The Methylation Effect in Medicinal Chemistry

Synthesis of N-methyl secondary amides via diboronic acid anhydride-catalyzed dehydrative condensation of carboxylic acids with aqueous methylamine

In this study, we present the first catalytic methodology for synthesizing N-methyl secondary amides via dehydrative condensation of hydroxycarboxylic acids with readily available and safe aqueous methylamine, employing diboronic acid anhydride (DBAA) as the catalyst. DBAA catalysis can also be applied to direct amidations using aqueous ethylamine or aqueous dimethylamine. Moreover, we demonstrate the applicability of this catalytic system for the concise synthesis of eight biologically active compounds containing β-amino alcohol motifs, including halostachine, synephrine, longimammine, phenylephrine, metanephrine, normacromerine, etilefrine, and macromerine.

In vitro and in silico evaluation of synthetic compounds derived from bi-triazoles against asexual and sexual forms of Plasmodium falciparum

BACKGROUND

Despite advances in malaria chemotherapy, the disease continues to claim thousands of lives annually. Addressing this issue requires the discovery of new compounds to counteract resistance threatening the current therapeutic arsenal. In this context, bi-triazoles are substances with diverse biological activities, showing promise as lead compound to fight malaria. Triazoles are heterocyclic structures composed of five members, including three nitrogen atoms and two double bonds. Bi-triazoles, the focus of this study, are derivatives of triazoles consisting of two triazole rings (nitrogen heterocyclic) with isolated nuclei lacking a spacer and two substituents at each end. The goal of the present study was to assess the in vitro and in silico, antimalarial activity of bi-triazole compounds 14c, 14d, 13c, and 13d against asexual and sexual forms of Plasmodium falciparum.

METHODS

For in silico predictions, the software OSIRIS, Molinspiration, and ADMETlab were employed. To determine the 50% inhibitory concentration (IC50) on the asexual forms, the W2 clone was used, while the strain NF54 was used to assess inhibition of sexual forms. Cytotoxicity was evaluated using the HepG2 cell line, and haemolysis tests were conducted. Additionally, the selectivity index (SI) of each compound was calculated.

RESULTS

In silico analyses of physicochemical properties revealed that all compounds have favorable potential for drug development. Pharmacokinetics predictions also provided important, novel insights into this chemical class. Antimalarial activity tests showed that compounds 14d and 13d exhibited promising activity, with IC50 values of 3.1 and 4.4 µM, respectively. Antimalarial activity of compounds 14d and 13d may be related to the presence of methyl acetate in substituent R2 conjugated to the bi-triazole. None of the compounds demonstrated cytotoxic or haemolytic activity, with SI values above 51 for the three most active compounds, highlighting their selectivity. For the sexual forms, compounds 14c and 14d were classified as having a high potential to block malaria transmission.

CONCLUSION

Overall, the in vitro and in silico results showed that bi-triazole compounds may guide new biological investigation for malaria, enabling the identification and development of more active and selective antimalarial agents.

Harnessing the Magic Methyl Effect: Discovery of CLPP-2068 as a Novel HsClpP Activator for the Treatment of Diffuse Large B-Cell Lymphoma

The "magic methyl effect" has facilitated the successful development of numerous pharmaceutical compounds. During the development of HsClpP activators, we found that incorporating methyl groups into the bicyclic imipridone scaffolds significantly enhanced the activator activity at the enzymatic level. Further structure-activity relationship studies led to the identification of a highly promising compound, CLPP-2068, which exhibited an EC50 value of 50.4 nM. Cryo-electron microscopy techniques and computational analyses demonstrated that the introduction of methyl groups facilitated the formation of additional CH-π interactions between CLPP-2068 and HsClpP, thereby lowering the energy barriers during the binding process. Furthermore, additional pharmaceutical analyses indicated that CLPP-2068 exhibited favorable pharmacokinetic properties and effectively mitigated the potential hERG toxicity observed in imipridone-based HsClpP activators. Collectively, CLPP-2068, developed using the magic methylation strategy, holds potential as a therapeutic agent for the treatment of diffuse large B-cell lymphoma, thereby expanding the clinical indications for HsClpP activators.

Conformational Role of Methyl in the Potency of Cyclohexane-Substituted Squaramide CCR6 Antagonists

CCR6 is a chemokine receptor that mediates the migration of pathogenic inflammatory leukocytes to sites of inflammation in response to its ligand, CCL20. Herein we report the design of a potent CCR6 antagonist capable of inhibiting the chemotactic migration of CCR6+ T cells in vitro. Key to this finding was the discovery of a remarkable methyl substituent effect on antagonist potency. A 365-fold improvement in potency was observed for the cis-2-methylcyclohexanamine analogue compared to the unsubstituted cyclohexanamine derivative. Evidence generated through the characterization of conformationally restricted analogues supports the conclusion that the large potency enhancement is the result of the methyl substituent biasing the cyclohexane ring ground state conformation to favor that of the bound ligand and thus decreasing the ligand strain energy.

Short Scalable Route to Bis-morpholine Spiroacetals and Oxazepane Analogues: Useful 3D-Scaffolds for Compound Library Assembly

sp3-Rich molecular scaffolds incorporating nitrogen heterocycles represent important starting points for assembling compound screening libraries and drug discovery. Herein, we report a four-step synthesis of a conformationally well-defined sp3-rich scaffold incorporating two morpholine rings embedded within a spiroacetal framework. The synthesis involves the intermediacy of a 2-chloromethyl-substituted morpholine, accessed from epichlorohydrin and readily available β-aminoalcohols. Base-mediated dehydrochlorination affords an exocyclic enol ether, from which the second morpholine ring is constructed in two steps. Scaffold synthesis is high-yielding and can be performed on a large scale. The methodology allows ready substitution of one-or both- of the morpholine rings for 1,4-oxazepanes and the generation of 6,7- and 7,7-spiroacetal analogues, which are virtually unexplored in drug discovery. Substituted 6,6-systems can be prepared and, in some instances, undergo acid-mediated anomerization to deliver the scaffolds in high diastereoselectivity. The two amine functionalities embedded in the 6,6- and 6,7-spiroacetal scaffolds were sequentially functionalized to provide a diverse physical compound library. These library compounds occupy a similar chemical space to small-molecule drugs that have been approved for clinical application by the Food and Drug Administration yet are structurally dissimilar and may therefore act upon novel targets, representing attractive starting materials for drug discovery.

