Morpholine Ring Research Articles

Reevaluation of fenpropimorph as a σ receptor ligand: Structure-affinity relationship studies at human σ1 receptors

Fenpropimorph (1) is considered a “super high-affinity” σ1 receptor ligand (Ki=0.005nM for guinea pig σ1 receptors). Here, we examine the binding of 1 and several of its deconstructed analogs at human σ1 (hσ1) receptors. We monitored their subtype selectivity by determining the binding affinity at σ2 receptors. In addition, we validated an existing pharmacophore model at the molecular level by conducting 3D molecular modeling studies, using the crystal structure of hσ1 receptors, and Hydrophatic INTeractions (HINT) analysis. Our structure affinity relationship studies showed that 1 binds with lower affinity at hσ1 receptors (Ki=17.3nM) compared to guinea pig; moreover, we found that none of the fenpropimorph methyl groups is important for its binding at hσ1 receptors, nor is stereochemistry. For example, removal of all methyl groups as seen in 4 resulted in an almost 5-fold higher affinity at hσ1 receptors compared to 1 and 350-fold selectivity versus σ2 receptors. In addition, although the O atom of the morpholine ring does not contribute to affinity at hσ1 receptors (and might even detract from it), it plays role in subtype (σ1 versus σ2 receptor) selectivity.

Effects of structural modification of the daunosamine moiety of anthracycline antibiotics on pKa values determined by capillary zone electrophoresis.

The thermodynamic acid dissociation constants (pKa1 and pKa2) of 16 anthracycline antibiotics, including doxorubicin (DOX) and daunorubicin (DAU), their epimers, epidoxorubicin (EDOX) and epidaunorubicin (EDAU), as well as novel anthracycline derivatives containing piperidine (FPIP), morpholine (FMOR) and hexamethylenoimine (FHEX) rings in the formamidine group of the daunosamine moiety were determined by analysis of the dependence between measured electrophoretic mobility and the pH of the buffer using the capillary zone electrophoresis method. The results obtained confirmed the ampholytic character of anthracyclines with at least two ionization states. The determined values were in the range of 8.36-9.28 and 9.38-11.48 for pKa1 and pKa2 arising from ionization of amino and phenolic groups, respectively. Structural modifications in the daunosamine moiety of the studied anthracyclines affected their pharmacological properties, such as antiproliferative activity.

Unified Synthesis of 1,2-Oxy-aminoarenes via a Bio-inspired Phenol-Amine Coupling

Summary 1,2-Aminophenols and their related nitrogen-containing heterocycles are ubiquitous in medicine, agriculture, and materials science. Here, we describe a bio-inspired and unified approach for their synthesis through a direct, catalytic aerobic coupling of phenols and amines. Key to the formation of the aromatic C–N bond is a facile condensation between the amine and an ortho -quinone, which triggers redox isomerization to an ortho -iminophenol before a series of downstream events. We discuss the factors that govern regioselectivity during aerobic ortho -oxygenation of the phenol and condensation of the amine, and we demonstrate synthetic utility by preparing a structurally diverse family of immunosuppressive heterocycles and the indole alkaloid cephalandole A. Our conditions involve a wide range of simple, un-activated substrates, occur at room temperature with an earth-abundant copper-catalyst and a commercially available diamine ligand, and produce water as the only stoichiometric by-product.

Poly(N,N-diallylazacycloalkane)s for Anion-Exchange Membranes Functionalized with N-Spirocyclic Quaternary Ammonium Cations

The alkaline stability of organic cations tethered to anion-exchange membranes (AEMs) is essential for the long-term performance of alkaline membrane fuel cells and electrolyzers. Here, we have prepared and studied the thermal and alkaline stability of a series of polyelectrolytes functionalized with N-spirocyclic quaternary ammonium (QA) cations. N,N-Diallylazacycloalkane quaternary salts were readily synthesized by diallylation of pyrrolidine, piperidine, azepane, and morpholine. These monomers were employed in radical-initiated cyclo-polymerizations to obtain the target poly(N,N-diallylazacycloalkane)s. 1H NMR spectroscopy revealed that the stability of the polyelectrolytes in 2 M KOD/D2O solutions critically depended on the ring size and the absence of additional heteroatoms in the ring. Thus, poly(N,N-diallylpiperidinium) showed the highest alkaline stability, with only minor signs of degradation at 120 °C after 14 days, while the polyelectrolytes based on the morpholine and azepane rings clearly deg...

