Designing a visible light-mediated double photoswitch: a combination of biradical and azobenzene structural motifs that can be switched independently.

A new molecular switch is presented that combines both biradical and azobenzene motifs to perform visible light-induced constitutional and stereo-isomerisation within the same molecule. The insertion of isonitrile-functionalised azobenzenes into the four-membered biradical [˙P(μ-NTer)P˙] (1), yielding a phosphorus-centred cyclopentane-1,3-diyl (-4B and -5B), represents a straightforward method to generate the desired double switches (-4B and -5B) in excellent yields (>90%). The switching properties are demonstrated for the fluorinated species -5B and, interestingly, can occur either stepwise or simultaneously, depending on the order in which the sample is irradiated with red and/or green light.

Amino Acid-Based Ionic Liquids-Aided CO Hydrogenation to Methanol.

This study explored the use of amino acid-based ionic liquids to facilitate the conversion of carbon dioxide (CO) into methanol through catalytic hydrogenation. Combining tetrabutylammonium L-argininate (TBA⋅Arg) with the ruthenium Ru-MACHO-BH complex allowed achieving significant yields of methanol under optimized conditions, with a turnover number (TON) up to 700. By systematically varying key reaction parameters, we demonstrated that the TBA⋅Arg ionic liquid promotes the efficient hydrogenation pathway leading to methanol formation, thus offering a sustainable approach to CO valorization.

Red-light-mediated copper-catalyzed photoredox catalysis promotes regioselectivity switch in the difunctionalization of alkenes.

Controlling regioselectivity during difunctionalization of alkenes remains a significant challenge, particularly when the installation of both functional groups involves radical processes. In this aspect, methodologies to install trifluoromethane (-CF) via difunctionalization have been explored, due to the importance of this moiety in the pharmaceutical sectors; however, these existing reports are limited, most of which affording only the corresponding β-trifluoromethylated products. The main reason for this limitation arises from the fact that -CF group served as an initiator in those reactions and predominantly preferred to be installed at the terminal (β) position of an alkene.

Domino reactions of chromones with activated carbonyl compounds.

Domino reactions of chromones with activated carbonyl compounds, such as dimethyl acetone-1,3-dicarboxylate and 1,3-diphenylacetone, and with 1,3-bis(silyloxy)-1,3-butadienes, electroneutral equivalents of 1,3-dicarbonyl dianions, allow for a convenient synthesis of a great variety of products. The regioselectivity and course of the reaction depends of the substituent located at carbon C3 of the chromone moiety and also on the type of nucleophile employed.

Synthesis and optical properties of bis- and tris-alkynyl-2-trifluoromethylquinolines.

Three bis- or tris-brominated 2-trifluoromethylquinolines have been successfully applied in palladium-catalysed Sonogashira reactions, leading to several examples of alkynylated quinolines in good to excellent yields. Optical properties of selected products have been studied by steady state absorption and fluorescence spectroscopy which give insights of the influence of the substitution pattern and of the type of substituents on the optical properties.

Regiodivergent Carbonylation of Alkenes: Selective Palladium-Catalyzed Synthesis of Linear and Branched Selenoesters.

An unprecedented regiodivergent palladium-catalyzed carbonylation of aromatic alkenes has been developed. Utilizing commercially available Pd(CH CN) Cl in the presence of 1,1'-ferrocenediyl-bis(tert-butyl(pyridin-2-yl)phosphine) ligand L8 diverse selenoesters are obtained in a straightforward manner. Key to success for the control of the regioselectivity of the carbonylation step is the concentration of the acidic co-catalyst.

Synthesis of Benzene Derivatives with Multiple Dichlorophosphino Groups.

The chlorination of 1,2-diphosphinobenzene with PCl to 1,2-bis(dichlorophosphino)benzene was performed with high yields (93 %) despite the high number of P-H functions. The method was further applied to other phosphanes, enabling the first synthesis and complete characterization of 1,2,4-tris(dichlorophosphino)benzene (89 % yield) and 1,2,4,5-tetrakis(dichlorophosphino)benzene (91 % yield), valuable precursors for example for binuclear complexes, coordination polymers, organic wires, or metal-organic frameworks. The application of the chlorophosphanes in base induced ring closure reactions with primary amines is demonstrated.

Access to Benzo- and Naphtho-Azaphospholes via C-H Bond Activation of Aryl-Substituted Isonitriles.

Differently substituted phenyl isonitriles (with C-H bonds in ortho-position) and naphthyl isonitriles were reacted with the cyclic biradical [⋅P(μ-N-Ter) P⋅] (1). Insertion of the isonitrile formed a cyclic five-membered biradical [⋅P(NTer) C(R)P⋅] (2R, R=phenyl, naphthyl) in the first step, followed by C-H activation at the aryl substituent, resulting in novel azaphospholes (5R), which could be isolated and fully characterized. The formation of the azaphospholes can be prevented by the addition of a second equivalent of isonitrile, which causes the blocking of the radical centers in 2R by adduct formation (3R).