Design, synthesis, biological evaluation, and mechanism of action of new pyrazines as anticancer agents in vitro and in vivo

Cancer is the second leading cause of mortality worldwide. The development of innovative antitumor pharmaceuticals is urgently needed to alter this circumstance. N-heterocycles, pyrazines for example are prevalent pharmacophores in the architecture of anticancer medicines. This research involved the design and synthesis of seventy-seven new pyrazine derivatives, followed by an evaluation of their anticancer activity in vitro and in vivo. Several new pyrazines exhibiting remarkable antiproliferative activity and selectivity were identified. The links between structure and function were analyzed, and the mechanisms of action were examined. Our mechanistic investigations indicated that these chemicals triggered mitochondria-associated apoptosis in cancer cells. Moreover, they suppressed the phosphorylation of STAT3, concomitant with the down-regulation of BcL-2, BcL-XL, c-Myc, XIAP, GLI1, TAZ, MCL1, JAK1, JAK2 and up-regulation of Bax, p21. Furthermore, the lead compounds B-11 and C-27 demonstrated significant anticancer activity in vivo in the SKOV3 xenograft nude mouse model. Our research establishes a basis for the identification of pyrazines as JAK/STAT3 inhibition based anticancer lead compounds.

Biosynthesis of the Antifungal Polyhydroxy-Polyketide Acrophialocinol

Bioactivity-guided isolation identified the main antifungal compounds produced by Acrophialophora levis as the new polyhydroxy-polyketides acrophialocinol (1) and acrophialocin (2). Their biosynthesis was elucidated by heterologous reconstitution in Aspergillus oryzae and involves an α-ketoglutarate-dependent dioxygenase-catalyzed α-hydroxylation, resulting in the formation of a tertiary alcohol that is indispensable for antifungal activity. Furthermore, self-resistance toward the polyhydroxy-polyketides is mediated by a conserved RTA1-like protein encoded in the acr biosynthetic gene cluster.

Meta-Dimethylation of Arenes via Catellani Reaction from Aryl Thianthrenium Salts

Here we report the reaction of aryl thianthrenium salts that allows selective functionalization of the meta position of arenes. The combination of a site-selective thianthrenation with a Catellani reaction provides access to 3,5-dimethylated arenes. The developed reaction is complementary to the previously discovered reductive ipso-alkylation of aryl thianthrenium salts and extends the possibilities for late-stage methylation of arenes with a single aryl thianthrenium salt.

Catalytic Asymmetric Synthesis and Applications of Stereogenic β'-Methyl Enones and β,β'-Dimethyl Ketones

The "Magic Methyl" effect has received tremendous interest in medicinal chemistry due to the significant pharmacological and physical modification of properties that have been observed upon introducing a methyl group, especially, a stereogenic methyl group into potential chiral drug candidates. The prevalence of stereogenic β-methyl ketone structural motifs in bioactive compounds and natural products has long motivated the development of enantioselective strategies toward their synthesis. Herein, we have rationally designed a Rh-catalyzed asymmetric monohydrogenation of readily-available β'-methylene conjugated enones with high efficiency and remarkable site-selectivity and enantioselectivity control for the practical construction of enantioenriched β'-methyl unsaturated enones that are difficult to access by other methods. Control experiments revealed that the conjugated C=C bond in β'-methylene conjugated enones plays a significant role in enhancing the reactivity of monohydrogenation. This methodology is applicable for the preparation of chiral β,β'-dimethyl ketones through consecutive double asymmetric hydrogenation of β,β'-dimethylene ketones. Detailed mechanistic investigation and DFT studies further provided strong support for a unique processive catalysis pathway for double asymmetric hydrogenation. The synthetic utilities have been demonstrated in the concise synthesis of several key intermediates for bioactive molecules, asymmetric total synthesis of natural products (S)-(+)-ar-Turmerone and (S)-(+)-dihydro-ar-Turmerone, and two C2-symmetric chiral spirocyclic diol frameworks.

A Borenium-Borane Composite for Exhaustive Reduction of Oxo-Chemicals

Borenium ions have attracted significant attention in organic transformations due to their strong Lewis acidity. The reported borenium ions are often stabilized by sterically demanding substituents and strong coordination bonds. Herein, we have synthesized a small steric borenium-equivalent NH3BH2OTf and subjected it to the exhaustive reduction of a carboxylic functional group to a methyl group, which shows broad functional group tolerance. This system can also undergo a reductive deoxygenation reaction of alcohols, ethers, and other oxo-chemicals (>100 examples). The mechanistic studies revealed that the in situ-generated NH3BH2OTf/[NH3BH2(sol)]OTf, rendering the borenium-like properties, plays a crucial role in these transformations by interacting with the O atom of substrates to activate the carbonyl group and facilitating the cleavage of the C-O bond. This work has not only offered a system for the exhaustive reduction of oxo-chemicals but is also of great significance for providing insight into the application of the borenium ions in various reactions.

Assembly Regulates Gamma Radiation Polymerization of Polytelluoxane

Regulating chemical drug's responsiveness to gamma radiation is crucial for achieving better therapeutic effects in cancer treatment. Most research focused on thermodynamic chemical structure design, while little attention was paid to kinetic regulate strategy, which possesses greater universality and security. In this study, we achieved a kinetic-based regulate strategy of gamma radiation reaction, through the construction of microphase environment during polymerization of polytelluoxane (PTeO). We designed hydrophobic segments forming large compound micelles (LCMs) assembly to create kinetically favorable higher concentration for radiation-induced reaction. It exhibited a > ten times higher responsiveness and, as far as we know, merely required a minimum dosage of 5 Gy for polymerization to occur. What's more, by taking advantages of the assembly change with Te-O hydrophilic segments and gamma radiation, polymerization became milder with lower polydispersity than previous methods. Such kinetic-based regulate strategy could offer a novel perspective on the design of radiation-responsive chemoradiotherapy and other radiation-induced chemical process.

Optimization of SHP2 allosteric inhibitors with novel tail heterocycles and their potential as antitumor therapeutics

SHP2, a non-receptor protein tyrosine phosphatase involved in cancers, plays a pivotal role in numerous cellular signaling cascades, including the MAPK and PD-L1/PD-1 pathways. Although several SHP2 allosteric inhibitors have already entered clinical trials, none have been approved to date. Therefore, the development of new SHP2 allosteric inhibitors with improved efficacy is urgently required. Herein, we report the optimization of tail heterocycles in SHP2 allosteric inhibitors using a structure-based drug design strategy. Four series of compounds with different tail skeletons were synthesized, among which D13 showed notable inhibitory activity (IC50 = 1.2 μM) against SHP2. Molecular docking and binding studies indicated that the newly synthesized compounds exerted enzymatic inhibitory effects by directly binding to SHP2 with relatively slow dissociation rates. At the cellular level, Huh7 cells demonstrated heightened sensitivity to the novel SHP2 inhibitors, and D13 exhibited superior antiproliferative activity (IC50 = 38 μM) by arresting G0/G1 cell cycle, facilitating cell apoptosis and suppressing the MAPK signaling pathway. In the in vivo study, D13 displayed significant antitumor activity in a Huh7 xenograft model and possessed favorable druggability with acceptable oral bioavailability (F = 54 %) and half-life (t1/2 = 10.57 h). Collectively, this study lays a robust foundation for further optimization of the tail heterocycle skeleton in SHP2 allosteric inhibitors.

