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Alkylamine structures represent one of the most functional and widely used in organic synthesis and drug design. However, the general methods for the functionalization of the shielded and deshielded alkyl radicals remain elusive. Here, we report a general deoxygenative amination protocol using alcohol-derived carbazates and nitrobenzene under electrochemical conditions. A range of primary, secondary, and tertiary alkylamines are obtained. This practical procedure can be scaled up through electrochemical continuous flow technique. Secondary arylalkylamines represent important building blocks for organic synthesis, and as such their straightforward synthesis from readily available chemicals remains a priority in organic chemistry. Here, the authors report a synthesis of arylalkylamines from nitroarenes and carbazates via paired electrolysis. [ABSTRACT FROM AUTHOR]

In the realm of organic and green chemistry, the functionalization of cyclobutanes presents a significant challenge, given their unique structural properties and biological relevance. Particularly, the introduction of difluoromethyl groups into cyclobutane frameworks is a burgeoning area of interest due to their potential in drug design and synthesis. However, the construction of difluoromethyl cyclobutanes heavily relies on the environmentally burdensome fluorination of cyclobutyl ketones. Methods to efficiently and directly introduce difluoromethyl groups into cyclobutanes remain underexplored. This study introduces a novel photochemical protocol for the selective difluoromethylation or bromo difluoromethylation of bicyclobutanes, leveraging green solvent-controlled reactions. Remarkably, this method exhibits the merits of both green chemistry and organic chemistry such as renewable visible light as reaction power, high atom economy and fully controlled chemo-selectivity. This work also reveals the mechanism behind the remarkable selectivity achieved. Emphasizing the importance of difluoromethyl cyclobutane scaffolds as bioisosteres, this research not only broadens the chemical space in organic synthesis but also offers new avenues for pharmaceutical discovery. The findings demonstrate the robustness and versatility of the method, including its applicability to drug modifications, addressing a crucial gap in the green synthesis of complex medicinal molecules. [ABSTRACT FROM AUTHOR]

Automating retrosynthesis with artificial intelligence expedites organic chemistry research in digital laboratories. However, most existing deep-learning approaches are hard to explain, like a "black box" with few insights. Here, we propose RetroExplainer, formulizing the retrosynthesis task into a molecular assembly process, containing several retrosynthetic actions guided by deep learning. To guarantee a robust performance of our model, we propose three units: a multi-sense and multi-scale Graph Transformer, structure-aware contrastive learning, and dynamic adaptive multi-task learning. The results on 12 large-scale benchmark datasets demonstrate the effectiveness of RetroExplainer, which outperforms the state-of-the-art single-step retrosynthesis approaches. In addition, the molecular assembly process renders our model with good interpretability, allowing for transparent decision-making and quantitative attribution. When extended to multi-step retrosynthesis planning, RetroExplainer has identified 101 pathways, in which 86.9% of the single reactions correspond to those already reported in the literature. As a result, RetroExplainer is expected to offer valuable insights for reliable, high-throughput, and high-quality organic synthesis in drug development. Automating retrosynthesis prediction in organic chemistry is a major application of ML. Here the authors present RetroExplainer, which offers a high-performance, transparent and interpretable deep-learning framework providing valuable insights for drug development. [ABSTRACT FROM AUTHOR]

In recent years, the activation of unactivated alkyl chlorides through light-induced processes has emerged as a promising field in radical chemistry, and has led to new transformations in organic synthesis. Direct utilization of alkyl chlorides as C(sp3)-hybridized electrophiles enables the facile construction of carbon–carbon and carbon–heteroatom bonds. Furthermore, recent studies in medicinal chemistry indicate that their presence is associated with high levels of success in clinical trials. This review summarizes the recent advances in the photoinduced activation of unactivated alkyl chlorides and discusses the mechanistic aspects underlying these reactions. We anticipate that this review will serve as a valuable resource for researchers in the field of unactivated chemical bond functionalization, and inspire considerable developments in organic chemistry, drug synthesis, materials science and other related disciplines. [ABSTRACT FROM AUTHOR]