Studies of CDK 8/19 inhibitors: Discovery of novel and selective CDK8/19 dual inhibitors and elimination of their CYP3A4 time-dependent inhibition potential

In this article, synthetic studies around a pyridylacrylamide-based hit compound (1), utilizing structure-based drug design guided by CDK8 docking models, is discussed. Modification of the pendant 4-fluorophenyl group to various heteroaromatic rings was conducted aiming an interaction with the proximal amino acids, and then replacement of the morpholine ring was targeted for decreasing potential of time-dependent CYP3A4 inhibition. These efforts led to the compound 4k, with enhanced CDK8 inhibitory activity and no apparent potential for time-dependent CYP3A4 inhibition (CDK8 IC50: 2.5nM; CYP3A4 TDI: 99% compound remaining). Compound 4k was found to possess a highly selective kinase inhibition profile, and also showed favorable pharmacokinetic profile. Oral administration of 4k (15mg/kg, bid. for 2weeks) suppressed tumor growth (T/C 29%) in an RPMI8226 mouse xenograft model.

4-Chloro-5-(morpholin-4-yl)-2-[(5-phenyl-1,3,4-oxadiazol-2-yl)methyl]pyridazin-3(2H)-one

In the title compound, C17H16ClN5O3, the phenyl and the oxadiazole rings are almost coplanar, subtending a dihedral angle of 4.34 (19)°. These rings lie almost normal to the pyridazine ring, making dihedral angles of 87.35 (16) and 89.06 (15)°, respectively. The morpholine ring has the usual chair conformation and its mean plane is inclined to the pyridazine ring by 39.45 (17)°. There is a short intramolecular C—H...Cl contact present. In the crystal, molecules are linked by bifurcated C—(H,H)...O hydrogen bonds and a C—H...N hydrogen bond, forming layers parallel to the ab plane.

De Novo Assembly of Highly Substituted Morpholines and Piperazines.

The morpholine and piperazine with their remarkable physical and biochemical properties are popular heterocycles in organic and medicinal chemistry used in rational property design. However, in the majority of cases these rings are added to an existing molecule in a building block approach thus limiting their substitution pattern and diversity. Here we introduce a versatile de novo synthesis of the morpholine and piperazine rings using multicomponent reaction chemistry. The large scale amenable building blocks can be further substituted at up to four positions, making this a very versatile scaffold synthesis strategy. Our methods thus fulfill the increasing demand for novel building block design and nontraditional scaffolds which previously were not accessible

Rifamorpholines A-E, potential antibiotics from locust-associated actinobacteria Amycolatopsis sp. Hca4.

Cultivation of locust associated rare actinobacteria, Amycolatopsis sp. HCa4, has provided five unusual macrolactams rifamorpholines A-E. Their structures were determined by interpretation of spectroscopic and crystallographic data. Rifamorpholines A-E possess an unprecedented 5/6/6/6 ring chromophore, representing a new subclass of rifamycin antibiotics. The biosynthetic pathway for compounds 1-5 involves a key 1,6-cyclization for the formation of the morpholine ring. Compounds 2 and 4 showed potent activities against methicillin-resistant Staphylococcus aureus (MRSA) with MICs of 4.0 and 8.0 μM, respectively.

In vivo anti-inflammatory activity and docking study of newly synthesized benzimidazole derivatives bearing oxadiazole and morpholine rings

In search of potential therapeutics for inflammatory disease, we report herein the synthesis, characterization and anti-inflammatory activities of a new series of 1-{(5-substituted-1,3,4-oxadiazol-2-yl)methyl}-2-(morpholinomethyl)-1H-benzimidazoles (5a-r). The anti-inflammatory activity of the compounds was evaluated using carrageenan induced rat paw edema test. Some compounds showed excellent anti-inflammatory activity in carrageenan induced rat paw edema test. 1-{(5-(2-Chlorophenyl)-1,3,4-oxadiazol-2-yl)methyl}-2-(morpholinomethyl)-1H-benzimidazole (5g) showed maximum anti-inflammatory (74.17±1.28% inhibition) with reduced ulcerogenic and lipid peroxidation profile and also showed significant COX-2 inhibition with IC50 values of 8.00μM. Compounds 5o and 5q were also found to exhibit good COX-2 inhibition with IC50 values of 11.4 and 13.7μM concentrations. Molecular docking study showed that morpholine and oxadiazole rings linked to the benzimidazole nucleus play an important role in binding with the COX-2.