Integrating Bifunctionality and Chemical Stability in Covalent Organic Frameworks via One-Pot Multicomponent Reactions for Solar-Driven HO Production.

Multicomponent reactions (MCRs) can be used to introduce different functionalities into highly stable covalent organic frameworks (COFs). In this work, the irreversible three-component Doebner reaction is utilized to synthesize four chemically stable quinoline-4-carboxylic acid DMCR-COFs ( and ) equipped with an acid-base bifunctionality. These DMCR-COFs show superior photocatalytic HO evolution (one of the most important industrial oxidants) compared to the imine COF analogue ().

In Situ-Generated Cu Catalytic System for Oxidative N-Formylation of N-Heterocycles and Acyclic Amines with Methanol.

The development of a sustainable and simple catalytic system for N-formylation of N-heterocycles with methanol by direct coupling remains a challenge, owing to many competing side reactions, given the sensitivity of N-heterocycles to many catalytic oxidation or dehydrogenation systems. This work concerns the development of an in situ-generated Cu catalytic system for oxidative N-formylation of N-heterocycles with methanol that is based on the case study of a more typical 1,2,3,4-tetrahydroquinoline as substrate. Aside from N-heterocycles, some acyclic amines are also transformed into the corresponding N-formamides in moderate yields.

Low-Temperature Isolation of a Labile Silylated Hydrazinium-yl Radical Cation, [(Me Si) N-N(H)SiMe ].

The oxidation of silylated hydrazine, (Me Si) N-N(H)SiMe , with silver salts led to the formation of a highly labile hydrazinium-yl radical cation, [(Me Si) N-N(H)SiMe ] , at very low temperatures (decomposition > -40 °C). EPR, NMR, DFT and Raman studies revealed the formation of a nitrogen-centered radical cation along the N-N unit of the hydrazine. In the presence of the weakly coordinating anion [Al{OCH(CF ) } ] , crystallization and structural characterization in the solid state were achieved.

A Persistent Phosphanyl-Substituted Thioketyl Radical Anion.

Alkali metal salts, M [Ter(iPr)P-C(=S)-P(iPr) S] (M=Na, K; 2_M; Ter=2,6-bis-(2,4,6-trimethylphenyl)phenyl) containing a room-temperature-stable thioketyl radical anion were obtained by reduction of the thioketone precursor, Ter(iPr)P-C(=S)-P(iPr) S (1), with alkali metals (Na, K). Single-crystal X-ray studies as well as EPR spectroscopy revealed the unequivocal existence of a thioketyl radical anion in the solid state and in solution, respectively. The computed Mulliken spin density within 2_M is mainly located at the sulfur (49 %) and the carbonyl carbon (33 %) atoms.

Dihydroxyacetone valorization with high atom efficiency via controlling radical oxidation pathways over natural mineral-inspired catalyst.

Diminishing fossil fuel resources and calls for sustainability are driving the urgent need for efficient valorization of renewable resources with high atom efficiency. Inspired from the natural goethite mineral with Mn paragenesis, we develop cost-effective MnO/goethite catalysts for the efficient valorization of dihydroxyacetone, an important biomass-based platform molecule, into value-added glycolic acid and formic acid with 83.2% and 93.

Reaction of potassium phosphide KP(iPr)Ter with chalcogens, heteroallenes and an acyl chloride.

The reactivity of the secondary phosphide KP(Pr)Ter (1) (Ter = 2,6-bis-(2,4,6-trimethylphenyl)phenyl) toward small molecules is reported. Phosphide 1 displays distinct nucleophilic character and reacts selectively with chalcogens (S, Se), heteroallenes (CO, PrNCS), and an acyl chloride (AdCOCl) to give the corresponding dichalcogenophosphinates (2a, 3), phosphanyl formate (5), thiocarbamoylphosphane (6a), or acylphosphane (7a), respectively. Furthermore the follow-up chemistry of these products was investigated.

Synthesis and investigation on optical and electrochemical properties of 2,4-diaryl-9-chloro-5,6,7,8-tetrahydroacridines.

A facile synthesis of 2,4-diaryl-9-chloro-5,6,7,8-tetrahydroacridine derivatives is reported which is based on POCl-mediated cyclodehydration followed by double Suzuki-Miyaura cross-coupling. The absorption and fluorescence properties of the obtained products were investigated and their HOMO/LUMO energy levels were estimated by cyclic voltammetry measurements. Besides, density functional theory calculations were carried out for further exploration of their electronic properties.

Palladium-Catalyzed Domino Aminocarbonylation of Alkynols: Direct and Selective Synthesis of Itaconimides.

The first direct and selective synthesis of substituted itaconimdes by palladium-catalyzed aminocarbonylation of alkynols is reported. Key to the success of this transformation is the use of a novel catalyst system involving ligand and appropriate reaction conditions. In the protocol here presented, easily available propargylic alcohols react with -nucleophiles including aryl- and alkylamines as well as aryl hydrazines to provide a broad variety of interesting heterocycles with high catalyst activity and excellent selectivity.