Discovery of novel thiosemicarbazone-acridine targeting butyrylcholinesterase with antioxidant, metal complexing and neuroprotector abilities as potential treatment of Alzheimer's disease: In vitro, in vivo, and in silico studies

Inhibition of cholinesterases, combined with antioxidant activity, metal-chelating capacity, and neuroprotection, is recognized as an effective multitarget therapy for the treatment of Alzheimer's disease (AD). Based on our in-house thiosemicarbazone-acridine compounds, this study recognized these derivatives as possible multi-target-directed ligand (MTDL). Initial screening against cholinesterases identified CL-01, which exhibited a promising IC50 value of 0.71 μM against butyrylcholinesterase (BChE). Twelve new derivatives were designed based on CL-01 aiming to retain the BChE inhibitory activity while incorporating a MTDL profile, including antioxidant properties and metal-complexing abilities. Among the new derivatives, CL-13 maintained a good BChE inhibition (IC50 = 1.15 μM) with improved selective index against acetylcholinesterase (SI = 9.2). The acridine nucleus was important for the activity, as its saturated tetrahydroacridine analogue (TA-01) showed a decrease in cholinesterases inhibition potencies and altered the mode of inhibition, revealing for the first time distinct functional roles for the two nuclei. Moreover, CL-13 emerged as a promising lead compound, demonstrating interesting antioxidant activity (DPPH EC50 = 47.01 μM), chelating capacity of biometals involved in Aβ aggregation and/or oxidative stress, and a lack of neurotoxicity at 50 μM in SH-SY5Y cells. It also exhibited neuroprotective effects in an in vitro oxidative stress model induced by H2O2. Finally, in vivo experiments confirmed that CL-13 effectively reversed scopolamine-induced cognitive impairment, without affecting locomotor activity in the mice.

Magic methylation with methyl-containing peroxides

Methyl groups rank among the most abundant carbon fragments found in natural products and small-molecule pharmaceuticals. The late-stage and environmentally friendly installation of these groups onto biologically active molecules has attracted widespread attention in both industry and academia. In 2008, we published the first use of a methyl radical derived from a peroxide toward a directed transition-metal catalysed C-H methylation. In the past sixteen years, methyl-containing peroxides have proven themselves as robust reagents for introducing methyl groups onto organic molecules. In this review, our goal is to provide a thorough summary of the research advancements achieved in this field thus far.

A General Pd-Catalyzed C2-H Arylation of Benzoxazoles with Highly Sterically Congested Aryl Chlorides Enabled by a Fittingly Tuned Ligand

The benzoxazole core, featuring a sterically congested 2,6-disubstituted aryl fragment at the C2 position, exhibits exclusive three-dimensional structures that are essential for particular applications in material science and pharmaceutical development. Despite their importance, the synthesis of these compounds has posed challenges with an efficient preparation strategy still lacking. In this study, we introduced a new indolylphosphine ligand, PCy2-Man-phos, specifically designed to facilitate the C2-H arylation of benzoxazoles with sterically hindered aryl chlorides in general. The excellent functional group compatibility and rich arene substituted pattern enable the creation of highly decorated and sterically demanding 2-arylbenzoxazole frameworks, showing significant potential for diverse synthetic applications.

Cyclic Sulfoximines as Methyl and Perdeuteromethyl Transfer Agents and Their Applications in Photoredox Catalysis

Benzo[1,3,2]dithiazole-1,1,3-trioxides are bench-stable and easy-to-use reagents. In photoredox catalysis, they generate methyl and perdeuteromethyl radicals which can add to a variety of radical acceptors, including olefins, acrylamides, quinoxalinones, isocyanides, enol silanes, and N-Ts acrylamide. As byproduct, a salt is formed which can be regenerated to the original methylating agent. Flow chemistry provides an option for reaction scale-up further underscoring the synthetic usefulness of these methylation reagents. Mechanistic investigations suggest a single-electron transfer (SET) pathway induced by photoredox catalysis.

Ultrahigh-purity ammonia recovery from synthetic coke wastewater via membrane contactor: Overcoming phenolic interference and assessing cost efficiency

Ammonia recovery from industrial wastewater using membrane contactor processes is emerging as a promising method owing to the diverse applications of ammonia. This study uniquely addressed ammonia recovery from coke plant wastewater, which is challenging due to the presence of numerous toxic and volatile phenolic compounds. Experiments were conducted using a synthetic coke plant effluent to assess the effects of various pH levels and temperatures on ammonia recovery. Specifically, the aim was to achieve high-purity ammonia recovery while minimizing the permeation of phenolic compounds. The results demonstrate that ammonia recovery in the membrane contactor processes is highly efficient, even in the presence of phenolic compounds. During temperature variations at 25 °C and 40 °C, the recovery of ammonia increased from 42.36% to 52.97% at pH 11. Additionally, increasing the pH of a feed solution from 7 to 12 significantly increased the ammonia content to 58.3%. At this pH, the recovered ammonia was of exceptional purity (>99%), with phenol, p-Cresol, and 2,4-xylenol present at negligible concentrations (0.001%, 0.002%, and 0.004%, respectively). This was attributed to the ionization of phenolic compounds at higher pH levels, which prevents their permeation through the hydrophobic membrane. The estimated cost analysis revealed that the membrane contactor process at pH 12 was approximately 1.41 times more cost-effective than conventional air-stripping processes over eight years of operating period (pH-12 membrane contactor: $19.79; pH-12 air stripping: $23.75). This study provides a detailed analysis of the optimal conditions for selective ammonia recovery from complex wastewater, highlighting both effective treatment and sustainable resource recovery and offering a superior alternative to traditional methods.

Discovery of CLPP-1071 as an Exceptionally Potent and Orally Efficacious Human ClpP Activator with Strong In Vivo Antitumor Activity

Human sapiens caseinolytic protease P (ClpP) is essential for maintaining mitochondrial proteome homeostasis, and its activation is increasingly recognized as a promising cancer therapy strategy. Herein, based on structure-guided drug design, we discovered a series of potent ClpP activators by introducing a methyl group to the imipridone scaffold of the ClpP activator ONC201 in Phase III clinical trials. Through structural optimization of the lead compound, the most optimal compound, CLPP-1071, exhibited exceptionally potent ClpP agonistic activity (EC50 = 23.5 nM, 107.1-fold stronger than ONC201) and inhibited the proliferation of HL60 cells (IC50 = 4.6 nM, 169.2-fold stronger than ONC201). CLPP-1071 possesses good pharmacokinetic properties and effectively prolongs the lifespan in the MOLM13 and HL60 xenograft models in mice through oral administration. CLPP-1071 is the most potent and orally efficacious ClpP activator reported to date.