Design, synthesis and biological evaluation of novel azaspiro analogs of linezolid as antibacterial and antitubercular agents

The design, synthesis and antimicrobial evaluation of a novel series of azaspiro analogues of linezolid (1) have been described. Linezolid comprises of a morpholine ring which is known for its metabolism-related liabilities. Therefore, the key modification made in the linezolid structure was the replacement of morpholine moiety with its bioisostere, 2-oxa-6-azaspiro[3.3]heptane. Furthermore, the replacement of N-acetyl terminal of 1 with various aromatic or aliphatic functionalities was carried out. The title compounds were evaluated against a panel of Gram-positive and Gram-negative bacteria and Mycobacterium tuberculosis. Subsequent structure-activity relationship (SAR) studies identified several compounds with mixed antibacterial and antitubercular profiles. Compound 22 (IC50 0.72, 0.51, 0.88, 0.49 μg/mL for Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis, respectively) exhibited similar antibacterial profile as 1. The N-acetyl derivative 18 was similar to 1 in antitubercular profile. Thus, the present study successfully demonstrated the use of azaspiro substructure in the medicinal chemistry of antibacterial and antitubercular agents.

Discovery and antiplatelet activity of a selective PI3Kβ inhibitor (MIPS-9922)

A series of amino-substituted triazines were developed and examined for PI3Kβ inhibition and anti-platelet function. Structural adaptations of a morpholine ring of the prototype pan-PI3K inhibitor ZSTK474 yielded PI3Kβ selective compounds, where the selectivity largely derives from an interaction with the non-conserved Asp862 residue, as shown by site directed mutagenesis. The most PI3Kβ selective inhibitor from the series was studied in detail through a series of in vitro and in vivo functional studies. MIPS-9922, 10 potently inhibited ADP-induced washed platelet aggregation. It also inhibited integrin αIIbβ3 activation and αIIbβ3 dependent platelet adhesion to immobilized vWF under high shear. It prevented arterial thrombus formation in the in vivo electrolytic mouse model of thrombosis without inducing prolonged bleeding or excess blood loss.

Absorption, distribution, metabolism and elimination of 14C-ETX0914, a novel inhibitor of bacterial type-II topoisomerases in rodents

1. ETX0914 is a novel bacterial topoisomerase inhibitor that has a novel mode-of-inhibition and is in clinical development for the treatment of infections caused by Neisseria gonorrhoeae.2. The in vitro biotransformation studies of ETX0914 using mouse, rat, dog and human hepatocytes showed moderate intrinsic clearance in mouse and rat and low intrinsic clearance in dog and human.3. Following intravenous administration of [14C]-ETX0914 in rats, the mean recovery of administered dose in urine, bile and feces was approximately 15%, 55% and 24%, respectively. Unchanged ETX0914 recovered in urine and bile was less than 5% of the dose, indicating that ETX0914 underwent extensive metabolism in rats. Metabolites M1, M2, M4, M6 and M12 detected in both rat and mouse urine samples were not detected in mouse urine when predosed with 1-aminobenzotriazole, indicating that these metabolites were cytochrome P450 mediated products. The major fecal metabolites observed in rats were not formed when ETX0914 was incubated with fresh feces from germ free rats under sterile condition or in incubations with rat intestinal microsome and cytosol, suggesting that most likely ETX0914 was directly excreted into gut lumen where metabolites were formed as intestinal microflora-mediated products. The major sites of metabolism by CYP enzymes were in the morpholine and oxazolidinone rings while it was benzisoxazole reduction with the gut microflora.