Benzimidazoles and their derivatives play an extraordinarily significant role as therapeutic agents, e.g., antiulcer, analgesic, and anthelmintic drugs. The organic synthesis of benzimidazoles and derivatives to obtain active pharmacological compounds represents an important research area in organic chemistry. The use of non-environmental organic compounds and application high energy synthetic methods, the production of waste, and the application of conventional toxic processes are a problem for the pharmaceutical industry and for these important drugs' synthesis. The substituted benzimidazoles are summarized in this review to provide insight about their organic synthesis using ecofriendly methods, as well as their pharmacological activities. [ABSTRACT FROM AUTHOR]

The discovery of the Domino reaction offers a useful strategy to the scientific community. From the beginning, it has received much attention in numerous advances for organic synthesis. Especially, for the constructive cyclization via multiple C−C and C‐heteroatom bond formation, the Domino‐Heck coupling reaction has become an essential tool in organic chemistry. In the case of drug synthesis, different natural products and biologically relevant scaffolds are achieved by employing the Domino‐cyclization technique. Palladium or nickel‐based intramolecular coupling reactions have been associated with many developing methods which lead to important carbo or heterocyclic scaffolds. In this account, metal‐catalyzed intramolecular cyclization is an emerging tool to access several heterocyclic scaffolds such as coumarins, quinolines, piperidines, indoles spiro and fused polycyclic rings. In this review, we have attempted to highlight the recent advances in metal‐mediated Domino cyclization reaction over the past few years. [ABSTRACT FROM AUTHOR]

Aromatic nitro compounds play a unique role in the synthesis of drugs and pharmaceutically oriented molecules. This field of organic chemistry continues to be in demand and relevant. A significant number of papers are published annually on new general methods for the synthesis of nitrodrugs and related biomolecules. This review is an analysis of the literature on methods for the synthesis of both new and already-known aromatic and heteroaromatic nitrodrugs covering the period from 2010 to the present. [ABSTRACT FROM AUTHOR]

Continuous-flow chemistry has become a mainstream process and a notable trend among emerging technologies for drug synthesis. It is routinely used in academic and industrial laboratories to generate a wide variety of molecules and building blocks. The advantages it provides, in terms of safety, speed, cost efficiency and small-equipment footprint compared to analog batch processes, have been known for some time. What has become even more important in recent years is its compliance with the quality objectives that are required by drug-development protocols that integrate inline analysis and purification tools. There can be no doubt that worldwide government agencies have strongly encouraged the study and implementation of this innovative, sustainable and environmentally friendly technology. In this brief review, we list and evaluate the development and applications of continuous-flow processes for antibiotic synthesis. This work spans the period of 2012–2022 and highlights the main cases in which either active ingredients or their intermediates were produced under continuous flow. We hope that this manuscript will provide an overview of the field and a starting point for a deeper understanding of the impact of flow chemistry on the broad panorama of antibiotic synthesis.

Allosteric modulation of G protein-coupled receptors (GPCRs) is nowadays a hot topic in medicinal chemistry. Allosteric modulators, i.e., compounds which bind in a receptor site topologically distinct from orthosteric sites, exhibit a number of advantages. They are more selective, safer and display a ceiling effect which prevents overdosing. Allosteric modulators of dopamine D2 receptor are potential drugs against a number of psychiatric and neurological diseases, such as schizophrenia and Parkinson’s disease. In this review, an insightful summary of current research on D2 receptor modulators is presented, ranging from their pharmacology and structural aspects of ligand-receptor interactions to their synthesis.

Majority of drugs act by interacting with chiral counterparts, e.g., proteins, and we are, unfortunately, well-aware of how chirality can negatively impact the outcome of a therapeutic regime. The number of chiral, non-racemic drugs on the market is increasing, and it is becoming ever more important to prepare these compounds in a safe, economic, and environmentally sustainable fashion. Asymmetric organocatalysis has a long history, but it began its renaissance era only during the first years of the millennium. Since then, this field has reached an extraordinary level, as confirmed by the awarding of the 2021 Chemistry Nobel Prize. In the present review, we wish to highlight the application of organocatalysis in the synthesis of enantio-enriched molecules that may be of interest to the pharmaceutical industry and the medicinal chemistry community. We aim to discuss the different activation modes observed for organocatalysts, examining, for each of them, the generally accepted mechanisms and the most important and developed reactions, that may be useful to medicinal chemists. For each of these types of organocatalytic activations, select examples from academic and industrial applications will be disclosed during the synthesis of drugs and natural products.