Catalytic Reductive Amination and Tandem Amination-Alkylation of Esters Enabled by a Cationic Iridium Complex

Reported herein is a convenient and efficient method for one-pot, catalytic reductive amination, as well as the first multi-component tandem reductive amination-functionalization of bench-stable and readily available common carboxylic esters. This method is based on the cationic [Ir(COD)2]BArF-catalyzed chemoselective hydrosilylation of esters, followed by one-pot acid-mediated amination and nucleophilic addition. The reaction was conducted under mild conditions at a very low catalyst loading (0.1 mol % of Ir), which could be further reduced to 0.001 mol %, as demonstrated by a reaction at a 15 g scale. The method is highly versatile, allowing the use of esters with or without α-protons for the N-mono-alkylation of primary and secondary amines to produce diverse secondary and tertiary amines, as well as α-branched/functionalized amines. The method is highly chemoselective and tolerates a variety of functional groups such as bromo, trifluoromethyl, ester, and cyano groups. The value of the method was demonstrated by the one-step catalytic synthesis of two bio-relevant N-mono-methyl α-amino esters and the antiparkinsonian agent piribedil, as well as by the use of two shorter chain triglycerides as alkylating feedstock.

Pnictogen and Chalcogen Salts as Alkylating Agents

Alkylation reactions and their products are considered crucial in various contexts. Synthetically, the alkylation of a nucleophile is usually promoted using hazardous alkyl halides. Here, we aim to highlight the potential of pnictogen (ammonium or phosphonium) and chalcogen salts (sulfonium, selenonium, and telluronium) to function as alkylating agents. These compounds can be considered as non-volatile electrophilic alkyl reservoirs. We will center our discussion on the strategies developed in recent years to expand the synthetic utility of these salts in terms of transferable alkyl groups, substrate scope, and product selectivity.

Methyl scanning approach for enhancing the biological activity of the linear peptidic natural product, efrapeptin C

Efrapeptin C (1a) is a large peptidic natural product comprising a 15-mer linear sequence and exerts potent anticancer activity by inhibiting mitochondrial FoF1-ATP synthase. Residues 1-6 and 9-15 of 1a fold into two 310-helical domains and interact with ATP synthase, while the central β-Ala-7-Gly-8 region functions as a flexible linker of the two domains. To enhance the function of 1a by minimally modifying its structure, we envisioned attaching one small methyl group to the β-Ala-7-Gly-8 and designed six methylated analogues 1b-1g, differing only in the position and configuration of the methyl group. We enabled the first solid-phase total synthesis of 1a and unified syntheses of 1b-1g. The growth inhibitory activities of 1a-1g against MCF-7 cells varied significantly: 1f with (S)-β3-hAla-7 and its epimer 1g with (R)-β3-hAla-7 were 4-fold more and 5-fold less potent, respectively, than 1a. Remarkably, the most potent 1f had the most stabilized 310-helical conformation and the highest hydrophobicity, which likely contributed to its effective transfer to the target protein within mitochondria. Moreover, 1f exhibited higher proteolytic stability than 1a. Therefore, the present methyl scanning approach provides a new strategy for changing the original properties of linear peptidic natural products to develop new pharmaceuticals.

Safety evaluation and modulatory effects on innate immune system of pyrazoline-derived compounds

Pyrazolines are compounds that have been studied for their strong biological potential and structure diversity. Several studies demonstrated their biological effectiveness, highlighting their anti-inflammatory potential. This study aimed to evaluate the physicochemical profile, the safety, and the anti-inflammatory effects of four pyrazolines (PH0, PH3, PH4, and PH7). Initially, in silico analysis were performed on SwissADME and QSAR Toolbox platforms. The anti-inflammatory activity was assessed by in vitro and in vivo methodologies. Neutrophils collected from mice peritoneum and macrophages immortalized cell line (Raw 264.7) were stimulated with lipopolysaccharide (LPS), and subsequent measurement of nitric oxide (NO) and IL-1β, TNF, and IL-6 cytokines were performed by ELISA method. The effect on cell migration was evaluated by chemotaxis assay. The effect on efferocytosis was investigated using senescent neutrophils and macrophages from mice's bone marrow. The in silico results suggest suitable properties for a pharmacological prototype for oral administration, with no significant toxic effects. All compounds significantly reduced NO levels, as well as levels of IL-1β, TNF, and IL-6 cytokines. Also, they were able to reduce cell migration and increase efferocytosis. The in vivo air pouch model confirmed the effects of pyrazolines on cell kinetics and on the levels of cytokines (IL-1β and TNF) on the air pouch lavage. All of the pyrazolines evaluated showed to have positive effects on mechanisms that modulate the inflammatory response. Furthermore, the in silico analysis suggests that chemical changes in the structure can lead to improvement of the biological and pharmacokinetics proprieties.

Metallaphotocatalytic triple couplings for modular synthesis of elaborate N-trifluoroalkyl anilines

The integration of trifluoromethyl groups and three-dimensional quaternary carbon moieties into organic molecules has emerged as a prominent strategy in medicinal chemistry to augment drug efficacy. Although trifluoromethyl (hetero)aromatic amines and derivatives are prevalent frameworks in pharmaceuticals, the development of trifluoromethyl-embedded, intricately structured alkyl amine scaffolds for medicinal research remains a significant challenge. Herein, we present a metallaphotoredox multicomponent amination strategy employing 3,3,3-trifluoropropene, nitroarenes, tertiary alkylamines, and carboxylic acids. This synthetic pathway offers notable advantages, including the accessibility and cost-effectiveness of starting materials, high levels of chemo- and regioselectivity, and modularity. Furthermore, this approach enables the synthesis of a broad spectrum of aniline compounds featuring both trifluoromethyl group and distal quaternary carbon motifs along the aliphatic chains. The accelerated access to such elaborate N-trifluoroalkyl anilines likely involves three sequential radical-mediated coupling events, providing insightful implications for the retrosynthesis of potential compounds in organic synthesis and drug discovery.

