Decarboxylative Aminomethylation of Indole-3-carboxylic Acids via Strain Release-Driven Ring Opening of 1,2-Oxazetidines.

A copper-catalyzed decarboxylative aminomethylation of indole-3-carboxylic acids with 1,2-oxazetidines has been developed, enabling the rapid synthesis of structurally diverse 3-aminomethylindoles in good to excellent yields. Remarkably, an unprecedented decarboxylative aminomethylation/cyclization cascade was further achieved by a combination of copper and iron salts to construct complex γ-carbolines with high efficiency. It is worth noting that one of the obtained products proved to be a good dual-emissive luminogen, exhibiting both aggregation-caused quenching and aggregation-induced emission.

Photochemical reductive deamination of alpha-amino aryl alkyl ketones.

Photochemical reductive deamination of alpha-amino aryl alkyl ketones under photosensitizer-free conditions is presented. This protocol features high efficiency and selectivity. A plausible reaction pathway is proposed based on ultraviolet-visible absorption investigation, control experiments and deuterium-labelling studies.

Manganese-Pincer-Catalyzed Nitrile Hydration, α-Deuteration, and α-Deuterated Amide Formation via Metal Ligand Cooperation.

A simple and efficient system for the hydration and α-deuteration of nitriles to form amides, α-deuterated nitriles, and α-deuterated amides catalyzed by a single pincer complex of the earth-abundant manganese capable of metal-ligand cooperation is reported. The reaction is selective and tolerates a wide range of functional groups, giving the corresponding amides in moderate to good yields. Changing the solvent from -butanol to toluene and using DO results in formation of α-deuterated nitriles in high selectivity.

Sterics and Hydrogen Bonding Control Stereochemistry and Self-Sorting in BINOL-Based Assemblies.

Here we demonstrate how the hydrogen-bonding ability of a BINOL-based dialdehyde subcomponent dictated the stereochemical outcome of its subsequent self-assembly into one diastereomeric helicate form when bearing free hydroxy groups, and another in the case of its methylated congener. The presence of methyl groups also altered the self-sorting behavior when mixed with another, short linear dialdehyde subcomponent, switching the outcome of the system from narcissistic to integrative self-sorting. In all cases, the axial chirality of the BINOL building block also dictated helicate metal center handedness during stereospecific self-assembly.

Synthesis of oxalamides by acceptorless dehydrogenative coupling of ethylene glycol and amines and the reverse hydrogenation catalyzed by ruthenium.

A sustainable, new synthesis of oxalamides, by acceptorless dehydrogenative coupling of ethylene glycol with amines, generating H, homogeneously catalyzed by a ruthenium pincer complex, is presented. The reverse hydrogenation reaction is also accomplished using the same catalyst. A plausible reaction mechanism is proposed based on stoichiometric reactions, NMR studies, X-ray crystallography as well as observation of plausible intermediates.

Metal-organic cages for molecular separations.

Separation technology is central to industries as diverse as petroleum, pharmaceuticals, mining and life sciences. Metal-organic cages, a class of molecular containers formed via coordination-driven self-assembly, show great promise as separation agents. Precise control of the shape, size and functionalization of cage cavities enables them to selectively bind and distinguish a wide scope of physicochemically similar substances in solution.

A Reversible Liquid-to-Liquid Organic Hydrogen Carrier System Based on Ethylene Glycol and Ethanol.

Liquid organic hydrogen carriers (LOHCs) are powerful systems for the efficient unloading and loading molecular hydrogen. Herein, a liquid-to-liquid organic hydrogen carrier system based on reversible dehydrogenative coupling of ethylene glycol (EG) with ethanol catalysed by ruthenium pincer complexes is reported. Noticeable advantages of the current LOHC system is that both reactants (hydrogen-rich components) and the produced esters (hydrogen-lean components) are liquids at room temperature, and the dehydrogenation process can be performed under solvent and base-free conditions.

Homogeneous Reforming of Aqueous Ethylene Glycol to Glycolic Acid and Pure Hydrogen Catalyzed by Pincer-Ruthenium Complexes Capable of Metal-Ligand Cooperation.

Glycolic acid is a useful and important α-hydroxy acid that has broad applications. Herein, the homogeneous ruthenium catalyzed reforming of aqueous ethylene glycol to generate glycolic acid as well as pure hydrogen gas, without concomitant CO emission, is reported. This approach provides a clean and sustainable direction to glycolic acid and hydrogen, based on inexpensive, readily available, and renewable ethylene glycol using 0.

Hydrogenative Depolymerization of Nylons.

The widespread crisis of plastic pollution demands discovery of new and sustainable approaches to degrade robust plastics such as nylons. Using a green and sustainable approach based on hydrogenation, in the presence of a ruthenium pincer catalyst at 150 °C and 70 bar H, we report here the first example of hydrogenative depolymerization of conventional, widely used nylons and polyamides, in general. Under the same catalytic conditions, we also demonstrate the hydrogenation of a polyurethane to produce diol, diamine, and methanol.

A Thioxanthone Sensitizer with a Chiral Phosphoric Acid Binding Site: Properties and Applications in Visible Light-Mediated Cycloadditions.

A chiral phosphoric acid with a 2,2'-binaphthol core was prepared that displays two thioxanthone moieties at the 3,3'-position as light-harvesting antennas. Despite its relatively low triplet energy, the phosphoric acid was found to be an efficient catalyst for the enantioselective intermolecular [2+2] photocycloaddition of β-carboxyl-substituted cyclic enones (e.r.

Recent Advances in Enantioselective Photochemical Reactions of Stabilized Diazo Compounds.

