Lactam Derivatives Research Articles

Batch vs Continuous‐Flow Method to Synthesize N‐(3‐acylamidopropyl)lactams through N‐C Bond Cleavage in Amides with Amidines

The selective N‐C bond cleavage of amides to create value‐added products through a transition metal‐free approach has become a significant challenge. Here, we present a method to convert amides into N‐(3‐acylamidopropyl)lactams through sequential amide chemoselective N‐C bond cleavage and amidine ring opening under mild conditions, applicable in batch and continuous flow processes. These methods utilize bench‐stable reagents and are operationally straightforward and mild, enabling synthesis on a gram scale with excellent functional group tolerance. Additionally, the synthetic feasibility of these reactions under flow conditions has proven to be highly efficient, providing N‐(3‐acylamidopropyl)lactam derivatives with improved yields and shorter reaction time.

N-Alkyl Isofagomine Lactams: Synthesis, Glycosidase Inhibition, and Antimicrobial Assessments

AbstractA series of six N-alkyl isofagomine lactam derivatives is synthesized over ten steps from d-arabinose. The compounds are evaluated as glycosidase inhibitors. It was found that the N-alkyl groups have a detrimental effect on the glycosidase inhibition activities, as the prepared N-alkyl isofagomine lactam derivatives are much less potent glycosidase inhibitors than native isofagomine lactam.

Synthesis and Molecular Docking Studies of New Ibuprofen Derivatives as AChE, BChE, and COX‐2 Inhibitors

AbstractAlzheimer's disease (AD), the most common age‐related neurodegenerative condition, is named after Alois Alzheimer and is marked by a progressive deterioration in memory, cognitive function, and behavior. Research has highlighted the importance of nonsteroidal anti‐inflammatory drugs (NSAIDs) in inhibiting the aggregation of amyloid β‐peptide (Aβ), a key feature of AD pathology. Ibuprofen, an NSAID from the propionic acid class, is widely used to manage osteoarthritis and rheumatoid arthritis, exhibiting strong anti‐inflammatory and antipyretic effects. However, the drug's acidic group limits its selectivity for cyclooxygenase (COX) enzymes and contributes to several adverse effects. This study aimed to modify the acidic moiety of ibuprofen into lactone (IBU‐O 1–4) and lactam (IBU‐I 1–3) derivatives to mitigate these side effects. The structural properties of the synthesized imidazolone (IBU‐I 1–3) and oxazolone (IBU‐O 1–4) derivatives were characterized through Q‐TOF LC‐MS, ¹H‐NMR, ¹3C‐NMR, and IR spectroscopy. Molecular docking studies followed by Ellman's method assessed the inhibitory effects of these compounds on acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), while an enzyme immunoassay (EIA) kit was used to evaluate their inhibition of cyclooxygenase‐2 (COX‐2).

Trans-selective carboxylative cyclization of 1,6-dienes using the CO2 radical anion

Abstract The reactivity of the carbon dioxide radical anion (CO2•−) toward alkenes has garnered remarkable attention owing to its potential to synthesize valuable organic compounds. Herein, we report the reactions between CO2•− and 1,6-dienes, yielding 5-membered lactam derivatives via highly trans-selective 5-exo-trig cyclization. Both carboxylative cyclization and hydrocyclization occur with up to 74% combined yield. Computational studies show that the transition state during cyclization favors the trans-configuration over the cis-configuration. This work offers new insights into the synthesis of N-heterocycles.