Pd/C-Catalyzed Selective N-Monomethylation by Transfer Hydrogenation of Urea Derivatives using Methanol as H2 and C1 Sources

N-monomethyl amines are useful intermediates in drugs, natural products, paints. Yet their synthesis is a tremendous challenge due to their high reactivity, typically leading to overmethylation. In this contribution, a highly selective catalytic N-methylation methodology is reported, converting urea derivatives to monomethylated amines, using a commercially available heterogeneous Pd/C catalyst and methanol as unique reagent. Methanol provides a sustainable alternative protocol for the selective preparation of mono-methylated derivatives as it acts as both H2 and C1 sources. In addition, several control experiments were performed to provide a proposal for the mechanism, namely dehydrogenation of methanol and subsequent hydrogenation of urea derivatives, followed by reduction of the in situ formed methyl imine. Importantly, the approach is simple, highly productive and enables novel synthetic procedures for the preparation of monomethylamines from urea derivatives.

Palladium-Catalyzed Cascade Distal C-H Methylation and Cyclization for the Construction of Spirooxindole Skeletons

Transition metal-catalyzed C-H methylation represents a straightforward approach for introducing methyl groups into organic molecules. Herein, we report a palladium-catalyzed alkene-relayed remote C-H methylation reaction that utilizes dimethyl carbonate as the methylation reagent. The aryl groups distal to a bromo group were dimethylated via C-H activation, leading to the formation of spirooxindoles as the final products through C(sp3)-H activation and C(sp3)-C(sp3) coupling. This cascade process involves the formation of four C-C bonds and the activation of three C-H bonds. The reaction not only provides a new approach to C-H methylation but also offers a novel method for constructing spirooxindole skeletons by merging skeleton construction and methylation into a single step.

Substrate-Induced Cooperative Ionic Catalysis: Difunctionalization of Indole Derivatives Employing Dimethyl Carbonate

The global urge to adopt sustainable chemistry has resulted in the development of more environmentally benign strategies (EBS) that use CO2 and CO2-derived chemicals in a step-economic manner. In this context, we investigated a dual C-H methylation and (C═O)-methoxylation of indole derivatives using dimethyl carbonate (DMC) in the presence of catalytic amounts of Cs2CO3. Mechanistic insights include DMF-assisted, DMC-induced cooperative ionic catalysis, which allows DMC to act as both a nucleophilic and an electrophilic precursor, resulting in (C═O)-methoxylation and C-H methylation of N-benzylindolyl ketones.

Sustainable C-H Methylation Employing Dimethyl Carbonate

The use of CO2 and CO2-derived chemicals offers society sustainable and biocompatible chemistry for a variety of applications, ranging from materials to medicines. In this context, dimethyl carbonate (DMC) stands out owing to its low toxicity, high biodegradability, tunable reactivity, and sustainable production. Further, the ability of DMC to act as an ambient electrophile at varied temperatures and reaction conditions in order to produce methoxycarbonylated (via BAC2) and methylated products (via BAL2) is very promising. While the methylation of hetero-H (N-, O-, and S-methylation) with DMC is established and well-reviewed, the C-H methylation reaction with DMC is limited, and there is no specific literature detailing the C-methylation reaction using DMC, creating new opportunities as well as challenges in the same domain. In this context, the present perspective focuses on the new breakthroughs, recent advances, and trends in C-H methylation reactions employing DMC. A critical analysis of the mechanistic course of reactions under each category was undertaken. We believe this timely perspective will offer an in-depth analysis of existing literature with critical remarks, which will certainly inspire fellow researchers across disciplines to understand and pursue cutting-edge research in the area of C-H methylation (alkylation) using DMC and related organic carbonates.

Ru(II)-Catalyzed Sustainable C-H Methylation of Indolines with Organoboranes in Ethanol

A sustainable protocol for Ru(II)-catalyzed regioselective C(sp2)-H methylation of indolines in the presence of ethanol has been explored. A wide array of substituted indolines were successfully methylated via the developed protocol with good to excellent yields. Deuterium labeling experiments suggested the reversible nature of the C-H activation step. Kinetic isotope effect studies revealed that C-H activation might be the rate-determining step. Gram scale reaction and post-transformation reactions of the methylated product demonstrated the potential of the developed protocol.

A Modified Arbuzov-Michalis Reaction for Selective Alkylation of Nucleophiles

The alkylation of nucleophiles is among the most fundamental and well-developed transformations in chemistry. However, to achieve selective alkylation of complex substrates remains a nontrivial task. We report herein a general and selective alkylation method without using strong acids, bases, or metals. In this method, the readily available phosphinites/phosphites, in combination with ethyl acrylate, function as effective alkylating agents. Various nucleophilic groups, including alcohols, phenols, carboxylic acids, imides, and thiols can be alkylated. This method can be applied in the late-stage alkylation of natural products and pharmaceutical agents, achieving chemo- and site-selective modification of complex substrates. Experimental studies indicate the relative reactivity of a nucleophile depends on its acidity and its steric environment. Mechanistic studies suggest the reaction pathway resembles that of the Arbuzov-Michalis reaction.

Silver-Catalyzed 1,2-Thiosulfonylation of Alkenes: Development of a Nucleophilic d3-Methylthiolating Reagent

Development of robust d3-methylthiolating reagents represents an attractive synthetic method to access deuterated molecules in the field of drug discovery. Here, we report a straightforward strategy to prepare electrophilic S-methyl-d3 arylsulfonothioates in one-step without column purification. These reagents exhibit good radical reactivity toward silver-catalyzed vicinal thiosulfonylation of alkenes or 1,6-enynes on water. As a result, simultaneous incorporation of both SCD3 and ArSO2 units into unsaturated carbon-carbon bonds with 100% atom economy has been established. Moreover, the ATRA adducts with >99% D incorporation can serve as nucleophilic d3-methylthiolating synthons via retro-Michael addition under mild basic conditions, providing a good alternative in trideuteromethylthiolating alkyl iodides to access corresponding trideuteromethyl sulfides with high efficiency.

Silane-mediated, facile C-H and N-H methylation using formaldehyde

The use of (para)-formaldehyde for the methylation/alkylation of C(sp2)-H and N-H bonds, utilizing a combination of silane and hexafluoroisopropanol (HFIP) as activators, is reported. Overcoming the complexity of C(sp2)-H methylation on aryl and indole substrates, the process utilizes a Friedel-Crafts alkylation, followed by silane as a hydride donor, under a mild acidic medium. The method has been employed for the synthesis of the antifungal drug butenafine and a derivative of the non-steroidal anti-inflammatory drug (NSAID) flurbiprofen.