Discovery of 2-(3,4-dichlorophenoxy)-N-(2-morpholin-4-ylethyl)acetamide: A selective σ1 receptor ligand with antinociceptive effect.

Compound 2-(3,4-dichlorophenoxy)-N-(2-morpholin-4-ylethyl)acetamide (1) was designed, prepared and the in vitro binding evaluation against σ1 and σ2 receptors was measured. Compound 1 showed high σ1 receptor affinity (Ki=42 nM) and it was 36-times more selective for σ1 than σ2 receptor. Also, it was performed a molecular docking of compound 1 into the ligand binding pocket homology model of σ1 receptor, showing a salt bridge between the ionized morpholine ring and Asp126, as well as important short contacts with residues Tyr120, His154 and Trp164. Ligand efficiency indexes and predicted toxicity analysis revealed an excellent intrinsic quality of 1. The antinociceptive effect of compound 1 was determined using the formalin test. The ipsilateral local peripheral (10-300 μg/paw) and intrathecal (100 μg/rat) administration of 1 produced a reduction in formalin-induced nociception. The in vivo results indicated that 1 may be effective in treating inflammatory pain.

(5,7-Dimethyl-2-oxo-2H-chromen-4-yl)methyl morpholine-4-carbodithioate

In the title compound, C17H19NO3S2, the 2H-chromene ring system is nearly planar, with a maximum deviation of 0.080 (2) Å, and the morpholine ring adopts a chair conformation. The bond-angle sum at the N atom is 358°. The coumarin unit makes dihedral angle of 86.34 (9)° with the morpholine ring. A short intramolecular C—H...S contact generates anS(7) ring. In the crystal, inversion dimers linked by pairs of weak C—H...O hydrogen bonds generateR22(16) loops. Aromatic π–π interactions interactions [shortest centroid–centroid distance = 3.8599 (13) Å] also occur.

Toxicokinetics of new psychoactive substances: plasma protein binding, metabolic stability, and human phase I metabolism of the synthetic cannabinoid WIN 55,212-2 studied using in vitro tools and LC-HR-MS/MS.

The new psychoactive substance WIN 55,212-2 ((R)-(+)-[2,3-dihydro-5-methyl-3-(4-morpholinylmethyl)pyrrolo-[1,2,3-de]-1,4-benzoxazin-6-yl]-1-napthalenylmethanone) is a potent synthetic cannabinoid receptor agonist. The metabolism of WIN 55,212-2 in man has never been reported. Therefore, the aim of this study was to identify the human in vitro metabolites of WIN 55,212-2 using pooled human liver microsomes and liquid chromatography-high resolution-tandem mass spectrometry (LC-HR-MS/MS) to provide targets for toxicological, doping, and environmental screening procedures. Moreover, a metabolic stability study in pooled human liver microsomes (pHLM) was carried out. In total, 19 metabolites were identified and the following partly overlapping metabolic steps were deduced: degradation of the morpholine ring via hydroxylation, N- and O-dealkylation, and oxidative deamination, hydroxylations on either the naphthalene or morpholine ring or the alkyl spacer with subsequent oxidation, epoxide formation with subsequent hydrolysis, or combinations. In conclusion, WIN 55,212-2 was extensively metabolized in human liver microsomes incubations and the calculated hepatic clearance was comparably high, indicating a fast and nearly complete metabolism in vivo. This is in line with previous findings on other synthetic cannabinoids. Copyright © 2016 John Wiley & Sons, Ltd.

(7, 8-Dimethyl-2-oxo-2H-chromen-4-yl)methyl morpholine-4-carbodithioate

In the title compound, C17H19NO3S2, the chromene unit makes a dihedral angle of 88.48 (5)° with the best plane through the morpholine ring. The carbodithioate group is present in an antiperiplanar conformation with respect to the morpholine ring, as indicated by the S—C—N—C torsion angle of −171.64 (8)°. The morpholine moiety adopts the usual chair conformation. The crystal structure features C—H...O and C—H...S hydrogen bonds and C—H...π interactions.