Supercritical fluid chromatographic chiral separation of potential P2RX7 antagonists containing one, two and three chiral centers

Eleven polysaccharide-based chiral stationary phases were screened to separate stereoisomers of six lactam derivatives by supercritical fluid chromatography (SFC). Those molecules are antagonists of the P2×7 receptor with potential anti-inflammatory activity. They present a mixture of either two enantiomers, or four or eight stereoisomers depending on the number of chiral centers in their structure. The effect of chiral stationary phase, either amylose- or cellulose-based, coated or immobilized, chlorinated or non-chlorinated, on retention and selectivity of those compounds was studied. The effect of the co-solvent nature (methanol, ethanol, propan-2-ol and acetonitrile) and percentage (15 to 40 %), temperature (20 to 45 °C) and backpressure (8 to 20 MPa) on the enantioseparation and retention of 1-(2-chlorobenzyl)-5-((4-methoxyphenyl)amino)pyrrolidin-2-one (compound 4) was thoroughly studied. Thus, optimal conditions were defined for each derivative in order to implement the preparative separation of the whole series, except of 1-((3,4-dimethoxyphenyl)(phenyl)methyl)-5-oxo-N-(1-phenylethyl)pyrrolidine-2-carboxamide) (compound 6) for which none of the eleven columns could resolve the eight stereoisomers. The small-scale preparative separation of the enantiomers of the most promising derivative, i.e. 3-acetyl-1-(4-chlorophenyl)-N-(2,4-dichlorobenzyl)-5-oxopyrrolidine-2-carboxamide (compound 2), is presented.

Isolation, Identification and Chemical Modification of Bufadienolides from Bufo melanostictus Schneider and Their Cytotoxic Activities against Prostate Cancer Cells.

The traditional Chinese medicine toad venom (Venenum bufonis) has been extensively used to treat various diseases, including cancers, in China and other Southeast Asian countries. The major constituents of toad venom, e.g., bufadienolides and alkaloids, exhibit broad-spectrum pharmacological effects in cancers. Herein, two new bufadienolides (1 and 2), along with eleven known compounds (3-13) were successfully isolated from Bufo melanostictus Schneider. Their structures were elucidated by extensive spectroscopic data and X-ray diffraction analysis. Furthermore, four lactam derivatives were synthesized through the transformation of bufadienolides lactones. The inhibitory effects of these compounds against human prostate cancer cell lines PC-3 and DU145 were evaluated. The outcomes indicated a notable trend, with a substantial subset displaying nanomolar range IC50 values against PC-3 and DU145 cells, underscoring their pronounced cytotoxicity. Moreover, a noteworthy distinction surfaces, wherein lactones consistently outperformed their lactam counterparts, further validating their heightened potency for the treatment of prostate cancer. This study contributes significant preclinical evidence substantiating the therapeutic viability of bufadienolides and toad venom as intervention strategies for prostate cancer.

Chemical constituents of <i>Citrus grandis</i> (L.) Osbeck (Rutaceae) and their α-glucosidase inhibitory activity

The chemical investigation of the methanolic bark extract of <i>Citrus grandis</i> (L.) Osbeck (Rutaceae) led to the isolation of one saponin named aridanin (<b>1</b>) isolated for the first time in the genus <i>Citrus</i>, together with seventeen known compounds including eight acridone-type alkaloids, two limonoids, two coumarins, one sugar, one lactam derivative, and three common steroids. Their structures were conclusively established using 1D- and 2D-NMR spectral data. The isolated compounds 1-9 were tested for their α-glucosidase inhibitory activity and the results showed that they all have potency higher than the reference acarbose (IC<sub>50</sub> = 218.2 ± 2.8 μM) and aridanin was the strongest one which could be due to its sugar unit as usually observed for triterpene saponins. Furthermore, the structure-activity relationship of the tested compounds has been discussed as well as the chemotaxonomic significance of the study. The present study enriches the chemistry of <i>Citrus</i> with three additional compounds (1, 14, 15) and classifies the plant <i>C. grandis</i> as a good source of leads for the development of anti-diabetic drugs.

Fulvanines J-K, two rare lactam pyrrole alkaloids from Hemerocallis fulva.

