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Dialkoxymethane (DAM) ethers, so‐called oxymethylene ethers (OMEs), are compounds constituted by a CH2‐unit bound to two identical alkoxy substituents. These compounds have showcased interesting technological applications as fuel additives or fuels, as a consequence of their interesting properties such as their low vapor pressure, high viscosity, cetane number and oxygen content. Moreover, they are also employed as environmentally‐benign solvents and bulk compounds useful in fine‐chemical industry. In addition, DAM ethers are considered formaldehyde surrogates. Industrially, dimethoxymethane (DMM) is still produced via two‐step protocol involving toxic formaldehyde that consists of a first step of methanol oxidation (Formox process). Hence, the development of more sustainable protocols for their synthesis is highly desired. Among the different strategies reported for DAM synthesis, its production from CO2/H2 and alcohols constitutes a practical, green and attractive alternative route. In this concept, a careful discussion of the developed catalytic protocols for synthesizing DAM from CO2/H2 or formic acid/H2 and alcohols/diols will be summarized. A special emphasis will be performed on the reaction mechanisms involved and the catalyst nature design and characterization. [ABSTRACT FROM AUTHOR]

An efficient heterogeneous catalytic system for the oxidative aminocarbonylation of alkynes and amines in the presence of CO/O2 to afford substituted propiolamides has been developed. The active nanocatalyst, [Pd/Mg3Al‐LDH]‐300(D), is composed by Pd nanoaggregates (2–3 nm average particle size) stabilized over a partially dehydrated [Mg3Al‐LDH] matrix. The methodology has resulted widely applicable, being the first catalytic system, either homogeneous or heterogeneous, able to activate not only aliphatic amines but also poorly‐nucleophilic aromatic amines. In fact, >60 substituted propiolamides have been synthesized in good to excellent isolated yields through this methodology, being 27 novel compounds. An important characterization effort (XRD, 27Al MAS NMR, TGA, TPD‐CO2, BET area, XPS, HAADF‐HRSTEM and HRTEM) and optimization of the synthesis conditions of the optimal catalyst has been performed. This study, together with a series of kinetic and mechanistic essays, indicates that the optimal catalyst is composed by Pd(0) species stabilized in a partially dehydrated/dehydroxylated LDH material with a Mg/Al molar ratio of 3 and a small crystallite size. All the experimental data indicates that the in situ formation of [PdI2] active species in the material surface together with the presence of a matrix with the optimal acid/base properties are key aspects of this process. [ABSTRACT FROM AUTHOR]

An efficient heterogeneous silver‐catalyzed α‐alkylation of nitriles and oxindoles using alcohols via borrowing hydrogen strategy has been developed for the first time. The active nanostructured material, namely [Ag/Mg4Al‐LDH], composed by silver nanoparticles (3‐4 nm average particle size) homogeneously stabilized onto a [Mg4Al‐LDH] support with suitable Brønsted basic properties, constitutes a stable catalyst for the sustainable building of novel C−C bonds from alcohols and C‐nucleophiles. By applying this catalyst, a broad range of α‐functionalized nitriles and oxindoles has been accessed with good to excellent isolated yields and without the addition of external bases. Moreover, the novel silver nanocatalyst has also demonstrated its successful application to the cyclization of N‐[2‐(hydroxymethyl)phenyl]‐2‐phenylacetamides to afford 3‐arylquinolin‐2(1H)‐ones, through a one‐pot dehydrogenation and intramolecular α‐alkylation. Control experiments, kinetic studies, and characterization data of a variety of [Ag/LDH]‐type materials confirmed the silver role in the dehydrogenation and hydrogenation steps, while [Mg4Al‐LDH] matrix is able to catalyze condensation. Interestingly, these studies suggest as key point for the successful activity of [Ag/Mg4Al‐LDH], in comparison with other [Ag/LDH]‐type nanocatalysts, the suitable acid‐base properties of this material. [ABSTRACT FROM AUTHOR]

