Cascade Synthesis Research Articles

Compromised macrophages contribute to progression of MASH to hepatocellular carcinoma in FGF21KO mice.

Metabolic dysfunction-associated steatohepatitis is well accepted as a potential precursor of hepatocellular carcinoma. Previously, we reported that fibroblast growth factor 21 (FGF21) revealed a novel anti-inflammatory activity via inhibiting the TLR4-IL-17A signaling, which could be a potential anticarcinogenetic mechanism to prevent to MASH-HCC transition. Here, we set out to determine whether FGF21 has a major impact on Kupffer cells' (KCs) ability during MASH-HCC transition. We found aberrant hepatic FGF21 and KC pool in human MASH-HCC. Lack of FGF21 up-regulated ALOX15, which converted the oxidized fatty acids to induce excessive KC death and mobilization of monocyte-derived macrophages (MoMFs) for KC replacement. Lack of FGF21 oversupplied free fatty acids for sphingosine-1-phosphate (S1P) cascade synthesis to mediate MASH-HCC transition via S1P-YAP signaling and cross-talk between tumor cells and macrophages. In conclusion, lack of FGF21 accelerated MASH-HCC transition via the S1P-AP signaling. Compromised MoMFs could present as tumor-associated macrophage phenotype rendering tumor immune microenvironment for MASH-HCC transition.

Cascade Synthesis in Water: Michael Addition/Hemiketalization/Retro-Claisen Fragmentation Catalyzed by CatAnionic Vesicular Nanoreactor from Dithiocarbamate.

N,N-didodecylammonium N,N-didodecyldithiocarbamate (AmDTC-C12C12) underwent self-assembly to form a CatAnionic vesicular nanoreactor in water. AmDTC-C12C12 can be readily prepared by condensation between N,N-didodecylamine and carbon disulfide. Previously, the cascade Michael addition/hemiketalization/retro-Claisen fragmentation was reported, but it required petroleum-based organic solvents as reaction media. Herein, the application of AmDTC-C12C12 in aqueous cascade synthesis is investigated. Initially, we explored the catalytic activity of AmDTC-C12C12 (10 mol%) in the synthesis of 4H-chromene through a double-cascade Michael addition/hemiketalization. The reaction occurred in water at room temperature using 2-hydroxy-trans-b-nitrostyrene as Michael acceptor and acetylacetone as Michael donor yielding 2-chromanol intermediates. Subsequent acidic dehydration of 2-chromanols produced 4H-chromenes with moderate yields (34-60%) and phenyl acetates of g-nitro ketone as co-products (13-27%), deriving from retro-Claisen fragmentation. Surprisingly, using Michael donors with aromatic moieties on the 1,3-dicarbonyls resulted in spontaneous triple-cascade Michael addition/hemiketalization/retro-Claisen fragmentation in water, without the need for acidic dehydration. The g-nitro ketones were obtained as sole products, with no detection of 4H-chromenes, in moderate to high yields (31-84%) for symmetrical 1,3-dicarbonyl containing two aromatic groups. Unsymmetrical 1,3-dicarbonyl bearing aromatic/aliphatic or aromatic/aromatic groups afforded g-nitro ketones in favorable yields (73-97%).

Cascade Synthesis of Fe-N2-Fe Dual-Atom Catalysts for Superior Oxygen Catalysis.