Two rare jatropham lactam derivatives, named as fulvanines J-K (1-2), together with six known pyrrole alkaloids, 5,5'-oxydi(3-methyl-3-pyrrolin-2-one) (3), (-)-5-hydroxy-3-methyl-3-pyrrolin-2-one (jatropham) (4), (±)-5-O-methyljatropham (5), perlolyrine (6), butyl-2-formyl-5-(hydroxymethyl)-1H-pyrrole-1-butanoate (7), and hemerocallisamine II (8), were isolated from the flower of Hemerocallis fulva. Their structures were elucidated on the basis of spectroscopic methods and compared with the NMR spectra data in the literature. All compounds were evaluated for their anti-complementary activity in vitro, and compounds 1, 4, and 6 exhibited anti-complement effect with CH50 values from 0.61 to 1.42 mM.

A mechanistic study of chiral manganese porphyrin-catalyzed enantioselective C-H hydroxylation reaction.

We employed density functional theory (DFT) calculations to elucidate the mechanism and origin of enantioselectivity in the C-H hydroxylation reaction catalyzed by a chiral manganese porphyrin complex. Our study reveals that the chiral manganese porphyrin forms a two-point hydrogen bonding interaction with the substrate. Specifically, the hydrogen atom abstraction of the methylene pro-(S) C-H bond at the heterocyclic C-3 position is 1.9 kcal mol-1 favored over the hydrogen atom abstraction of the pro-(R) C-H bond. This preferential reactivity results in the predominant formation of (S)-hydroxylated products. Our DFT calculations are consistent with the experimental findings of high enantioselectivity in the chiral manganese porphyrin catalyzed C(sp3)-H hydroxylation of lactam derivatives. The observed enantioselectivity arises from the formation of two-point hydrogen bonding between lactam derivatives and manganese porphyrin catalysts. Moreover, our computations indicate varying degrees of substrate distortion upon attack by high-valent manganese oxygen complexes at different hydrogen atoms.

Visible-light-mediated substituent-controlled regiodivergent (2 + 2)/(3 + 2) cycloadditions for the synthesis of aza-analogs of β-lactam and γ-fused lactam derivatives

Substituent-controlled regiodivergent synthesis of aza-analogs of β-lactam and γ-fused lactam derivatives via the visible-light-induced Wolff rearrangement of α-diazoketones and azo esters.

Ring Expansion Reactions through Intramolecular Transamidation

AbstractSynthetic methodologies based on cycle expansion reactions have proven to be highly effective in delivering valuable medium‐sized cycles and macrocycles. A primary method of ring expansion relies on intramolecular transamidation reactions. These reactions typically employ N‐aminoalkyl and N‐aminoacyl derivatives of lactams and their analogues as starting materials, yielding a diverse spectrum of unique nitrogen‐containing heterocycles.This Review aims to provide a comprehensive analysis of the research outcomes related to intramolecular transamidation reactions that lead to cycle expansion. This will offer the reader a perspective on the potential applications of such reactions in generating novel and intriguing types of heterocyclic systems.

Two New Lactam Derivatives from Micromelum falcatum (Lour.) Tan. with Brine Shrimp Larvae Toxicity.

Chemical investigation of the stems of Micromelum falcatum (Lour.) Tan. led to the isolation of two new lactam derivatives, named 3-(hydroxy(10-hydroxyphenyl)methyl)-4-(16-hydroxyphenyl)-1-methylpyrrolidin-2-one (1) and 3-(hydroxy(10-hydroxy-9-methoxyphenyl)methyl)-4-(16-hydroxyphenyl)-1-methylpyrrolidin-2-one (2), along with five known compounds, trans-4-hydroxycinnamic acid (3), 4-hydroxybenzaldehyde (4), m-hydroxybenzoic acid (5), p-hydroxybenzoic acid (6), and gallic acid (7). Their structures were determined on the basis of spectroscopic studies, including nuclear magnetic resonance (NMR) spectrum, mass spectrometry (MS) data, ultraviolet (UV) spectrum, infrared (IR) data, and comparison with the literature. All compounds were evaluated for toxicity against brine shrimp larvae and cytotoxicity to HeLa and HepG-2 cells. Compounds 1-2 exhibited moderate brine shrimp larvae toxicity with an LC50 value of 50.6 and 121.8 μg mL-1, respectively.

