Morpholine Derivatives Research Articles

New Strategy for the Synthesis of Morpholine Cores: Synthesis from N-Propargylamines

Functionalized morpholines have attracted much attention due to their potential biological activities. Despite the wide importance of morpholine derivatives in drug design of various pharmacological agents, the development of new approaches to their synthesis remains relatively unexplored. Given the low cost and easy availability of N-propargylamines, the synthesis of functionalized morpholines from these versatile building blocks have undergone an explosive growth in recent years. This review provides a concise overview of the synthesis of morpholine cores from N-propargyalamines in recent years.

Synthesis and Characterisation of Bridged Morpholine Derivatives Fused to a Phenanthrene Ring System

The synthesis of conformationally restricted and facially biased bridged morpholine derivatives fused to a phenanthrene ring system was prepared in a three-step sequence involving: (i) Voight rearrangement; (ii) stereoselective reduction of ketone and (iii) iodine mediated cyclisation, the α-allyl-α-hydroxy-ketones gave the corresponding bridged N-substituted morpholines. One of the bridged morpholine derivatives fused to a phenanthrene ring system was optically active. The NMR spectral analysis and theoretical studies show that substitution on nitrogen prefers exo-orientation, possibly to avoid steric interactions with the phenanthrene moiety.

Energetic effects of alkyl groups (methyl and ethyl) on the nitrogen of the morpholine structure

A thermochemical study of N-methylmorpholine and N-ethylmorpholine compounds was performed with the purpose of evaluating and understanding the energetic effects inherent to the replacement of the hydrogen of the amino group by an alkyl group in the morpholine scaffold. Calorimetric techniques complemented by computational calculations were used to determine the standard molar enthalpies of formation, in the gaseous phase, at T = 298.15 K, of the two morpholine derivatives. Static bomb combustion calorimetry and vacuum drop microcalorimetric techniques were used. Computational calculations of the enthalpies of hypothetical reactions in the gaseous phase, using the G3(MP2)//B3LYP composite method, were performed for the two morpholine derivatives. The values of the experimental and computational gas-phase enthalpy of formation obtained for N-alkylmorpholine compounds will be compared and discussed. The energetic effect and the structural changes resulting from the substitution of the hydrogen of the amino group by an alkyl group in the morpholine scaffold are analyzed.

The NK-1 receptor antagonist L-732,138 induces apoptosis in human gastrointestinal cancer cell lines.

Gastric and colon cancer cells express the neurokinin-1 receptor (NK-1R) and the peptide substance P (SP), after binding to this receptor, elicits the proliferation of gastrointestinal cancer cells and an antiapoptotic effect. In these cells, NK-1R antagonists (L-733,060: a piperidine derivative; aprepitant: a morpholine derivative) block, after binding to the NK-1R, the action of SP and exert an antiproliferative action, both antagonists promote apoptosis and the death of cancer cells. However, it is currently unknown whether tryptophan derivative NK-1R antagonists (e.g., L-732,138) exert an antiproliferative effect against gastrointestinal cancer cells. L-732,138, L-733,060 and aprepitant being structurally unrelated compounds show a high specificity for the NK-1R. To determine the number of viable cells, a Coulter counter was performed. For evaluation of tumor cell viability, an MTS colorimetric method was conducted. For apoptosis, a DAPI stain was carried out. L-732,138 blocked, in a concentration-dependent manner, the proliferation of gastrointestinal cancer cells (IC50: 75.28 and IC100: 127.4 for human SW-403 colon carcinoma cell line; IC50: 76.8 and IC100: 157.2 for 23132-87 gastric carcinoma cell line. Level of significance: p≤0.01). The antitumor effect elicited by L-732,138 was via the NK-1R and, in addition, 72.1% and 59.3% apoptotic cells (chromatin condensation and nuclear fragmentation) were respectively found in gastric and colon cancer cell lines when L-732,138 (at IC100 concentration) was administered. It seems that the NK-1R is an emerging drug target for the treatment of gastrointestinal cancer and that the tryptophan derivative NK-1R antagonist L-732,138 must be considered as an anticancer drug in gastrointestinal cancer.