Dual-atom catalysts (DACs) have been proposed to break the limitation of single-atom catalysts (SACs) in the synergistic activation of multiple molecules and intermediates, offering an additional degree of freedom for catalytic regulation. However, it remains a challenge to synthesize DACs with high uniformity, atomic accuracy, and satisfactory loadings. Herein, we report a facile cascade synthetic strategy for DAC via precise electrostatic interaction control and neighboring vacancy construction. We synthesized well-defined, uniformly dispersed dual Fe sites which were connected by two nitrogen bonds (denoted as Fe-N2-Fe). The as-synthesized DAC exhibited superior catalytic performances towards oxygen reduction reaction, including good half-wave potential (0.91 V), high kinetic current density (21.66 mA cm-2), and perfect durability. Theoretical calculation revealed that the DAC structure effectively tunes the oxygen adsorption configuration and decreases the cleavage barrier, thereby improving the catalytic kinetics. The DAC-based zinc-air batteries exhibited impressive power densities of 169.8 and 52.18 mW cm-2 at 25 °C and -40 °C, which is 1.7 and 2.0 times higher than those based on Pt/C+Ir/C, respectively. We also demonstrated the universality of our strategy in synthesizing other M-N2-M DACs (M=Co, Cu, Ru, Pd, Pt, and Au), facilitating the construction of a DAC library for different catalytic applications.

A Lewis Acid-Catalyzed Cascade Synthesis of Fused N-Heterocycles from 2-Alkynylanilines and 2-Formylbenzonitriles: Unveiling Iminoisoindoloindolone and Its Derivatives.

We herein reveal a streamlined synthesis of structurally fused 6-iminoisoindoloindolones via a meticulously orchestrated cascade reaction. This process seamlessly intertwines 2-alkynylaniline and 2-formylbenzonitrile under the catalytic influence of TMSOTf, giving rise to these compounds in remarkable yields that stand as a testament to the efficiency of our approach. Moreover, the versatility of this synthetic strategy extends far beyond mere synthesis, offering a gateway to the creation of both isoindoloindolone and unprecedented diphenylbenzopyrrolizinoisoquinolinone derivatives, thereby opening new horizons in the realm of chemical innovation. Furthermore, the strategic elegance of this synthetic methodology is underscored by its potential for scale-up production and applicability across diverse chemical contexts.

Palladium‐Catalyzed Cascade Cyclization and Alkynylation of 2‐Alkynylphenols with Bromoalkynes

AbstractA palladium‐catalyzed cascade cyclization and alkynylation of 2‐alkynylphenols with bromoalkynes to the synthesis of 3‐alkynylbenzofuran scaffolds has been developed. A variety of 3‐alkynylbenzofuran derivatives were prepared in good yields under mild conditions. Notably, this protocol was applied to the late‐stage modification of bioactive molecule.

New Twists in the Chemistry of Thioureas: 1,3-Thiazolidines as a Vector of Sustainability.

This study introduces a sustainable and pioneering cascade synthesis of 1,3-thiazolidine derivatives under eco-friendly conditions. The methodology transcends traditional approaches yielding complex novel compounds with unique N,S-heterocyclic structures. By operating at room temperature, utilizing green solvents, and minimizing excess of reactants, this procedure offers an innovative pathway for sustainable chemical development. Notably, this method not only prioritizes sustainability but also delivers high-purity products with exceptional yields. The simplicity of the process, requiring only a simple filtration and featuring short reaction times, underscores its efficiency and utility.

A Cascade Synthesis of Indoles.

We report herein an expedient method for the regioselective synthesis of indoles from o-haloanilines and α-ketol-derived N-tosylhydrazones. This two-step, modular synthesis of N-H indoles can be carried out conveniently without purification of intermediates.

Mechanochemical Cascade Synthesis of Zinc Complexes for Catalytic C–S Coupling in One-Pot

Mechanochemical Cascade Synthesis of Zinc Complexes for Catalytic C–S Coupling in One-Pot