Ubiquitous α,β‐unsaturated esters are well recognized as key structural olefin scaffolds in organic chemistry. (E)‐ and (Z)‐steroselectivity is the most critical issue in their synthesis, however, (E)‐ and (Z)‐ stereocomplementary synthetic methods remain quite limited. The present account discloses general (E)‐, (Z)‐stereocomplementary syntheses of a variety of α,β‐unsaturated esters from highly accessible (E)‐, (Z)‐stereodefined enol tosylates derived from β‐ketoesters and α‐formyl esters. Step 1 toward the stereocomplementary preparation of (E)‐, (Z)‐stereodefined enol tosylates is implemented by using inexpensive reagents under mild reaction conditions. Step 2 toward the highly stereoretentive synthesis of (E)‐ and (Z)‐stereodefined α,β‐unsaturated esters involves Suzuki‐Miyaura, Negishi, Sonogashira, Iron‐catalyzed, Mizoroki‐Heck, and Buchwald‐Hartwig cross‐coupling reactions. Notably, this strategy was successfully applied for parallel drug syntheses of (E)‐ and (Z)‐zimelidine, (E)‐ and (Z)‐tamoxifen, and Merck's cyclopropane pharmacophore. Representative successful utilizations by other groups are also introduced. [ABSTRACT FROM AUTHOR]

The development of facile, efficient, cost‐effective, and visible light‐driven photocatalysts for organic synthetic chemistry has received increasing attention. This protocol has initially synthesized a naphthalimide‐based ND‐O‐EAc visible light photocatalyst for the sulfonation of alkenes to produce β‐ketosulfones. Compared with the current photosynthetic strategies, the newly developed catalytic system has some merits, namely high efficiency, gram‐scale preparation of low‐cost photocatalyst, no metal contamination, wide substrate scope, and green terminal oxidant of air. Moreover, the prepared photocatalyst of ND‐O‐EAc is feasible for the sulfonation reactions of androstenones. Importantly, such a photocatalysis strategy can easily realize the scale‐up synthesis for β‐ketosulfone drugs under the mild conditions up to 90 % yield. [ABSTRACT FROM AUTHOR]

Continuous flow chemistry is by now an established and valued synthesis technology regularly exploited in academic and industrial laboratories to bring about the improved preparation of a variety of molecular structures. Benefits such as better heat and mass transfer, improved process control and safety, a small equipment footprint, as well as the ability to integrate in-line analysis and purification tools into telescoped sequences are often cited when comparing flow to analogous batch processes. In this short review, the latest developments regarding the exploitation of continuous flow protocols towards the synthesis of anticancer drugs are evaluated. Our efforts focus predominately on the period of 2016–2021 and highlight key case studies where either the final active pharmaceutical ingredient (API) or its building blocks were produced continuously. It is hoped that this manuscript will serve as a useful synopsis showcasing the impact of continuous flow chemistry towards the generation of important anticancer drugs.

Anthraquinone (AQ) derivatives play a prominent role in medicine and also in textile industry. Bromaminic acid (1-amino-4-bromoanthraquinone-2-sulfonic acid) is an important precursor for obtaining dyes as well as biologically active compounds through the replacement of the C4-bromo substituent with different (ar)alkylamino residues. Here we report methods for the synthesis of bromaminic acid analogues bearing different substituents at the 2-position of the anthraquinone core. 1-Aminoanthraquinone was converted to its 2-hydroxymethyl-substituted derivative which, under different reaction conditions, yielded the corresponding carbaldehyde, carboxylic acid, and nitrile derivatives. The latter was further reacted to obtain 1-amino-2-tetrazolylanthraquinone. Subsequent bromination using bromine in DMF led to the corresponding bromaminic acid derivatives in excellent isolated yields (>90%) and high purities. Alternatively, 1-amino-4-bromo-2-hydroxymethylanthraquinone could be directly converted to the desired 2-substituted bromaminic acid analogues in high yields (85–100%). We additionally report the preparation of bromaminic acid sodium salt and 1-amino-2,4-dibromoanthraquinone directly from 1-aminoanthraquinone in excellent yields (94–100%) and high purities. The synthesized brominated AQs are valuable precursors for the preparation of AQ drugs and dyes.