Diazo compounds have proven to be a useful class of carbenes or metal carbenoids sources under thermal, photochemical, or metal-catalyzed conditions, which can subsequently undergo a wide range of synthetically important transformations. Recently, asymmetric photocatalysis has provoked increasing research interests, and great advances have been made in this discipline towards the synthesis of optically enriched compounds. In this context, the past two decades have been the most productive period in the developments of enantioselective photochemical reactions of diazo compounds due to a better understanding of the reactivities of diazo compounds and the emergence of new catalytic modes, as well as easier access to and treatment of stabilized diazo compounds.

Ethylene Glycol as an Efficient and Reversible Liquid Organic Hydrogen Carrier.

Hydrogen has long been regarded as an ideal alternative clean energy vector to overcome the drawbacks of fossil technology. However, the direct utilization of hydrogen is challenging, due to low volumetric energy density of hydrogen gas and potential safety issues. Herein, we report an efficient and reversible liquid to liquid organic hydrogen carrier system based on inexpensive, readily available and renewable ethylene glycol.

Highly Selective, Efficient Deoxygenative Hydrogenation of Amides Catalyzed by a Manganese Pincer Complex via Metal-Ligand Cooperation.

Deoxygenative hydrogenation of amides to amines homogeneously catalyzed by a complex of an Earth-abundant metal is presented. This manganese-catalyzed reaction features high efficiency and selectivity. A plausible reaction mechanism, involving metal-ligand cooperation of the manganese pincer complex, is proposed based on NMR studies and relevant stoichiometric reactions.

Visible-Light-Induced Organic Photochemical Reactions through Energy-Transfer Pathways.

Visible-light photocatalysis is a rapidly developing and powerful strategy to initiate organic transformations, as it closely adheres to the tenants of green and sustainable chemistry. Generally, most visible-light-induced photochemical reactions occur through single-electron transfer (SET) pathways. Recently, visible-light-induced energy-transfer (EnT) reactions have received considerable attentions from the synthetic community as this strategy provides a distinct reaction pathway, and remarkable achievements have been made in this field.

Iminium and enamine catalysis in enantioselective photochemical reactions.

Although enantioselective catalysis under thermal conditions has been well established over the last few decades, the enantioselective catalysis of photochemical reactions is still a challenging task resulting from the complex enantiotopic face differentiation in the photoexcited state. Recently, remarkable achievements have been reported by a synergistic combination of organocatalysis and photocatalysis, which have led to the expedient construction of a diverse range of enantioenriched molecules which are generally not easily accessible under thermal conditions. In this tutorial review, we summarize and highlight the most significant advances in iminium and enamine catalysis of enantioselective photochemical reactions, with an emphasis on catalytic modes and reaction types.

Recent Advances in the Synthesis of Cyclobutanes by Olefin [2 + 2] Photocycloaddition Reactions.

The [2 + 2] photocycloaddition is undisputedly the most important and most frequently used photochemical reaction. In this review, it is attempted to cover all recent aspects of [2 + 2] photocycloaddition chemistry with an emphasis on synthetically relevant, regio-, and stereoselective reactions. The review aims to comprehensively discuss relevant work, which was done in the field in the last 20 years (i.

Phototandem catalysis: efficient synthesis of 3-ester-3-hydroxy-2-oxindoles by a visible light-induced cyclization of diazoamides through an aerobic oxidation sequence.

An unprecedented phototandem catalysis based on a single iridium photocatalyst has been successfully developed. This powerful strategy consists of two mechanistically distinct catalytic cycles, namely, photocatalytic energy transfer (ET) and single electron transfer (SET). The novel protocol allows a rapid and efficient construction of biologically and synthetically important 3-ester-3-hydroxy-2-oxindole derivatives from readily available diazoamides through a cyclization/aerobic oxidation sequence under very mild conditions.

Three-component coupling reaction triggered by insertion of arynes into the S═O bond of DMSO.

An unprecedented three-component coupling reaction of arynes, α-bromo carbonyl compounds, and DMSO triggered by insertion of arynes into the S═O bond of DMSO has been developed. The reaction can generate a wide range of multisubstituted aryl methyl thioethers in good yields, wherein DMSO serves as both methylthiolation reagent and oxygen source.

De novo synthesis of imidazoles by visible-light-induced photocatalytic aerobic oxidation/[3+2] cycloaddition/aromatization cascade.

A visible-light-induced photocatalytic aerobic oxidation/[3+2] cycloaddition/aromatization cascade between secondary amines and isocyanides has been successfully developed. The reaction provides a general and efficient access to diversely substituted imidazoles and imidazo[1,5-a]quinoxalin-4(5 H)-ones in good yields under mild conditions.

Direct sp(3)C-H acroleination of N-aryl-tetrahydroisoquinolines by merging photoredox catalysis with nucleophilic catalysis.

Sequence catalysis merging photoredox catalysis (PC) and nucleophilic catalysis (NC) has been realized for the direct sp(3) C-H acroleination of N-aryl-tetrahydroisoquinoline (THIQ). The reaction was performed under very mild conditions and afforded products in 50-91% yields. A catalytic asymmetric variant was proved to be successful with moderate enantioselectivities (up to 83 : 17 er).

An organocatalytic Michael-aldol cascade: formal [3+2] annulation to construct enantioenriched spirocyclic oxindole derivatives.

An efficient organocatalytic Michael-aldol cascade reaction for the asymmetric synthesis of spirocyclic oxindole derivatives fused with tetrahydrothiophenes has been developed through a formal [3+2] annulation strategy.