Cascade Synthesis of Fe‐N2‐Fe Dual‐Atom Catalysts for Superior Oxygen Catalysis

Dual‐atom catalysts (DACs) have been proposed to break the limitation of single‐atom catalysts (SACs) in the synergistic activation of multiple molecules and intermediates, offering an additional degree of freedom for catalytic regulation. However, it remains a challenge to synthesize DACs with high uniformity, atomic accuracy, and satisfactory loadings. Herein, we report a facile cascade synthetic strategy for DAC via precise electrostatic interaction control and neighboring vacancy construction. We synthesized well‐defined, uniformly dispersed dual Fe sites which were connected by two nitrogen bonds (denoted as Fe‐N2‐Fe). The as‐synthesized DAC exhibited superior catalytic performances towards oxygen reduction reaction, including good half‐wave potential (0.91 V), high kinetic current density (21.66 mA cm‐2), and perfect durability. Theoretical calculation revealed that the DAC structure effectively tunes the oxygen adsorption configuration and decreases the cleavage barrier, thereby improving the catalytic kinetics. The DAC‐based zinc‐air batteries exhibited impressive power densities of 169.8 and 52.18 mW cm‐2 at 25 oC and ‐40 oC, which is 1.7 and 2.0 times higher than those based on Pt/C+Ir/C, respectively. We also demonstrated the universality of our strategy in synthesizing other M‐N2‐M DACs (M= Co, Cu, Ru, Pd, Pt, and Au), facilitating the construction of a DAC library for different catalytic applications.

Single-cell enzymatic cascade synthesis of testolactone enabled by engineering of polycyclic ketone monooxygenase and multi-gene expression fine-tuning

The synthesis of steroids is challenging through multistep steroidal core modifications with high site-selectivity and productivity. In this work, a novel enzymatic cascade system was constructed for synthesis of testolactone by specific C17 lactonization/Δ1-dehydrogenation from inexpensive androstenedione using an engineered polycyclic ketone monooxygenase (PockeMO) and an appropriate 3-ketosteroid-Δ1-dehydrogenase (ReKstD). The focused saturation mutagenesis in the substrate binding pocket was implemented for evolution of PockeMO to eliminate the bottleneck effect. A best mutant MU3 (I225L/L226V/L532Y) was obtained with 20-fold higher specific activity compared to PockeMO. The catalytic efficiency (kcat/Km) of MU3 was 171-fold higher and the substrate scope shifted to polycyclic ketones. Molecular dynamic simulations suggested that the activity was improved by stabilization of the pre-lactonization state and generation of productive orientation of 4-AD mediated by distal L532Y mutation. Based on that, the three genes, MU3, ReKstD and a ketoreductase for NADPH regeneration, were rationally integrated in one cell via expression fine-tuning to form the efficient single cell catalyst E. coli S9. The single whole-cell biocatalytic process was scaled up and could generate 9.0 g/L testolactone with the high space time yield of 1 g/L/h without steroidal by-product, indicating the potential for site-specific and one-pot synthesis of steroid.

Oxalic acid as a dual C1 surrogate for heterogeneous palladium-catalyzed tandem four-component quinazolinone synthesis.

Herein, a heterogeneous Pd/C-catalyzed direct one-step four-component double carbonylative approach for cascade synthesis of 2-aryl quinazolinones has been reported for the first time starting from 2-iodoaniline derivatives and aryl iodides. The given reaction involves the simultaneous implementation of two different gaseous surrogates i.e., ammonium carbamate as an NH3 precursor and oxalic acid as a bi-functional reagent acting as a CO as well as a C-atom surrogate under ligand-free conditions.

Organocatalytic [3+2] Annulation of β-Tetralones with α,β-Unsaturated Aldehydes

AbstractThe NBS-mediated organocatalytic cascade synthesis of 4,5-dihydronaphtho[2,1-b]furan-1-carbaldehydes from α,β-unsaturated aldehydes and 2-tetralones have been developed. In this synthesis strategy, the C1 of in situ generated brominated 2-tetralone was used as identical twin electron donor–acceptor, and the Cβ and Cα of enals were used as the heterogeneous twin electron acceptor–donors. The process has been realized by a synergistic amine/p-TSA catalyzed one-pot cascade Michael addition–cyclopropanation–ring opening–oxa-Michael addition under mild conditions and without the use of transition metals.