For an advanced-level module associated with designing drug syntheses, a set of homework tasks were created to help students prepare for their exam. Students were asked to solve the next case study as homework, effectively writing the next lecture's notes in advance of the session using requisite knowledge and moderate instructor guidance. Students found these activities effective at preparing them for the exam, increasing their subject knowledge and confidence towards unseen synthesis problems. [ABSTRACT FROM AUTHOR]

Aldose reductase (ALR2) inhibition is the most legitimate approach for the management of diabetic complications. The limited triumph in the drug development against ALR2 is mainly because of its close structural similarity with the other members of aldo-keto reductase (AKR) superfamily viz. ALR1, AKR1B10; and lipophilicity problem i.e. poor diffusion of synthetic aldose reductase inhibitors (ARIs) to target tissues. The literature evidenced that naturally occurring curcumin demonstrates relatively specific and non-competitive inhibition towards human recombinant ALR2 over ALR1 and AKR1B10; however β-diketone moiety of curcumin is a specific substrate for liver AKRs and accountable for it’s rapid in vivo metabolism. In the present study, structure based comprehensive modelling studies were used to map the pharmacophoric features/spatial fingerprints of curcumin analogues responsible for their ALR2 specificity along with potency on a data set of synthetic curcumin analogues and naturally occurring curcuminoids. The data set molecules were also screened for drug-likeness or ADME parameters, and the screening data strongly support that curcumin analogues could be proposed as a good drug candidate for the development of ALR2 inhibitors with improved pharmacokinetic profile compared to curcuminoids due to the absence of β-diketone moiety in their structural framework. [ABSTRACT FROM AUTHOR]

The first step of the benzoxazinoid (BX) synthesis pathway is catalyzed by an enzyme with indole-3-glycerol phosphate lyase activity encoded by 3 genes, Bx1, TSA and Igl. A gene highly homologous to maize and wheat Bx1 has been identified in rye. The goal of the study was to analyze the gene and to experimentally verify its role in the rye BX biosynthesis pathway as a rye ortholog of the Bx1 gene. Expression of the gene showed peak values 3 days after imbibition (dai) and at 21 dai it was undetectable. Changes of the BX content in leaves were highly correlated with the expression pattern until 21 dai. In plants older than 21 dai despite the undetectable expression of the analyzed gene there was still low accumulation of BXs. Function of the gene was verified by correlating its native expression and virus-induced silencing with BX accumulation. Barley stripe mosaic virus (BSMV)-based vectors were used to induce transcriptional (TGS) and posttranscriptional (PTGS) silencing of the analyzed gene. Both strategies (PTGS and TGS) significantly reduced the transcript level of the analyzed gene, and this was highly correlated with lowered BX content. Inoculation with virus-based vectors specifically induced expression of the analyzed gene, indicating up-regulation by biotic stressors. This is the first report of using the BSMV-based system for functional analysis of rye gene. The findings prove that the analyzed gene is a rye ortholog of the Bx1 gene. Its expression is developmentally regulated and is strongly induced by biotic stress. Stable accumulation of BXs in plants older than 21 dai associated with undetectable expression of ScBx1 indicates that the function of the ScBx1 in the BX biosynthesis is redundant with another gene. We anticipate that the unknown gene is a putative ortholog of the Igl, which still remains to be identified in rye. [ABSTRACT FROM AUTHOR]

A review of the recent literature is given focusing on synthetic approaches to 1,2,3,4-tetrahydroquinolines, 2,3-dihydro-4(1H)-quinolinones and 4(1H)-quinolinones using domino reactions. These syntheses involve: (1) reduction or oxidation followed by cyclization; (2) SNAr-terminated sequences; (3) acid-catalyzed ring closures or rearrangements; (4) high temperature cyclizations and (5) metal-promoted processes as well as several less thoroughly studied reactions. Each domino method is presented with a brief discussion of mechanism, scope, yields, simplicity and potential utility.