Ether derivatives have myriad applications in several areas of chemical industry and academia. Hence, the development of more effective and sustainable protocols for their production is highly desired. Among the different methodologies reported for ether synthesis, catalytic reductive alcohol etherifications with carbonyl‐based moieties (aldehydes/ketones and carboxylic acid derivatives) have emerged in the last years as a potential tool. These processes constitute appealing routes for the selective production of both symmetrical and asymmetrical ethers (including O‐heterocycles) with an increased molecular complexity. Likewise, ester‐to‐ether catalytic reductions and hydrogenative alcohol etherifications with CO2 to dialkoxymethanes and other acetals, albeit in less extent, have undergone important advances, too. In this Review, an update of the recent progresses in the area of catalytic reductive alcohol etherifications using carbonyl‐based compounds and CO2 have been described with a special focus on organic synthetic applications and catalyst design. Complementarily, recent progress made in catalytic acetal/ketal‐to‐ether or ester‐to‐ether reductions and other related transformations have been also summarized. [ABSTRACT FROM AUTHOR]

The article titled "Cover Feature: A General and Highly Versatile Heterogeneous Pd-Catalyzed Oxidative Aminocarbonylation of Alkynes with Aromatic and Aliphatic Amines" discusses a catalytic system that has been developed for the oxidative aminocarbonylation of amines and alkynes. The system utilizes a nanocatalyst composed of palladium nanoparticles supported on a partially dehydrated and dehydroxylated LDH matrix. This nanocatalyst is able to activate poorly nucleophilic aromatic amines, resulting in the production of N-arylpropiolamides. The research article provides more detailed information on this topic. [Extracted from the article]

The synthesis of [alpha],[alpha]' ,N-Triarylbisenamines based on an unprecedented gold(I)-catalyzed double intermolecular hydroamination between N-arylamines and aryl alkynes is described. The study provides insight into the property of gold as catalyst in organic synthesis and reactivity of bisenamines for three different reactions, leading to potentially useful intermediates.

N‐Alkylamine sind Schlüsselintermediate in der Synthese von Feinchemikalien, Farb‐ und Naturstoffen und deshalb wertvolle Bausteine in der organischen Chemie. Entsprechend ist die Entwicklung nachhaltiger und effizienter Protokolle für die Synthese von N‐Alkylaminen von großem Interesse in der Industrie und Forschung. Bislang wird die Aminsynthese überwiegend über reduktive Protokolle bewerkstelligt, z. B. durch reduktive Aminierung oder durch N‐Alkylierung durch Wasserstoff‐Autotransfer unter Verwendung von Carbonylverbindungen oder Alkoholen als Alkylierungsreagenzien. In den letzten Jahren wurden zudem Carbon‐/Kohlensäurederivate und CO2 als alternative Alkylierungsmittel eingeführt. Die sichere Verwendung, der einfache Zugang und die gute Stabilität dieser Reagenzien treibt die Entwicklung neuer reduktiver Umwandlungen als nützliche Alternativen zu bestehenden Protokollen voran. In diesem Aufsatz fassen wir die literaturbekannten Beispiele von Eintopfmethoden zur reduktiven Alkylierung unter Verwendung von Carbon‐/Kohlensäurederivaten oder CO2 als Alkylierungsreagenzien zusammen. [ABSTRACT FROM AUTHOR]

N‐Alkylamines are key intermediates in the synthesis of fine chemicals, dyes, and natural products, and hence are highly valuable building blocks in organic chemistry. Consequently, the development of greener and more efficient procedures for their production continues to attract the interest of both academic and industrial chemists. Reductive procedures such as reductive amination or N‐alkylation through hydrogen autotransfer by employing carbonyl compounds or alcohols as alkylating agents have prevailed for the synthesis of amines. In the last few years, carboxylic/carbonic acid derivatives and CO2 have been introduced as alternative and convenient alkylating sources. The safety, easy accessibility, and high stability of these reagents makes the development of new reductive transformations with them as N‐alkylating agents a useful alternative to existing procedures. In this Review, we summarize reported examples of one‐pot reductive N‐alkylation methods that use carboxylic/carbonic acid derivatives or CO2 as alkylating agents. [ABSTRACT FROM AUTHOR]