Single‐Step Modular Synthesis of Unsaturated Morpholine N‐Oxides and Their Cycloaddition Reactions

A single-flask procedure for the generation of α-keto-N-alkenylnitrones through a Chan-Lam coupling and subsequent spontaneous 6π electrocyclization of these intermediates for the synthesis of 2H-1,4-oxazine N-oxides has been developed for a variety of α-ketooximes and alkenylboronic acids. This transformation provides a new approach to C-substituted unsaturated morpholine derivatives that are poised to undergo further functionalization for the preparation of a diverse array of novel heterocyclic structures. The scope of the new method for the synthesis of 2H-1,4-oxazine N-oxides is discussed, in addition to initial studies describing the cycloaddition reactivity of these new heterocyclic intermediates.

Single‐Step Modular Synthesis of Unsaturated Morpholine N‐Oxides and Their Cycloaddition Reactions

AbstractA single‐flask procedure for the generation of α‐keto‐N‐alkenylnitrones through a Chan–Lam coupling and subsequent spontaneous 6π electrocyclization of these intermediates for the synthesis of 2H‐1,4‐oxazine N‐oxides has been developed for a variety of α‐ketooximes and alkenylboronic acids. This transformation provides a new approach to C‐substituted unsaturated morpholine derivatives that are poised to undergo further functionalization for the preparation of a diverse array of novel heterocyclic structures. The scope of the new method for the synthesis of 2H‐1,4‐oxazine N‐oxides is discussed, in addition to initial studies describing the cycloaddition reactivity of these new heterocyclic intermediates.

Experimental and In-Silico Investigation of Anti-Microbial Activity of 1-Chloro-2-Isocyanatoethane Derivatives of Thiomorpholine, Piperazine and Morpholine.

The Antibiogram properties of 1-chloro-2-isocyanatoethane derivatives of thiomorpholine (CTC), piperazine (CPC) and morpholine (CMC) were evaluated by the approved agar well diffusion, the minimum inhibitory concentration (MIC) and in silico techniques. A total of fourteen microbial cultures consisting of ten bacteria and four yeast strains were used in the biological study while affinity of the compounds for DNA gyrase, a validated antibacterial drug target, was investigated by docking method. Results indicate that both thiomorpholine and piperazine had zero activity against the Gram negative organisms tested. With morpholine, similar result was obtained except that cultures of Escherichia coli (ATCC 15442) and Salmonella typhi (ATCC 6539) presented with weak sensitivity (7–8 mm) as shown by the inhibition zone diameter (IZD) measurement. The Gram positive organisms were more sensitive to morpholine than the other compounds. The highest IZD values of 15–18 mm were achieved except for Streptococcus pneumoniae (ATCC 49619) in which mobility of the compound stopped after 12 mm. S. pneumoniae was resistant to both thiomorpholine and piperazine. The yeast strains were not sensitive to any of the studied compounds investigated. The MIC tests evaluated against a reference antibiotic show that while morpholine was most active at 4 μg.ml-1 against both B. cereus ATCC (14579) and B. subtilis, the least active compound was thiomorpholine which inhibited S. aureus (ATCC 25923) at 64 μg.ml-1. The three compounds demonstrated high affinity for the target protein (DNA gyrase) ranging from -4.63 to -5.64 Kcal/mol and even showed better ligand efficiencies than three known antibiotics; chlorobiocin, ciprofloxacin and tetracycline. This study identified the studied compounds as potential antibiotic leads with acceptable physicochemical properties and gave the molecular basis for the observed interactions between the compounds and the target protein which can be harnessed in structural optimization process.

Dithiocarbamates effectively inhibit the β-carbonic anhydrase from the dandruff-producing fungus Malassezia globosa

A series of dithiocarbamates (DTCs) was investigated for the inhibition of the β-class carbonic anhydrase (CAs, EC 4.2.1.1) from the fungal parasite Malassezia globosa, MgCA, a validated anti-dandruff drug target. These DTCs incorporate various scaffold, among which those of N,N-dimethylaminoethylenediamine, the aminoalcohols with 3–5 carbon atoms in their molecule, 3-amino-quinuclidine, piperidine, morpholine and piperazine derivatives, as well as phenethylamine and its 4-sulfamoylated derivative. Several DTCs resulted more effective in inhibiting MgCA compared to the standard sulfonamide drug acetazolamide (KI of 74μM), with KIs ranging between 383 and 6235nM. A computational approach, involving a homology modeling of the enzyme and docking inhibitors within its active site, helped us rationalize the results. This study may contribute to better understand the inhibition profile of MgCA, and offer new ideas for the design of modulators of activity which belong to less investigated chemical classes, thus potentially useful to combat dandruff and other fungal infections.