Integrative, research-based experiences have shown tremendous potential as effective pedagogical approaches. Pharmaceutical development is an exciting field that draws heavily on organic chemistry and biochemistry techniques. A capstone drug synthesis/analysis laboratory is described where biochemistry students synthesize azo-stilbenoid compounds and test the biological activity of those compounds as well as a known inhibitor on mushroom tyrosinase using UV/vis-based kinetic assays. In this paper, three such successful azo-stilbenoid inhibitors of tyrosinase, representative student generated data, technical aspects of the experiments, and an interpretation of student feedback on the project as a whole are presented. [ABSTRACT FROM AUTHOR]

We report a novel series of quinoxaline derivatives from which agents with antiproliferative activity have been identified. Two ethyl 3-(arylethynyl)quinoxaline-2-carboxylates demonstrated substantial antiproliferative activity against both human non-small cell lung carcinoma (A549) and glioblastoma (U87-MG) cell lines. Pyrido[4,3- b ]quinoxalin-1(2 H )-ones demonstrated poor activity against A549 and U87-MG cell lines. Three of the derivatives in ethyl 3-(arylethynyl)quinoxaline-2-carboxylate series demonstrated substantial antiproliferative activity. The arylethynyl derivative 2a and 2d proved to be the most cytotoxic with an IC 50 value of 3.3 μM for both A549 and U87-MG cell lines. [ABSTRACT FROM AUTHOR]

The chemical synthesis of new lipophilic polyphenols with improved properties presents technical difficulties. Here we describe the selection, isolation and identification of lipolytic bacteria from food-processing industrial wastes, and their use for tailoring a new set of compounds with great interest in the food industry. These bacteria were employed to produce lipolytic supernatants, which were applied without further purification as biocatalysts in the chemoselective and regioselective synthesis of lipophilic partially acetylated phenolic compounds derived from olive polyphenols. The chemoselectivity of polyphenols acylation/deacylation was analyzed, revealing the preference of the lipases for phenolic hydroxyl groups and phenolic esters. In addition, the alcoholysis of peracetylated 3,4-dihydroxyphenylglycol resulted in a series of lipophilic 2-alkoxy-2-(3,4-dihydroxyphenyl)ethyl acetate through an unexpected lipase-mediated etherification at the benzylic position. These new compounds are more lipophilic and retained their antioxidant properties. This approach can provide access to unprecedented derivatives of 3,4-dihydroxyphenylglycol with improved properties. [ABSTRACT FROM AUTHOR]

A synthesis of the R,R-tartrate salt of the popular anti-Parkinson's drug R-rasagiline (Azilect) was adapted to introduce the organic laboratory student to a medically relevant synthesis. It makes use of concepts found in the undergraduate organic chemistry curriculum, appropriately fits into three approximately 4 h lab periods, and utilizes readily available equipment and inexpensive commercially available chemicals. [ABSTRACT FROM AUTHOR]

As part of an effort to profile potential therapeutics for the treatment of inflammation-related diseases, a diversity of amide-linked small molecules was synthesized by using parallel synthesis strategy. Moreover, these new compounds were also evaluated for their inhibitory effects on nitric oxide (NO) by using tumor necrosis factor alpha (TNF-α)-induced inflammatory responses in chondrocytes. Among the tested compounds, N-(3-chloro-4-fluorophenyl)-2-hydroxybenzamide (HS-Ck) was the most potent inhibitor of NO production and inducible nitric oxide synthase (iNOS) expression in TNF-α-stimulated chondrocytes. In addition, our biological results indicated that HS-Ck might suppress the expression levels of iNOS and matrix metalloproteinases-13 (MMP-13) activities through downregulating the activation of nuclear factor kappa B (NF-κB) and signal transducer and activator of transcription 3 (STAT-3) transcriptional factors. Therefore, the parallel synthesis was successful used to develop a new class of potential anti-inflammatory agents as chondroprotective candidates for the treatment of osteoarthritis. [ABSTRACT FROM AUTHOR]