Helicase-primase inhibitors for the treatment of herpes simplex virus infections - patent evaluation of WO2023/225162 from Gilead Sciences Inc

Helicase-primase is an interesting target for small-molecule therapy of herpes simplex virus (HSV) infections. With amenamevir already approved for varicella-zoster virus and herpes simplex in Japan and with pritelivir's granted breakthrough therapy designation for the treatment of acyclovir-resistant HSV infections in immunocompromised patients, the target has sparked interest in helicase-primase inhibitors (HPIs). Here, we analyze the first patent application from Gilead in this field, which pursued a me-too approach combining elements from an old Bayer together with a recent Medshine HPI application (which covers the Phaeno Therapeutics drug candidate HN0037). The asset was contributed to Assembly Biosciences, where it is under development as ABI-1179 at the investigational new drug (IND) enabling stage for high-recurrence genital herpes. A structure proposal for indolinoyl derivative ABI-1179 is presented, showing its potential opportunities and limitations compared to other HPIs.

Catalytic undirected methylation of unactivated C(sp3)-H bonds suitable for complex molecules

In pharmaceutical discovery, the "magic methyl" effect describes a substantial improvement in the pharmacological properties of a drug candidate with the incorporation of methyl groups. Therefore, to expedite the synthesis of methylated drug analogs, late-stage, undirected methylations of C(sp3)-H bonds in complex molecules would be valuable. However, current methods for site-selective methylations are limited to activated C(sp3)-H bonds. Here we describe a site-selective, undirected methylation of unactivated C(sp3)-H bonds, enabled by photochemically activated peroxides and a nickel(II) complex whose turnover is enhanced by an ancillary ligand. The methodology displays compatibility with a wide range of functional groups and a high selectivity for tertiary C-H bonds, making it suitable for the late-stage methylation of complex organic compounds that contain multiple alkyl C-H bonds, such as terpene natural products, peptides, and active pharmaceutical ingredients. Overall, this method provides a synthetic tool to explore the "magic methyl" effect in drug discovery.

Cobalt-catalyzed hydrothiolation of alkynes for the diverse synthesis of branched alkenyl sulfides

Alkenyl sulfides have gained increasing prominence in medicinal chemistry and materials. Hydrothiolation of alkynes for the diverse synthesis of alkenyl sulfides is an appealing method. Herein, we report a cobalt-catalyzed Markovnikov hydromethylthiolation of alkynes to afford branched alkenyl methylsulfanes with good yields and high regioselectivity. This method also enables the diverse synthesis of branched alkenyl sulfides. The reaction shows good functional group tolerance and could be scaled up. The mechanistic studies including control experiments, deuterium-labeling experiments, and Hammett plot indicated alkynes insertion followed by electrophilic thiolation pathway.

Radical Cascade Cyclization of N-(o-Cyanobiaryl)acrylamides with Sulfonium Salts via Synergetic Photoredox and Copper Catalysis

As the magic methyl effect is well acknowledged in pharmaceutical molecules, the development of simple and efficient methods for the installment of methyl groups on complex molecules is highly coveted. Hence, we provide a general strategy for radical cascade cyclization of N-(o-cyanobiaryl)acrylamides by utilizing sulfonium salts as the sources of methyl radical and merging photoredox and copper catalysis. This novel protocol can access a wide variety of methylation or remote thioether-substituted benzo-fused N-heterocycle derivatives, which can be easily transformed into diverse highly valuable sulfone and sulfoximine compounds via late-stage diversification. Moreover, to further demonstrate the synthetic utility of this conversion, the methyl(phenyl)sulfide, which serves as both raw material and byproduct, can be recovered and reused in this transformation. The scale-up experiment for the one-pot two-step process directly offers the target product in good yield under the standard conditions.

Dual role tertiary amines in photocatalytic cyclizations: towards sustainable syntheses of 1,3-dinitrogen heterocycles

A novel photocatalytic cascade has been engineered for the transformation of diketimines into 1,3-dinitrogen heterocycles, ingeniously repurposing methylamine a typically utilized sacrificial additive as a dual-function reagent, serving simultaneously as an electron donor and a methyl source. This innovation champions atom economy and underscores a commitment to sustainable chemical synthesis.

Molecular Engineering of Methylated Sulfone-Based Covalent Organic Frameworks for Back-Reaction Inhibited Photocatalytic Overall Water Splitting

Solar-to-hydrogen (H2) and oxygen (O2) conversion via photocatalytic overall water splitting (OWS) holds great promise for a sustainable fuel economy, but has been challenged by the backward O2 reduction reaction (ORR) with favored proton-coupled electron transfer (PCET) dynamics. Here, we report that molecular engineering by methylation inhibits the backward ORR of molecular photocatalysts and enables efficient OWS process. As demonstrated by a benchmark sulfone-based covalent organic framework (COF) photocatalyst, the precise methylation of its O2 adsorption sites effectively blocks electron transfer and increases the barrier for hydrogen intermediate desorption that cooperatively obstructs the PCET process of ORR. Methylation also repels electrons to the neighboring photocatalytic sulfone group that promotes the forward H2 evolution. The resultant DS-COF achieves an impressive inhibition of about 70 % of the backward reaction and a three-fold enhancement of the OWS performance with a H2 evolution rate of 124.7 μmol h-1 g-1, ranking among the highest reported for organic-based photocatalysts. This work provides insights for engineering photocatalysts at the molecular level for efficient solar-to-fuel conversion.

Development of Iron-Based Single Atom Materials for General and Efficient Synthesis of Amines

Earth abundant metal-based heterogeneous catalysts with highly active and at the same time stable isolated metal sites constitute a key factor for the advancement of sustainable and cost-effective chemical synthesis. In particular, the development of more practical, and durable iron-based materials is of central interest for organic synthesis, especially for the preparation of chemical products related to life science applications. Here, we report the preparation of Fe-single atom catalysts (Fe-SACs) entrapped in N-doped mesoporous carbon support with unprecedented potential in the preparation of different kinds of amines, which represent privileged class of organic compounds and find increasing application in daily life. The optimal Fe-SACs allow for the reductive amination of a broad range of aldehydes and ketones with ammonia and amines to produce diverse primary, secondary, and tertiary amines including N-methylated products as well as drugs, agrochemicals, and other biomolecules (amino acid esters and amides) utilizing green hydrogen.

β-Methylation of Primary Alcohols with Methanol Catalyzed by a Metal-Ligand Bifunctional Iridium Catalyst

The development of efficient methods for the direct introduction of a methyl group into molecules is becoming increasingly important. Herein, the β-methylation of primary alcohols with methanol has been accomplished under environmentally benign conditions using [Cp*Ir(2,2'-bpyO)(H2O)] as a catalyst. It was found that functional groups in the ligand are crucially important for the activity of the iridium complex. Furthermore, the mechanistic research and application potential of our catalytic system are also presented.