Computer-Free Group-Addition Method for pKa Prediction of 73 Amines for CO2 Capture

The pKa value of an amine aqueous solution is directly related to the rate of its chemical reaction with CO2. A quick and accurate pKa predicted method can provide a shortcut for efficient screening of CO2 absorbents. The original and updated Perrin–Dempsey–Serjeant (PDS) pencil-and-paper group-addition methods were used to predict the pKa. The errors in pKa predictions of some cyclic, tertiary, and multihydroxy amine solutions were larger than that of the linear primary and secondary amines whether the original PDS or the updated PDS method was used. Another computer-free group-addition method (called QSSG) was proposed to predict the pKa values of 73 CO2-relevant alkanolamines/amines and cyclic amines, including piperazine and morpholine derivatives. Intramolecular hydrogen-bonding, hyperconjugation, solvent, and steric effects were analyzed. Six extra parameters were added, and 10 parameters were changed to improve the accuracy of the predicted pKa values, based on a linear free energy relationship, of...

In silico investigation of morpholines as novel class of trypanosomal triosephosphate isomerase inhibitors

Human African trypanosomiasis, also known as sleeping sickness, is caused by the single-celled kinetoplastid parasite Trypanosoma brucei transmitted to humans by infected tsetse flies. The disease threatens millions of people. Currently available treatment options are faced with some important challenges. In this work, a total of eighty-seven (87) morpholine derivatives were evaluated for drug-likeness based on Lipinski’s rule of five and their ability to inhibit the activities of trypanosomal triosephosphate isomerase was assessed by molecular docking and calculation of free energy of binding. Analysis of the results revealed that 97.7 % of the dataset complied with Lipinski’s criteria for a molecule to be orally bioavailable. Also, 50.0 % of the studied compounds had a good total polar surface area profile, a parameter which is of great importance for the treatment of stage two Trypanosoma infections. Docking studies showed that all the dataset demonstrated affinity for triosephosphate isomerase. Moreover, six morpholines scored higher than the co-crystallized inhibitor of triosephosphate isomerase (2-phosphoglycerate). These derivatives inhibited the activity of triosephosphate isomerase by making significant interactions with Glu 167, Val 214, 233, Asn 11, Lys 13, Ser 213, Leu 232, Ile 172, Gly 211, 212, 234, 235 and His 92 in the active site of the protein. Furthermore, besides the acceptable pharmacokinetic profiles of the six morpholines, they also showed inhibitory potencies toward four other validated antitrypanosomal drug targets. In view of the foregoing findings, we propose that the six morpholine derivatives be given worthwhile attention to develop them into novel trypanocides.

Synthesis of Chiral Azabicycles from Pyroglutaminols

The stereocontrolled synthesis of a range of substituted bicyclic morpholine and piperazine derivatives is reported from substituted pyroglutaminols via an intramolecular SN2 cyclization as the key step. This enantiospecific approach toward chiral bicyclic morpholines and piperazines offers new opportunities to access these challenging ring systems, which are becoming increasingly common motifs in drug discovery.

The synthesis of N-[4-methyl(41-chlorophenyl)-2-R-phenylіmіnothіazol-3-yl]-morpholine derivatives by Hantzsch reaction

The synthesis of N-[4-methyl(41-chlorophenyl)-2-R-phenylіmіnothіazol-3-yl]-morpholine derivatives by Hantzsch reaction

Approach for the Synthesis of Potent Antimicrobials Containing Pyrazole, Pyrimidine and Morpholine Analogues

The present study is in the interest of some synthesized novel derivatives containing 4-(1,3-diphenyl-1H-pyrazol-4-yl)-N-(morpholinomethyl)-6-arylpyrimidin-2-amines pooled with different bio-active heterocycles such as pyrazole, pyrimidine and morpholine derivatives. The structures of newly synthesized compounds were elucidated by IR, 1H NMR, 13C NMR and mass spectral data. The synthesized compounds were evaluated for their in vitro antimicrobial activity against different bacterial and fungal strains using Mueller-Hinton Broth dilution method. On the basis of SAR studies, it was observed that the presence of electron withdrawing groups remarkably enhanced the antimicrobial activity of synthesized compounds.