It has been reported that inhibition of RAD52 either by specific shRNA or a small peptide aptamer induced synthetic lethality in tumor cell lines carrying BRCA1 and BRCA2 inactivating mutations. Molecular docking was used to screen two chemical libraries: 1) 1,217 FDA approved drugs, and 2) 139,735 drug-like compounds to identify candidates for interacting with DNA binding domain of human RAD52. Thirty six lead candidate compounds were identified that were predicted to interfere with RAD52 –DNA binding. Further biological testing confirmed that 9 of 36 candidate compounds were able to inhibit the binding of RAD52 to single-stranded DNA in vitro. Based on molecular binding combined with functional assays, we propose a model in which the active compounds bind to a critical “hotspot” in RAD52 DNA binding domain 1. In addition, one of the 9 active compounds, adenosine 5’-monophosphate (A5MP), and also its mimic 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) 5’ phosphate (ZMP) inhibited RAD52 activity in vivo and exerted synthetic lethality against BRCA1 and BRCA2–mutated carcinomas. These data suggest that active, inhibitory RAD52 binding compounds could be further refined for efficacy and safety to develop drugs inducing synthetic lethality in tumors displaying deficiencies in BRCA1/2-mediated homologous recombination. [ABSTRACT FROM AUTHOR]

This series of three practical sessions centers on drugs that inhibit the enzyme acetylcholineesterase. This enzyme is responsible for the inactivation of acetylcholine and has been the target of drugs to treat glaucoma and Alzheimer's disease and for a number of insecticides and warfare agents. These sessions relate to a series of carbamate inhibitors that are classed as slowly reversible anticholinesterases and show how structure--activity relationships can guide the development of drug molecules. In Practical 1, each student group synthesizes one carbamate inhibitor of acetylcholinesterase. In Practical 2, students measure the activity of their inhibitor to derive an IC50 value suitable for comparison with the other derivatives made by the class. In Practical 3, students gain firsthand experience with structure--activity methods, such as a Hansch analysis, to investigate whether these can be used to make predictions of the activity of related compounds based on structural properties. This series gives students a rare insight into a number of the important aspects of drug discovery, that of drug synthesis, activity testing, and the construction of subsequent quantitative structure--activity relationships (QSARs). [ABSTRACT FROM AUTHOR]

A drug discovery project has been successfully implemented in a first-year general, organic, and biochemistry (GOB) health science course and second-year organic undergraduate chemistry course. This project allows students to apply the fundamental principles of chemistry and biology to a problem of medical significance, practice basic laboratory skills, and understand the interdisciplinary aspect of the drug discovery platform. Students collectively synthesize a small library of antituberculosis compounds and subsequently screen them using a Kirby--Bauer disc diffusion assay for inhibitory activity against Mycobacterium smegmatis, a known safe surrogate of Mycobacterium tuberculosis, the causative agent of tuberculosis. The last unit of the project involves students using PyMOL, a free computer program, to examine a cocrystal structure of the activated inhibitor--enzyme complex, allowing students to identify the molecular interactions responsible for the binding affinity. [ABSTRACT FROM AUTHOR]

A series of novel N-(furan-2-yl)-1-(5-substituted) phenyl-1,3,4-oxadiazol-2-yl) methanimines (Fa-e) were synthesized and evaluated for antitubercular activity against Mycobacterium tuberculosis (H37Rv) strain by using alamar blue assay. The synthesized compounds were characterized based on IR, HMR and mass spectral analysis. The toxicity profile was predicted by organic chemistry portal, a web based application for predicting in silico absorption, distribution, metabolism, excretion and toxicity, and the novel derivatives under study did not show any toxicity issues. The mechanism of action of the titled derivatives was predicted by docking on the Mycobacterium tuberculosis Enoyl-ACP reductase enzyme. The docking study concluded that Fb and Fa possessed good binding energy indicating more prominent interaction towards the active sites NAD and TYR 158. The antitubercular studies showed that the both Fa and Fb possessed significant activity with the MIC as low as 3.125 µg/ml. [ABSTRACT FROM AUTHOR]