal stability of silica nanoparticles (SNPs) and silica-poly(ethylene glycol) nanohybrids (Sil-PEG) have been scrutinised in a protein model system. Well-defined silica nanoparticles are rapidly covered by bovine serum albumin (BSA) and form small clusters after 20min while large agglomerates are detected after 10h depending on both particle size and nanoparticle-protein ratio.

Impact of polymer shell on the formation and time evolution of nanoparticle-protein corona.

The study of protein corona formation on nanoparticles (NPs) represents an actual main issue in colloidal, biomedical and toxicological sciences. However, little is known about the influence of polymer shells on the formation and time evolution of protein corona onto functionalized NPs. Therefore, silica-poly(ethylene glycol) core-shell nanohybrids (SNPs@PEG) with different polymer molecular weights (MW) were synthesized and exhaustively characterized.