2D QSAR, Design, and in Silico Analysis of Thiophene-Tethered Lactam Derivatives as Antimicrobial Agents.

A very high rate of resistance causes health-care-associated and community-acquired infections. E. coli is one of the nine pathogens of highest concern to most of the antibiotics and other class of antimicrobials. The objective of the present study is to develop novel thiophene derivatives using 2D QSAR and in silico approach for E. coli resistance. Substituted thiophene series reported by Nishu Singla et al., were taken for QSAR analysis. From the results, a set of 15 new compounds were designed. A complete in silico analysis has been done using PADEL, Autodock vina, Swiss ADME, Protox II software. The designed compounds obey the Lipinski's rule of five and were known to have excellent inhibitory action (pIC50 values -0.87 to -1.46) which is similar to the most active compound of the data set (pIC50 -0.69) taken for the study. The bioavailability score (0.65) with no toxicity representing that the designed compounds are suitable for oral administration. The designed compounds are inactive for mutagenicity and cytotoxicity and ADMET studies states that these molecules are likely to be orally bioavailable and could be easily transported, diffused, and absorbed. So, the designed compounds will definitely serve as a lead antibacterial agent for E. coli resistance.

Structural diversification of phenylspirodrimane lactams by employing a biosynthetic intermediate

Phenylspirodrimanes are a kind of meroterpenoids with structural diversity and complexity, exhibiting a wide of biological properties, especially for the lactam derivatives consisting a γ-lactam moiety and N-linked side chains. These compounds were derived from multi-step combination of enzymatic and non-enzymatic conversions of intermediates in their biosynthetic pathways. Stachbotrydial (2) with an o-phthalaldehyde unit was supposed as the high-reactivity intermediate of phenylspirodrimane lactams via nonenzymatic reaction with amines. In the present work, an effective and non-enzymatic diversification strategy was developed for the structural diversification of phenylspirodrimane lactams including monomers and dimers from 2 by feeding structurally various mono- and diamines in the fungus Stachybotrys chartarum cultures. In total, 24 phenylspirodrimane lactams (1, 3–25) including 18 new compounds were synthesized. Among them, stachybocin A (1), a bioactive phenylspirodrimane lactam dimer, was produced with the yield of 18.7 mg/g of cell dry weight. The structures of these compounds were elucidated by extensive spectroscopic data, single-crystal X-ray diffraction (Cu Kα), and calculated electronic circular dichroism (ECD) analyses. Bioassay revealed that compounds 1, 17, and 24 displayed significant inhibitory effect on the inactivated state of hNaV 1.2 channels with IC50 values of 0.22, 2.08, and 0.53 µmol/L, respectively. In addition, 1 showed potent protein tyrosine phosphatase 1B (PTP1B) inhibitory, N-methyl-d-aspartate (NMDA) receptor antagonistic, and anti-inflammatory activities.

Ring expansion reactions of PO-containing molecules.

A series of ring expansion reactions of PO-containing molecules have been developed for the synthesis of medium-sized ring cyclic phosphonate esters and phosphonamidates. The reactivity trends initially appear to be counter-intuitive, compared with more well established ring expansion reactions of lactam derivatives, but are explained by considering the differences in heteroatom bonding to P and C respectively.

Two new lactam derivatives from a Sphagneticola trilobata derived fungus Penicillium rubens PQJ-2

A new bicyclic lactam derivatives penicilactam B (1) and a new monocyclic amide penicillamide D (2), along with four known compounds (3-6), were isolated from the fermentation broth of the derived fungus Penicillium rubens PQJ-2. Their structures and stereochemistry were elucidated by comprehensive spectroscopic analyses and quantum ECD calculations. All the compounds were evaluated for their antibacterial activities against Staphylococcus aureus subsp, Candida albicans, Escherichia coli and insecticidal activity against Helicoverpa armigera Hubner. Compounds 1-3 exhibited modest insecticidal activity against H. armigera Hubner.