Morpholine-4-carboxamidinium sulfate

The asymmetric unit of the title salt, 2C5H12N3O+·SO42−, comprises two cations and one sulfate ion. In both cations, the C, N and O atoms of the morpholine rings are disordered over two sets of sites, with refined occupancies of 0.849 (3):0.151 (3) for cation I and 0.684 (4):0.316 (4) for cation II. The C—N bond lengths in both central C3N units of the carboxamidinium ions range between 1.253 (12) and 1.362 (5) Å, indicating a degree of double-bond character. The central C atoms are bonded to the three N atoms in a nearly ideal trigonal–planar geometry and the positive charges are delocalized in both CN3planes. The crystal structure is stabilized by a three-dimensional network of N—H...O hydrogen bonds between the cations and the sulfate ion. Scheme tiny font, charges and delocalized bonds almost invisible

An integrated molecular modeling approach for in silico design of new tetracyclic derivatives as ALK inhibitors

Anaplastic lymphoma kinase (ALK), a promising therapeutic target for treatment of human cancers, is a receptor tyrosine kinase that instigates the activation of several signal transduction pathways. In the present study, in silico methods have been employed in order to explore the structural features and functionalities of a series of tetracyclic derivatives displaying potent inhibitory activity toward ALK. Initially docking was performed using GLIDE 5.6 to probe the bioactive conformation of all the compounds and to understand the binding modes of inhibitors. The docking results revealed that ligand interaction with Met 1199 plays a crucial role in binding of inhibitors to ALK. Further to establish a robust 3D-QSAR model using CoMFA and CoMSIA methods, the whole dataset was divided into three splits. Model obtained from Split 3 showed high accuracy ( of 0.700 and 0.682, of 0.971 and 0.974, of 0.673 and 0.811, respectively for CoMFA and CoMSIA). The key structural requirements for enhancing the inhibitory activity were derived from CoMFA and CoMSIA contours in combination with site map analysis. Substituting small electronegative groups at Position 8 by replacing either morpholine or piperidine rings and maintaining hydrophobic character at Position 9 in tetracyclic derivatives can enhance the inhibitory potential. Finally, we performed molecular dynamics simulations in order to investigate the stability of protein ligand interactions and MM/GBSA calculations to compare binding free energies of co-crystal ligand and newly designed molecule N1. Based on the coherence of outcome of various molecular modeling studies, a set of 11 new molecules having potential predicted inhibitory activity were designed.

Solvation of the morpholinium cation in acetonitrile. Effect of an anion.

Ionic liquids (ILs) constitute a fast growing class of compounds finding multiple applications in science and technology. Morpholinium-based ILs (MBILs) and their mixtures with polar molecular co-solvents are interesting as sustainable electrolyte systems for electrochemistry. We investigate local structures of protic and apropic morpholinium cations in acetonitrile (ACN) using semi-empirical molecular dynamics (MD) simulations. An impact of an anion (acetate) on the cation solvation regularities is discussed. Unlike oxygen, nitrogen of the morpholine ring is a strong electrophilic binding center. This site is responsible for the interactions of the cation with the solvent and with the anion. In protic MBILs, the role of nitrogen is delegated to the proton, which is linked to nitrogen. The acetate anion weakens solvation of the cation due to occupation of space near nitrogen or proton. The analysis reveals a favorable solvation of MBILs in ACN, which is a prerequisite for a new high-performance electrolyte system. The reported structural data were validated through point-to-point comparison with the MP2 post-Hartree-Fock theory and density functional theory.

Crystal structure of (7-fluoro-2-oxo-2H-chromen-4-yl)methyl morpholine-4-carbodi-thio-ate.

In the title compound, C15H14FNO3S2, the 2H-chromene ring system is close to being planar (r.m.s. deviation = 0.024 Å) and the morpholine ring adopts a chair conformation. The dihedral angle between the 2H-chromene ring system and the morpholine ring (all atoms) is 88.21 (11)°. In the crystal, inversion dimers linked by pairs of very weak C—H⋯F hydrogen bonds generate R 2 2(8) loops; C—H⋯O hydrogen bonds connect the dimers into [010] chains. Weak aromatic π–π stacking inter­actions between the pyran rings of the chromene systems [centroid–centroid distance = 3.6940 (16) Å] are also observed.