Value‐Added Cascade Synthesis Mediated by Paired‐Electrolysis Using an Ultrathin Microenvironment‐Inbuilt Metalized Covalent Organic Framework Heterojunction

AbstractEnergy‐saving and value‐added management in advanced catalysis is highly desirable but is challenged by the limitations of multifunctional catalysts and catalytic modules. Herein, an azo‐linked phthalocyanine‐porphyrin covalent organic framework (COF) with the ultrathin layered nanostructure grown on carbon nanotubes (NiPc‐azo‐H2Pp@CNTs) has been designed and synthesized, which can serve as a highly active and stable bifunctional heterojunction electrocatalyst for selective paired‐electrosynthesis through coupling anodic iodide oxidation reaction and cathodic CO2 conversion. Particularly, the inbuilt local microenvironment conferred by the dihydroporphyrin moieties in COF can act as a proton reservoir to promote the proton relay at the heterojunction interface during the electrocatalytic process. Moreover, through the cascade construction of dual electrocatalytic/organocatalytic modules, the cathode‐generated CO can be further converted to dimethyl carbonate with a yield of 6.21 mmol L−1 h−1, while the anode‐produced iodine can be derived into iodoform on the hundred‐milligram scale. It is worth noting that the value‐added cascade synthesis mediated by paired‐electrolysis using the distinctive and high‐powered electrocatalysts will help advance the sustainable development of industrial intelligent manufacturing.

Oxidant-Assisted Sulfonylation/Cyclization Cascade Synthesis of Alkylsulfonylated Oxindoles via the Insertion of SO2.

An oxidant-assisted tandem sulfonylation/cyclization of electron-deficient alkenes with 4-alkyl-substituted Hantzsch esters and Na2S2O5 for the preparation of 3-alkylsulfonylated oxindoles under mild conditions in the absence of a photocatalyst and transition metal catalyst is established. The mechanism studies show that the alkyl radicals, which come from the cleavage of the C-C bond in 4-substituted Hantzsch esters under oxidant conditions, subsequently undergo the in situ insertion of sulfur dioxide to generate the crucial alkylsulfonyl radical intermediates. This three-component reaction provides an efficient and facile route for the construction of alkylsulfonylated oxindoles and avoids the use of highly toxic alkylsulfonyl chlorides or alkylsulfonyl hydrazines as alkylsulfonyl sources.

Metal-Free Nitrogen-Doped Mesoporous Carbons for the Mild and Selective Synthesis of Pyrroles from Nitroarenes via Cascade Reaction.

The cascade synthesis of pyrroles from nitroarenes is an attractive alternative strategy. However, metal catalysts and relatively high temperatures cover the existing reported catalytic systems for this strategy. The development of nonmetallic heterogeneous catalytic systems for the one-pot synthesis of pyrrole from nitroarenes under mild conditions is both worthwhile and challenging. Herein, we describe an exceptionally efficient method for the synthesis of N-substituted pyrroles by the reductive coupling of nitroarenes and diketones over heterogeneous metal-free catalysts under mild conditions. Nonmetallic NC-X catalysts with high activity were prepared from the pyrolysis of well-defined ligands via simple sacrificing hard template methods. Hydrazine hydrate, formic acid, and molecular hydrogen can all be used as reducing agents in the hydrogenation/Paal-Knorr reaction sequence to efficiently synthesize various N-substituted pyrroles, including drugs and bioactive molecules. The catalytic system was featured with good tolerance to sensitive functional groups and no side reactions such as dehalogenation and aromatics hydrogenation. Hammett correlation studies have shown that the electron-donating substituents are beneficial for the one-pot synthesis of N-substituted pyrroles. The results established that the outstanding performance of the catalyst is mainly attributed to the contribution of graphitic N in the catalyst as well as the promotion effect of the mesoporous structure on the reaction.