α‐Angelica Lactone Catalyzed Oxidation of Pyrrolidines to Lactams

α‐Angelica Lactone Catalyzed Oxidation of Pyrrolidines to Lactams

Synthesis of Hydroxylated Polycyclic Pyrrolo/Indolo[1,2-a]quinoxaline-Fused Lactam Derivatives via PhI(OAc)2-Promoted 1,2-Bond Migration and Solvent Insertion.

PhI(OAc)2-mediated ring expansion via 1,2-bond migration and concurrent solvent insertion generate hydroxylated polycyclic pyrrolo/indolo[1,2-a]quinoxaline-fused lactam derivatives in a highly diastereoselective fashion from spiro-fused quinoxalines in good-to-excellent yield. X-ray crystal structure analysis reveals that the polycyclic lactams are nonplanar molecules devoid of any symmetry as they possess one or two axially chiral biaryl or N-arylindolyl bridges along with one chiral center at the bridgehead carbon.

Designing, antifungal and structure activity relationship studies of Azomethines and β-lactam derivatives of aza heterocyclic amines

The present investigation deals with the synthesis of seven azomethine derivatives 1–7 of aza heterocyclic amines by carrying out condensation reaction of them with veratraldehyde followed by cyclizing the CHN moiety in synthesized azomethines of 4-amino-1,2,4-triazole and 4-amino antipyrine to yield β lactam derivatives 8–9. The chemical constituents in the synthesized compounds were confirmed by UV, IR, 1H NMR, 13C NMR, and elemental analysis. In vitro antifungal activity of all the synthesized products was done against four pathogenic maize fungal strains i.e. Fusarium verticillioides, Macrophomina phaseolina, Rhizoctonia solani, and Dreschlera maydis. It was found that azomethine derivative having 4-amino-1,2,4-triazole ring was as effective as standard carbendazim 50 WP against R. solani and may be considered as promising antifungal agent; therefore further modifications may be done in its structure to get better drug candidate in future.

Design and Synthesis of Bi‐aryl Methylated Lactam Derivatives to Inhibit the BRD7 Bromodomain Function in Prostate Cancer

Targeting bromodomain‐containing proteins has emerged as a promising therapeutic strategy and multiple clinical studies indicate that bromodomain (BD) inhibitors can act as anticancer and anti‐inflammatory agents. Bromodomain‐containing protein 7 (BRD7) is a subunit of the SWI/SNF chromatin remodeling complex, which is involved in the fine‐tuning of gene expression through changes in the organization of DNA. It regulates the progression of different types of cancers such as nasopharyngeal carcinoma and hormone‐dependent breast and ovarian cancers. BRD7 is also implicated in progression of prostate cancer, another hormone‐dependent malignancy; however, the role of BRD7 in this type of cancer is undefined. (Figure 1) We have characterized BRD7 as an oncogenic driver across a variety of prostate cancer cell lines, implicating BRD7 inhibitors as a potential therapeutic strategy to combat therapy resistant cancers.To develop inhibitors of BRD7 we are developing small molecules that bind selectively to the bromodomain of BRD7. The main challenge when developing BRD7 BD inhibitors is the high similarity to the BRD9 BD, its closest homolog. Several dual inhibitors of BRD7 and BRD9 have been developed, all of them being more selective for the BRD9 BD over the BRD7 BD. Using the X‐ray crystal structure of both BDs bound to a BRD9‐selective inhibitor, we identified an accessible hydrophobic region in the binding pocket of BRD7 that is not present in BRD9, which we hypothesized could be exploited to develop BRD7‐selective inhibitors. Based on this structural difference in the BRD7 binding pocket, we designed a library of compounds that share a bi‐aryl methylated lactam core. (Figure 2)From in silicomolecular docking simulations and in vitro affinity screenings, we have identified several ligands selective for BRD7. These compounds also display potent anti‐proliferative effects in prostate cancer cell lines, providing further evidence for proposing BRD7 as a therapeutic target in prostate cancer. Our on‐going work focuses on optimizing the potency and solubility properties of BRD7 inhibitors, and characterizing their selectivity using cell‐based models.