In this study, we present the preparation and application of a new manganoporphyrin Hf-MOF catalyst, Hf-PCN-222(Mn) for the direct oxidative carboxylation of alkenes with CO₂, leading to the effective formation of cyclic organic carbonates (COCs). In contrast to the conventional two-step process, this one-step methodology eliminates the need for the preparation, purification, and handling of epoxides. Hf-PCN-222(Mn) operates under very mild conditions, enabling the synthesis of a wide variety of COCs from alkenes (23 examples, up to 75% yield), as well as the chemoselective and size-selective carboxylation of dienes (7 examples, up to 61% yield). Additionally, we observed that Hf-PCN-222(Mn) could be recycled multiple times without significant loss of activity, providing insight into the sustainability of this approach.

The electrochemical hydrogenation of enones and alkenes using commercial nickel foam and an aqueous acidic solution is presented. The reaction shows excellent selectivity in CC vs. CO reduction, with enhanced activity when using 7% of nBuOH as cosolvent. The method presents good applicability and recyclability properties, with more than 30 different substrates explored, and it can be recycled at least 15 times. Toxicological and screening life cycle assessments were used to identify potential “hotspots” of environmental and human health impact during the development phase of the method, as well as to evaluate the performance of the electrochemical nickel method against the conventional use of Pd/C and H₂ gas.

The unique π-activation ability of gold has long served as the trademark for gold-catalyzed reactions. The reactivity of Au(I) and Au(III) complexes as excellent π-Lewis acids has been well explored by researchers, resulting in a plethora of publications in the past two decades. By leveraging the tunable π-activation properties, researchers continue to explore diverse reactivities such as the functionalization of C–C multiple bonds, enyne cycloisomerization, diyne cycloisomerization, carbene transfer reactions, etc. In recent years, the advances in Au(I)/Au(III) redox catalysis have gained momentum, making gold a potential contender in the realm of transition-metal-catalyzed cross-coupling reactions.

Conversion of carbon dioxide (CO₂) into value-added products is aimed to develop scalable technologies to promote a circular economy. While the electrochemical reduction of CO₂ to carbon monoxide (CO) and formic acid has advanced significantly, a major challenge remains achieving further reduced and more energy-dense products, such as methanol (MeOH), through sustainable pathways. Herein, we report a molecular electrode capable of direct six-electron reduction of CO₂ to MeOH using water as a proton source with a global Faradaic efficiency (FE_G) of 22% and product selectivity of 61% for MeOH. The design consists of an active copper-hydride center surrounded by two closely spaced benzimidazole–hydride units, facilitating the catalytic transfer of three hydrides to produce MeOH. The concurrent formation of formic acid and the absence of formaldehyde suggest that MeOH is generated via a formato pathway. DFT investigations revealed the complete mechanistic pathway, which supports the experimental observations. The morphology and stability of the electrode were evaluated before and after prolonged electrolysis (12 h) experiments using electron microscopic techniques.

A method for the synthesis of benzoic acids from aryl iodides using two of the most abundant and sustainable feedstocks, carbon dioxide (CO₂) and water, is disclosed. Central to this method is an effective and selective electrochemical reduction of CO₂ (eCO₂RR) to CO, which mitigates unwanted dehalogenation reactions occurring when H₂ is produced via the hydrogen evolution reaction (HER). In a 3-compartment set-up, CO₂ was reduced to CO electrochemically by using a surface-modified silver electrode in aqueous electrolyte. The ex-situ generated CO further underwent hydroxycarbonylation of aryl iodides by MOF-supported palladium catalyst in excellent yields at room temperature. The method avoids the direct handling of hazardous CO gas and gives a wide range of benzoic acid derivatives. Both components of the tandem system can be recycled for several consecutive runs while keeping a high catalytic activity.

The catalytic alkylation of amines with alcohols is a highly atom-economical approach that produces water as the sole by-product. Existing catalytic systems lack generality and are primarily applicable to electron-poor amines or to non-oxidizable amines, such as anilines. The outstanding effectiveness of an Ir-NHC catalyst in forming C−N bonds from alcohols and amines, both aliphatic and aromatic, is presented here. The catalyst performs remarkably under mild conditions, even at room temperature, attaining complete selectivity in all tested cases toward monoalkylation, even for challenging aliphatic amines, and under base-free conditions. Thorough mechanistic investigation to understand the outstanding activity and selectivity, combining experimental, theoretical, and both in situ and ex situ X-ray absorption spectroscopy (XAS) studies, are presented.

Hydrogenations are fundamental transformations in organic synthesis, and the industrial applications span from food, petrochemical, fine chemicals to pharmaceuticals synthesis where hydrogenations of multifunctional molecules should be carried out in a chemoselective way. In this concept article we aim at providing an overview on the activation of molecular hydrogen (H2) via heterolytic dissociation, which is responsible to unlock high activity of gold catalysts for chemoselective hydrogenations. The key benefit of heterolytically dissociated H species is their preference for hydrogenating polar unsaturated groups like C=O, C=N, and C=S, as these polar bonds are ideal acceptors for proton and hydride pairs. We will provide examples on how to obtain enhanced chemoselectivity on alkynes, α, β-unsaturated aldehydes and nitro-compounds hydrogenations with gold catalysts.

The acid mediated ortho-iodination of Weinreb amides using a readily available catalyst is described. The selective ortho-iodination of Weinreb amides, challenging substrates in directed C–H activations, and also of benzamides is achieved. The process works under mild conditions and tolerates air and moisture, having a great potential for industrial applications. The methodology can be applied under mechanochemical conditions maintaining the reaction outcome and selectivity. 

A novel iron-catalyzed borylation of propargylic acetates leading to allenylboronates has been developed. The method allows the preparation of a variety of di-, tri- and tetrasubstituted allenylboronates at room temperature with good functional group compatibility. Stereochemical studies show that an anti-S_N2’ displacement of acetate by boron occurs; this also allows transfer of chirality to yield enantiomerically enriched allenylboronates. The synthetic utility of this protocol was further substantiated by transformations of the obtained allenylboronates including oxidation and propargylation. 

Unnatural amino acids are valuable building blocks with numerous applications. Here, we present a quantitative technique for accessing mono-N-functionalized amino acids directly from unprotected substrates using alcohols as alkylating agents and an NHC-Ir(III) catalyst. We detail specific steps for catalyst preparation and application, as well as for catalyst recycling. The protocol excludes a few amino acids (l-cysteine, l-lysine, and l-arginine) and secondary alcohols.