Leveraging long-lived arenium ions in superacid for meta-selective methylation

Electrophilic aromatic substitution is one of the most mechanistically studied reactions in organic chemistry. However, precluded by innate substituent effects, the access to certain substitution patterns remains elusive. While selective C-H alkylation of biorelevant molecules is eagerly awaited, especially for the insertion of a methyl group whose magic effect can boost lead molecules potency, one of the most obvious strategies would rely on electrophilic aromatic substitution. Yet, the historical Friedel-Crafts methylation remains to date poorly selective and limited to activated simple aromatics. Here, we report the development of a selective electrophilic methylation enabling the direct access to highly desirable 1,3-disubstituted arenes. This study demonstrates that this reaction is driven by the generation of long-lived arenium intermediates generated by protonation in superacid and can be applied to a large variety of functionalized (hetero)aromatics going from standard building blocks to active pharmaceutical ingredients.

Development of Brain Penetrant Pyridazine Pantothenate Kinase Activators

Conversion of pantothenate to phosphopantothenate in humans is the first dedicated step in the coenzyme A (CoA) biosynthesis pathway and is mediated by four isoforms of pantothenate kinase. These enzymes are allosterically regulated by acyl-CoA levels, which control the rate of CoA biosynthesis. Small molecule activators of the PANK enzymes that overcome feedback suppression increase CoA levels in cultured cells and animals and have shown great potential for the treatment of pantothenate kinase-associated neurodegeneration and propionic acidemias. In this study, we detail the further optimization of PANK pyridazine activators using structure-guided design and focus on the cellular CoA activation potential, metabolic stability, and solubility as the primary drivers of the structure-activity relationship. These studies led to the prioritization of three late-stage preclinical lead PANK modulators with improved pharmacokinetic profiles and the ability to substantially increase brain CoA levels. Compound 22 (BBP-671) eventually advanced into clinical testing for the treatment of PKAN and propionic acidemia.

Trideuteromethylthiolation through Reaction of Arynes, S-Methyl-d3 Sulfonothioate with Sulfonamides or Amides: Access to Trideuteromethylated Sulfilimines

A direct and practical three-component tandem reaction of arynes, S-methyl-d3 sulfonothioate with sulfonamides or amides is developed. The reaction is highly efficient and chemoselective, which allows mild synthesis of trideuteromethylated sulfilimines with broad substrate scope and good functional group compatibility, giving the products in good to excellent yields with 92%-99% deuterium incorporation. Mechanism studies disclosed sulfenamide that generated in situ is the key intermediate for the reaction. This protocol provides potential method for introduction of -SCD3 moiety for deuteration of marked drugs and drug candidates containing sulfilimine skeleton.

Site-selective α-C(sp3)-H arylation of dialkylamines via hydrogen atom transfer catalysis-enabled radical aryl migration

Site-selective C(sp3)-H arylation is an appealing strategy to synthesize complex arene structures but remains a challenge facing synthetic chemists. Here we report the use of photoredox-mediated hydrogen atom transfer (HAT) catalysis to accomplish the site-selective α-C(sp3)-H arylation of dialkylamine-derived ureas through 1,4-radical aryl migration, by which a wide array of benzylamine motifs can be incorporated to the medicinally relevant systems in the late-stage installation steps. In contrast to previous efforts, this C-H arylation protocol exhibits specific site-selectivity, proforming predominantly on sterically more-hindered secondary and tertiary α-amino carbon centers, while the C-H functionalization of sterically less-hindered N-methyl group can be effectively circumvented in most cases. Moreover, a diverse range of multi-substituted piperidine derivatives can be obtained with excellent diastereoselectivity. Mechanistic and computational studies demonstrate that the rate-determining step for methylene C-H arylation is the initial H atom abstraction, whereas the radical ipso cyclization step bears the highest energy barrier for N-methyl functionalization. The relatively lower activation free energies for secondary and tertiary α-amino C-H arylation compared with the functionalization of methylic C-H bond lead to the exceptional site-selectivity.

Polyoxymethylene Upcycling into Methanol and Methyl Groups Catalyzed by a Manganese Pincer Complex

Polyoxymethylene (POM) is a commonly used engineering thermoplastic, but its recycling by conventional means, i.e., mechanical recycling, is not practiced to any meaningful extent, due to technical limitations. Instead, waste POM is typically incinerated or disposed in landfills, where it becomes a persistent environmental pollutant. An attractive alternative to mechanical recycling is upcycling, namely, the conversion of waste POM into value-added chemicals, but this has received very little attention. Herein, we report the upcycling of POM into useful chemicals through three different reactions, all of which are efficiently catalyzed by a single pincer complex of earth-abundant manganese. One method involves hydrogenation of POM into methanol using H2 gas as the only reagent, whereas another method converts POM into methanol and CO2 through a one-pot process comprising acidolysis followed by Mn-catalyzed disproportionation. The third method utilizes POM as a reagent for the methylation of ketones and amines.

The use of methanol as a C1 building block

Methanol is a key building block in the chemical industry. In recent years, it has been used as a C1 source in various organic transformations in the presence of a transition-metal catalyst. This protocol describes the ruthenium- and cobalt-catalyzed utilization of methanol in different types of methylation reactions and heterocycle synthesis. Initially, we describe the synthesis of tridentate ligands (L1-L3) and their corresponding Ru(II) complexes (Ru-1, -2 and -3) and then detail how to apply these Ru(II) complexes and Co/PP3 (PP3 = P(CH2CH2PPh2)3) in various methanol dehydrogenative coupling reactions. We discuss six types of transformations by using methanol or a methanol/water mixture. The experimental setup for all the catalytic reactions is similar and involves adding all the respective reagents and solvents to an argon-filled pressure tube, which is sealed (by screw cap) and refluxed at the indicated temperature before the desired products are isolated and characterized. The catalytic systems described in this protocol work well for both small-scale and preparative-scale synthesis of various N-methylated amines/amides, C-methylated products and quinazolinones. These catalytic reactions are greener and more sustainable than conventional synthesis methods, with only H2 and/or H2O as by-products, and we evaluate the 'green chemistry metrics' for a typical substrate. The total time required for the catalytic experiments described in this protocol is 16-28 h, and the operation time is 4 h. An average level of expertise in organic synthesis is required to carry out these protocols.