Approach for the Synthesis of Potent Antimicrobials Containing Pyrazole, Pyrimidine and Morpholine Analogues

The present study is in the interest of some synthesized novel derivatives containing 4-(1,3-diphenyl-1H-pyrazol-4-yl)-N-(morpholinomethyl)-6-arylpyrimidin-2-amines pooled with different bio-active heterocycles such as pyrazole, pyrimidine and morpholine derivatives. The structures of newly synthesized compounds were elucidated by IR, 1H NMR, 13C NMR and mass spectral data. The synthesized compounds were evaluated for their in vitro antimicrobial activity against different bacterial and fungal strains using Mueller-Hinton Broth dilution method. On the basis of SAR studies, it was observed that the presence of electron withdrawing groups remarkably enhanced the antimicrobial activity of synthesized compounds.

Synthesis and Characterization of Some New Morpholine Derivatives

In this paper a new series of morpholine derivatives was prepared by reacting the morpholine with ethyl chloro acetate in the presence triethylamine as a catalyst in benzene gave morpholin-N-ethyl acetate(1) which reacted with hydrazine hydrate in ethanol, and gave morpholin-N-ethyl acetohydrazide (2) . Morpholin-N-aceto semithiocarbazide (3) were prepared by reacting compound(2) with ammonium thiocyanate , concentrated hydrochloric acid and ethanol as a solvent .Compound (3) reacted with sodium hydroxide and hydrochloric acid to give 5-(morpholin-N-methylene)-1H-1,2,4-triazole-3-thiol (4) .The new series of 1,2,4-triazol derivatives (5-8) was synthesized by reaction of compound(4) with formaldehyde , DMF as a solvent and different secondary amines. Preparation of new 1,2,4-triazoline derivatives (9) by reaction compound (4) with bromo acetic acid . Reaction of compound (9) with different aromatic aldehyde and dimethyl sulfoxide as a solvent obtained compounds (10-13).

Synthesis of enantiomerically pure [14 C]-labelled morpholine derivatives for a class of trace amine-associate receptor 1 agonists.

Various agonists of the trace amine-associate receptor 1, under consideration as potential clinical development candidates, were labelled with carbon-14 for use in preclinical in vitro and in vivo drug metabolism studies. Herein, the [14 C]-radiosynthesis of 2-phenyl-substituted morpholines 1 is described. After evaluating and optimizing different synthetic routes, 4-iodonitrobenzene 3 was selected as starting material for the 14-step synthesis. Incorporation of carbon-14 into the acetyl moiety allowed a safe and efficient synthesis of [14 C]-labelled 4-nitroacetophenone 2 in five steps and 38% yield. Further transformation of 2 to the target compounds 1 was achieved in a 9-step synthesis. In a representative example, [14 C]-labelled 1 was obtained in an overall yield of 11% and was isolated in >99% radiochemical purity and a specific activity of 47 mCi/mmol.

Synthesis and biological screening for cytotoxic activity of N-substituted indolines and morpholines

Development of novel anticancer drugs is inevitable to improve treatment of cancers. In this study, novel derivatives of indoline and morpholine were synthesized and tested for their cytotoxic effects on osteosarcoma and Human Embryonic Kidney cells. To characterize cytotoxicity and the mechanism of cell death, we used cytotoxicity, migration, apoptosis markers and mitochondrial calcium assays. Among the compounds tested, the indoline derivatives, generally, produced a higher cytotoxic effect compared to the morpholine derivatives, in osteosarcoma cells. Specifically, new indoline derivative N-(2-hydroxy-5-nitrophenyl(4′-methylphenyl)methyl)indoline exhibited effective cytotoxic activity, with an IC50 of ∼74 μM. The same molecule induced cell death by apoptosis and inhibited migration of the cells. Further, analysis of mitochondrial calcium levels revealed the existence of calcium dependent cell death mechanisms in different cell types. Therefore, N-(2-hydroxy-5-nitrophenyl(4′-methylphenyl)methyl)indoline can be considered as a potential drug-lead compound towards the discovery of new anti-cancer agents.

ChemInform Abstract: Racemization‐Free Synthesis of Morpholinone Derivatives from α‐Amino Acids.

AbstractA simple strategy for the preparation of enantiomerically pure N‐tosyl or N‐benzyl protected morpholine, morpholinone, and morpholinecarboxylate derivatives is described.

Novel morpholine scaffolds as selective dopamine (DA) D3 receptor antagonists.

A new series of morpholine derivatives has been identified as selective DA D3 receptor antagonists; their in vitro profile and pharmacokinetic data are provided.

The synthesis and spectral characterization of novel nitrodiene compounds from thiols

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