DIBAL-H-mediated N-deacetylation of tertiary amides: synthesis of synthetically valuable secondary amines

A rapid DIBAL-H-mediated N-deacetylation of tertiary amides is described under mild conditions, affording synthetically valuable secondary amines in good to excellent yields.

A unified view on catalytic conversion of biomass and waste plastics

Originating from the desire to improve sustainability, producing fuels and chemicals from the conversion of biomass and waste plastic has become an important research topic in the twenty-first century. Although biomass is natural and plastic synthetic, the chemical nature of the two are not as distinct as they first appear. They share substantial structural similarities in terms of their polymeric nature and the types of bonds linking their monomeric units, resulting in close relationships between the two materials and their conversions. Previously, their transformations were mostly studied and reviewed separately in the literature. Here, we summarize the catalytic conversion of biomass and waste plastics, with a focus on bond activation chemistry and catalyst design. By tracking the historical and more recent developments, it becomes clear that biomass and plastic have not only evolved their unique conversion pathways but have also started to cross paths with each other, with each influencing the landscape of the other. As a result, this Review on the catalytic conversion of biomass and waste plastic in a unified angle offers improved insights into existing technologies, and more importantly, may enable new opportunities for future advances.

Electrophile-Dependent Reactivity of Lithiated N-Benzylpyrene-1-Carboxamide

In this paper, we describe the lithiation of N-benzylpyrene-1-carboxamide with RLi-TMEDA. We found that the reaction outcome strongly depends on the electrophile used in the quenching step. The electrophile can be introduced at either the benzylic position or at the C-2 position in the pyrene nucleus. Furthermore, when H⁺ was used as the quencher, the product of the intramolecular carbolithiation of the pyrene K-region was formed. Dehydrogenation of the obtained compound with DDQ allowed the synthesis of a novel nitrogen polycyclic compound with an aza-benzo[c,d]pyrene (azaolympicene) skeleton. Attempts to extend the reaction scope to the amides substituted in the phenyl ring 8a and 8b gave an unexpected result. The reaction of both compounds with BuLi gave 1-valerylpyrene (9) in good yield. Photophysical properties, including absorption spectra, emission spectra and quantum yields of the emission of selected products, were studied and discussed.

CO2 Reduction to Methanol in the Liquid Phase: A Review

Excessive carbon dioxide (CO₂ ) emissions have been subject to extensive attention globally, since an enhanced greenhouse effect (global warming) owing to a high CO₂ concentration in the atmosphere could lead to severe climate change. The use of solar energy and other renewable energy to produce low-cost hydrogen, which is used to reduce CO₂ to produce bulk chemicals such as methanol, is a sustainable strategy for reducing carbon dioxide emissions and carbon resources. CO₂ conversion into methanol is exothermic, so that low temperature and high pressure are favorable for methanol formation. CO₂ is usually captured and recovered in the liquid phase. Herein, the emerging technologies for the hydrogenation of CO₂ to methanol in the condensed phase are reviewed. The development of homogeneous and heterogeneous catalysts for this important hydrogenation reaction is summarized. Finally, mechanistic insight on CO₂ 's conversion into methanol over different catalysts is discussed by taking the available reaction pathways into account.

Combined KOH/BEt3 Catalyst for Selective Deaminative Hydroboration of Aromatic Carboxamides for Construction of Luminophores

The selective catalytic C-N bond cleavage of amides into value-added amine products is a desirable but challenging transformation. Molecules containing iminodibenzyl motifs are prevalent in pharmaceutical molecules and functional materials. Here we established a combined KOH/BEt₃ catalyst for deaminative hydroboration of acyl-iminodibenzyl derivatives, including nonheterocyclic carboxamides, to the corresponding amines. This novel transition-metal-free methodology was also applied to the construction of Clomipramine and luminophores.

Homogeneous and heterogeneous catalytic reduction of amides and related compounds using molecular hydrogen

Catalytic hydrogenation of amides is of great interest for chemists working in organic synthesis, as the resulting amines are widely featured in natural products, drugs, agrochemicals, dyes, etc. Compared to traditional reduction of amides using (over)stoichiometric reductants, the direct hydrogenation of amides using molecular hydrogen represents a greener approach. Furthermore, amide hydrogenation is a highly versatile transformation, since not only higher amines (obtained by C–O cleavage), but also lower amines and alcohols, or amino alcohols (obtained by C–N cleavage) can be selectively accessed by fine tuning of reaction conditions. This review describes the most recent advances in the area of amide hydrogenation using H₂ exclusively and molecularly defined homogeneous as well as nano-structured heterogeneous catalysts, with a special focus on catalyst development and synthetic applications.

Catalytic hydrogenation of amides is a pivotal chemical transformation for both research labs and chemical production in industry. Here, the authors comprehensively review this topic by including state-of-art homogeneous and heterogeneous catalysts that can hydrogenate amides and related compounds.

CeO2-x quantum dots with massive oxygen vacancies as efficient catalysts for the synthesis of dimethyl carbonate

CeO2-x quantum dots with massive oxygen vacancies are obtained by a one-step single molecular synthesis strategy. The yield of dimethyl carbonate from CO2 and methanol is more than 5 times that for commercial CeO2 nanoparticles.

Homogeneous cobalt-catalyzed deoxygenative hydrogenation of amides to amines

Herein, the first general and efficient homogeneous cobalt-catalyzed deoxygenative hydrogenation of amides to amines is presented.

Molecularly Defined Manganese Catalyst for Low-Temperature Hydrogenation of Carbon Monoxide to Methanol

Methanol synthesis from syngas (CO/H₂ mixtures) is one of the largest manmade chemical processes with annual production reaching 100 million tons. The current industrial method proceeds at high temperatures (200-300 °C) and pressures (50-100 atm) using a copper-zinc-based heterogeneous catalyst. In contrast, here, we report a molecularly defined manganese catalyst that allows for low-temperature/low-pressure (120-150 °C, 50 bar) carbon monoxide hydrogenation to methanol. This new approach was evaluated and optimized by quantum mechanical simulations virtual high-throughput screenings. Crucial for this achievement is the use of amine-based promoters, which capture carbon monoxide to give formamide intermediates, which then undergo manganese-catalyzed hydrogenolysis, regenerating the promoter. Following this conceptually new approach, high selectivity toward methanol and catalyst turnover numbers (up to 3170) was achieved. The proposed general catalytic cycle for methanol synthesis is supported by model studies and detailed spectroscopic investigations.

Palladium doping of In2O3 towards a general and selective catalytic hydrogenation of amides to amines and alcohols

The first general heterogeneous hydrogenation of amides to amines and alcohols is performed under additive-free conditions and without product de-aromatization by applying a Pd-doped In₂O₃ catalyst.

Hydride-catalyzed selectively reductive cleavage of unactivated tertiary amides using hydrosilane

The first hydride-catalyzed reductive cleavage of tertiary amides using the hydrosilane as reducing reagent has been developed. This transition-metal-free process may offer a versatile alternative to current systems for the selective reductive cleavage of amides.