Regio- and Enantioselective Hydromethylation of 3-Pyrrolines and Glycals Enabled by Cobalt Catalysis

Enantioenriched 3-methylpyrrolidine, with its unique chiral nitrogen-containing core skeleton, exists widely in various functional molecules, including natural products, bioactive compounds, and pharmaceuticals. Traditional methods for synthesizing these valuable methyl-substituted heterocycles often involve enzymatic processes or complex procedures with chiral auxiliaries, limiting the substrate scope and efficiency. Efficient catalytic methylation, especially in an enantioselective manner, has been a long-standing challenge in chemical synthesis. Herein, we present a novel approach for the remote and stereoselective installation of a methyl group onto N-heterocycles, leveraging a CoH-catalyzed asymmetric hydromethylation strategy. By effectively combining a commercial cobalt precursor with a modified bisoxazoline (BOX) ligand, a variety of easily accessible 3-pyrrolines can be converted to valuable enantiopure 3-(isotopic labeling)methylpyrrolidine compounds with outstanding enantioselectivity. This efficient protocol streamlines the two-step synthesis of enantioenriched 3-methylpyrrolidine, which previously required up to five or six steps under harsh conditions or expensive starting materials.

Divergent Transformations of Aromatic Esters: Decarbonylative Coupling, Ester Dance, Aryl Exchange, and Deoxygenative Coupling

ConspectusAromatic esters are cost-effective, versatile, and commonly used scaffolds that are readily synthesized or encountered as synthetic intermediates. While most conventional reactions involving these esters are nucleophilic acyl substitutions or 1,2-nucleophilic additions─where a nucleophile attacks the carbonyl group, decarbonylative transformations offer an alternative pathway by using the carbonyl group as a leaving group. This transition-metal-catalyzed process typically begins with oxidative addition of the C(acyl)-O bond to the metal. Subsequently, the reaction involves the migration of CO to the metal center, the reaction with a nucleophile, and reductive elimination to yield the final product. Pioneering work by Yamamoto on nickel complexes and the development of decarbonylative reactions (such as Mizoroki-Heck-type olefination) using aromatic carboxylic anhydrides catalyzed by palladium were conducted by de Vries and Stephan. Furthermore, reports have surfaced of decarbonylative hydrogenation of pyridyl methyl esters by Murai using ruthenium catalysts as well as Mizoroki-Heck-type reactions of nitro phenyl esters by Gooßen under palladium catalysis. Our group has been at the forefront of developing decarbonylative C-H arylations of phenyl esters with 1,3-azoles and aryl boronic acids using nickel catalysts. The key to this reaction is the use of phenyl esters, which are easy to synthesize, stabilize, and handle, allowing oxidative addition of the C(acyl)-O bond; nickel, which facilitates oxidative addition of the C(acyl)-O bond; and suitable bidentate phosphine ligands that can stabilize the intermediate. By modification of the nucleophiles, esters have been effectively utilized as electrophiles in cross-coupling reactions, encouraging the development of these nucleophiles among researchers. This Account summarizes our advancements in nucleophile development for decarbonylative coupling reactions, particularly highlighting the utilization of aromatic esters in diverse reactions such as alkenylation, intramolecular etherification, α-arylation of ketones, C-H arylation, methylation, and intramolecular C-H arylation for dibenzofuran synthesis, along with cyanation and reductive coupling. We also delve into reaction types that are distinct from typical decarbonylative reactions, including ester dance reactions, aromatic ring exchanges, and deoxygenative transformations, by focusing on the oxidative addition of the C(acyl)-O bond of the aromatic esters to the metal complex. For example, the ester dance reaction is hypothesized to undergo 1,2-translocation starting with oxidative addition to a palladium complex, leading to a sequence of ortho-deprotonation/decarbonylation, followed by protonation, carbonylation, and reductive elimination. The aromatic exchange reaction likely involves oxidative addition of complexes of different aryl electrophiles with a nickel complex. In deoxygenative coupling, an oxidative addition complex with palladium engages with a nucleophile, forming an acyl intermediate that undergoes reductive elimination in the presence of an appropriate reducing agent. These methodologies are poised to captivate the interest of synthetic chemists by offering unconventional and emerging approaches for transforming aromatic esters. Moreover, we demonstrated the potential to transform readily available basic chemicals into new compounds through organic synthesis.

Strategies for Using Quaternary Ammonium Salts as Alternative Reagents in Alkylations

Alkylation reactions are pivotal in organic chemistry, with wide-ranging utilization across various fields of applied synthetic chemistry. However, conventional reagents employed in alkylations often pose substantial health and exposure risks. Quaternary ammonium salts (QAS) present a promising alternative for these transformations offering significantly reduced hazards as they are non-cancerogenic, non-mutagenic, non-flammable, and non-corrosive. Despite their potential, their use in direct organic transformations remains relatively unexplored. This review outlines strategies for utilizing QAS as alternative reagents in alkylation reactions, providing researchers with safer approaches to chemical synthesis.

4,4-Dimethylsterols Reduces Fat Accumulation via Inhibiting Fatty Acid Amide Hydrolase In Vitro and In Vivo

4,4-Dimethylsterols constitute a unique class of phytosterols responsible for regulating endogenous cannabinoid system (ECS) functions. However, precise mechanism through which 4,4-dimethylsterols affect fat metabolism and the linkage to the ECS remain unresolved. In this study, we identified that 4,4-dimethylsterols, distinct from 4-demethseterols, act as inhibitors of fatty acid amide hydrolases (FAAHs) both in vivo and in vitro. Genetic ablation of FAAHs (faah-1) abolishes the effects of 4,4-dimethylsterols on fat accumulation and locomotion behavior in a Caenorhabditis elegans model. We confirmed that dietary intervention with 4,4-dimethylsterols in a high-fat diet (HFD) mouse model leads to a significant reduction in body weight (>11.28%) with improved lipid profiles in the liver and adipose tissues and increased fecal triacylglycerol excretion. Untargeted and targeted metabolomics further verified that 4,4-dimethylsterols influence unsaturated fatty acid biosynthesis and elevate oleoyl ethanolamine levels in the intestine. We propose a potential molecular mechanism in which 4,4-dimethylsterols engage in binding interactions with the catalytic pocket (Ser241) of FAAH-1 protein due to the shielded polarity, arising from the presence of 2 additional methyl groups (CH3). Consequently, 4,4-dimethylsterols represent an unexplored class of beneficial phytosterols that coordinate with FAAH-1 activity to reduce fat accumulation, which offers new insight into intervention strategies for treating diet-induced obesity.

Modular Approach to Highly Substituted 3-Methylpyridones

A method has been developed for the rapid synthesis of highly substituted 3-methylpyridones via the condensation of Baylis-Hillman amines and ketones under benzoic acid catalysis. The process features readily available starting materials, broad substrate scope, high functional group tolerance, excellent regioselectivity, and gram-scale synthesis. We envision that this on-demand construction of 3-methylpyridones will provide exciting opportunities in biological research, therapeutics, and material sciences.