Pd/Cu-Catalyzed amide-enabled selectivity-reversed borocarbonylation of unactivated alkenes.

The addition reaction between CuBpin and alkenes to give a terminal boron substituted intermediate is usually fast and facile. In this communication, a selectivity-reversed procedure has been designed and established. This selectivity-reversed borocarbonylation reaction is enabled by a cooperative action between palladium and copper catalysts and proceeds with complete regioselectivity.

2,4-Bis(arylethynyl)-9-chloro-5,6,7,8-tetrahydroacridines: synthesis and photophysical properties.

Acridine derivatives have attracted considerable interest in numerous areas owing to their attractive physical and chemical properties. Herein, starting from readily available anthranilic acid, an efficient synthesis of 2,4-bis(arylethynyl)-9-chloro-5,6,7,8-tetrahydroacridine derivatives was accomplished via a one-pot double Sonogashira cross-coupling method. The UV-visible absorption and emission properties of the synthesized molecules have been examined.

The cascade coupling/iodoaminocyclization reaction of trifluoroacetimidoyl chlorides and allylamines: metal-free access to 2-trifluoromethyl-imidazolines.

A metal-free cascade coupling/iodoaminocyclization reaction for the rapid assembly of 2-trifluoromethyl-imidazolines has been disclosed. The transformation applies readily accessible trifluoroacetimidoyl chlorides, allylamines and N-iodosuccinimides as the starting substrates, achieving an efficient and straightforward pathway to construct diverse imidazoline derivatives. Excellent efficiency of the reaction is observed (higher than 90% isolated yield for half of the examples), and the obtained imidazoline products bearing a pendent iodomethyl group could be easily transformed into other synthetically valuable compounds.

Supported Palladium-Catalyzed Carbonylative Synthesis of Diaryl Ketones from Aryl Bromides and Arylboronic Acids.

A palladium supported on graphitic carbon nitride (Pd/g-C N ) catalyzed carbonylative reaction of aryl bromides and arylboronic acids by has been developed for the construction of diaryl ketones. Using benzene-1,3,5-triyl triformate (TFBen) as the CO source, the reaction proceeded well to give various diaryl ketones in moderate to good yields.

Ligand-Controlled Regiodivergent Thiocarbonylation of Alkynes toward Linear and Branched α,β-Unsaturated Thioesters.

Thiocarbonylation of alkynes offers an ideal procedure for the synthesis of unsaturated thioesters. A robust ligand-controlled regioselective thiocarbonylation of alkynes is developed. Utilizing boronic acid and 5-chlorosalicylic acid as the acid additive to in situ form 5-chloroborosalicylic acid (5-Cl-BSA), and bis(2-diphenylphosphinophenyl)ether (DPEphos) as the ligand, linear α,β-unsaturated thioesters were produced in a straightforward manner.

Protonated Imine-Linked Covalent Organic Frameworks for Photocatalytic Hydrogen Evolution.

Covalent organic frameworks (COFs) have emerged as an important class of organic semiconductors and photocatalysts for the hydrogen evolution reaction (HER)from water. To optimize their photocatalytic activity, typically the organic moieties constituting the frameworks are considered and the most suitable combinations of them are searched for. However, the effect of the covalent linkage between these moieties on the photocatalytic performance has rarely been studied.

Inorganic electrides of alkali metal doped ZnO nanocage with excellent nonlinear optical response.

Finding new materials with exceptionally large nonlinear optical response is an interesting and challenging avenue for scientific research. Here, we report the alkali metal doped ZnO nanocages as inorganic electrides with excellent nonlinear optical response. Density functional theory calculations have been performed for geometric, electronic and nonlinear optical response of exo- and endohedrally alkali metal doped ZnO nanoclusters.

Copper-Catalyzed Borylative Methylation of Alkyl Iodides with CO as the C1 Source: Advantaged by Faster Reaction of CuH over CuBpin.

CuH and CuBpin are versatile catalysts and intermediates in organic chemistry. However, studies that involve both CuH and CuBpin in the same reaction is still rarely reported due to their high reactivity. Now, a study on CuH- and CuBpin-catalyzed borylative methylation of alkyl iodides with CO as the C1 source is reported.

Synthesis of 3-1,2,4-Triazol-3-ones via NiCl-Promoted Cascade Annulation of Hydrazonoyl Chlorides and Sodium Cyanate.

A nickel-promoted cascade annulation reaction for the facile synthesis of 3-1,2,4-triazol-3-ones from readily available hydrazonoyl chlorides and sodium cyanate has been developed. The transformation occurs through a cascade nickel-promoted intermolecular nucleophilic addition-elimination process, intramolecular nucleophilic addition, and a hydrogen-transfer sequence. The method has been successfully applied for the construction of the core skeleton of the angiotensin II antagonist.