Utilizing microbial metabolite in catalytic cascade synthesis of conjugated oligomers for In-Situ regulation of biological activity

Despite the advances of multistep enzymatic cascade reactions, their incorporation with abiotic reactions in living organisms remains challenging in synthetic biology. Herein, we combined microbial metabolic pathways and Pd-catalyzed processes for in-situ generation of bioactive conjugated oligomers. Our biocompatible one-pot coupling reaction utilized the fermentation process of engineered E. coli that converted glucose to styrene, which participated in the Pd-catalyzed Heck reaction for in-situ synthesis of conjugated oligomers. This process serves a great interest in understanding resistance evolution by utilizing the inhibitory activity of the synthesized conjugated oligomers. The approach allows for the in-situ combination of biological metabolism and CC coupling reactions, opening up new possibilities for the biosynthesis of unnatural molecules and enabling the in-situ regulation of the bioactivity of the obtained products.

Improvement of an enzymatic cascade synthesis of nicotinamide mononucleotide via protein engineering and reaction-process reinforcement.

Enzymatic synthesis of β-nicotinamide mononucleotide (NMN) from D-ribose has garnered widespread attention due to its cheap material, the use of mild reaction conditions, and the ability to produce highly pure products with the desired optical properties. However, the overall NMN yield of this method is impeded by the low activity of rate-limiting enzymes. The ribose-phosphate diphosphokinase (PRS) and nicotinamide phosphoribosyltransferase (NAMPT), that control the rate of the reaction, were engineered to improve the reaction efficacy. The actives of mutants PRS-H150Q and NAMPT-Y15S were 334% and 57% higher than that of their corresponding wild-type enzymes, respectively. Furthermore, by adding pyrophosphatase, the byproduct pyrophosphate which can inhibit the activity of NAMPT was degraded, leading to a 6.72% increase in NMN yield. Following with reaction-process reinforcement, a high yield of 8.10gL-1 NMN was obtained after 3h of reaction, which was 56.86-fold higher than that of the stepwise reaction synthesis (0.14gL-1 ), indicating that the in vitro enzymatic synthesis of NMN from D-ribose and niacinamide is an economical and feasible route.

Cascade Synthesis of New Indole-Containing Pentacyclic Scaffolds Mediated by Aryl and Iminyl Radicals.

A five-step approach, starting from simple 1,5-disubstituted indoles, has been implemented for the synthesis of diversely substituted indole-pyrido-indene pentacyclic compounds up to 54 % yield via domino radical-mediated processes in the presence of the radical reagents DLP/TTMSS and AIBN/TTMSS. Reactions proceeded with diverse key starting radical cyano-precursors strategically synthesized which were subsequently transformed into the target pentacyclic compounds through an aryl/iminyl radical-mediated domino reactions sequence. In addition to the routine spectroscopic techniques, the structure of radical precursors, as well as, the target pentacyclic products were unequivocally established by single crystal X-ray diffraction, confirming the effectiveness of the proposed synthetic sequence.

Evaluating Multienzyme Cascade Routes for Pharmaceutically Relevant Molecules

AbstractThe constant demand for sustainable approaches to pharmaceutical synthesis has thrived the enzyme catalysis (biocatalysis) field. The most sought‐after features like high specificity, environmentally benign, and biodegradable nature have rendered enzymatic processes predominantly eco‐friendly. Owing to these merits, biocatalysis is now being developed extensively to exploit their applications in designing alternate and sustainable synthetic routes for manufacturing pharmaceuticals, in line with green chemistry principles. Further, combining multiple enzymes in one‐pot is a highly efficient methodology as it eliminates intermediate isolation, shifts equilibrium in the forward direction, and proceeds in ambient aqueous conditions. This review highlights the importance of recently developed multienzyme cascade synthesis of pharmaceutically important bioactive molecules by relating them with their well‐known chemical route.

A Metal‐Free System for Conversion of Alcohols to Amides Using tert‐Butyl Nitrite

AbstractA transition metal‐free cascade synthesis of amides from alcohols was developed. Various alcohols reacted with N‐hydroxyimides by tert‐butyl nitrite to generate N‐hydroxyimide esters. The resulting active esters were subsequently reacted with amines to generate amides in one pot. Further, we have illustrated the application of the developed protocol in synthesizing anti‐Alzheimer compounds. A detailed mechanistic exploration was also carried out.