Synthesis of 3,4-Dihydro-2H-1,3-benzoxazines by Condensation of 2-Hydroxyaldehydes and Primary Amines: Application to the Synthesis of Hydroxy-Substituted and Deuterium-Labeled Compounds

A lysosome-targetable fluorescent probe for the ratiometric detection of formaldehyde in living cells and in vivo

Inspired by the synthetic method of benzoxazine derivatives and our previous research, a fluorescent probe (SWJT-6) was designed for formaldehyde (FA) detection based on the cyclization reaction. The synthetic SWJT-6 showed excellent colorimetric and ratiometric response to formaldehyde, and could be perfectly used as test strips to detect formaldehyde. It also showed a fast detection time (3 min), low detection limit (5.65 μM) and high selectivity for formaldehyde within various interfering analytes. In addition, SWJT-6 has been successfully applied in bioimaging of intracellular and lysosomal formaldehyde in both HeLa cells and zebrafish.

Dual Targeting of MDM4 and FTH1 by MMRi71 for Induced Protein Degradation and p53-Independent Apoptosis in Leukemia Cells

MDM2 and MDM4 are cancer drug targets validated in multiple models for p53-based cancer therapies. The RING domains of MDM2 and non-p53-binder MDM2 splice isoforms form RING domain heterodimer polyubiquitin E3 ligases with MDM4, which regulate p53 stability in vivo and promote tumorigenesis independent of p53. Despite the importance of the MDM2 RING domain in p53 regulation and cancer development, small molecule inhibitors targeting the E3 ligase activity of MDM2-MDM4 are poorly explored. Here, we describe the synthesis and characterization of quinolinol derivatives for the identification of analogs that are capable of targeting the MDM2-MDM4 heterodimer E3 ligase and inducing apoptosis in cells. The structure-activity-relationship (SAR) study identified structural moieties critical for the inhibitory effects toward MDM2-MDM4 E3 ligase, the targeted degradation of MDM4 and FTH1 in cells, and anti-proliferation activity. Lead optimization led to the development of compound MMRi71 with improved activity. In addition to accumulating p53 proteins in wt-p53 bearing cancer cells as expected of any MDM2 inhibitors, MMRi71 effectively kills p53-null leukemia cells, an activity that conventional MDM2-p53 disrupting inhibitors lack. This study provides a prototype structure for developing MDM4/FTH1 dual-targeting inhibitors as potential cancer therapeutics.

Screening of simple carbohydrates as a renewable organocatalyst for the efficient construction of 1,3-benzoxazine scaffold

A convenient protocol for the two component preparation of 1,3-benzoxazines by using several protected and unprotected carbohydrate molecules as organocatalysts have been developed which is broadly applicable to condensation reaction between variety of Mannich bases and paraformaldehyde. This study revealed that fructose have much higher catalytic activity than the other carbohydrates and can be an alternative to metal-containing catalysts as a green renewable organocatalyst for efficient and rapid construction of 1,3-benzoxazine skeleton. In this context, 21 benzoxazine compounds were successfully synthesized and spectral characterizations of these compounds were carried out by spectroscopic methods and elemental analysis. Furthermore, density functional theory (DFT) calculations have been performed to study the detailed mechanism of organocatalyst assisted synthesis of the benzoxazine monomers. The results obtained from these calculations showed that the more realistic reaction pathway involves formation of a phenolate based intermediate which loses a water molecule to form benzenaminium ion. Subsequently, this ion provides the formation of the corresponding benzoxazines with good yields through the intramolecular ring closure step.

Light induced crosslinking of main chain polybenzoxazines

Photo-induced cationic ring opening reactions were performed on main chain polybenzoxazine precursors using iodonium salts.

The first observation on polymerization of 1,3-benzothiazines: synthesis of mono- and bis-thiazine monomers and thermal properties of their polymers

Mono and difunctional 1,3-benzothiazines (PH-a-BZT, PH-ddm-BZT) have been synthesized by a method different from the one reported in the literature.

The inhibition performance of a novel benzenesulfonamide-based benzoxazine compound in the corrosion of X60 carbon steel in an acidizing environment

The inhibition performance of a novel benzenesulfonamide-based benzoxazine compound in the corrosion of X60 carbon steel an acidizing environment has been examined including some highly electronegative atoms.

Synthesis of thioamide containing polybenzoxazines by the Willgerodt–Kindler reaction

Benzoxazines with thioamide linkages were successfully prepared by the Willgerodt–Kindler route.

Nano-Fe3O4@walnut shell/Cu(ii) as a highly effective environmentally friendly catalyst for the one-pot pseudo three-component synthesis of 1,3-oxazine derivatives under solvent-free conditions

Fe₃O₄@walnut shell/Cu(ii) as an eco-friendly bio-based magnetic nano-catalyst was prepared by adding CuCl₂ to Fe₃O₄@walnut shell in alkaline medium. A series of 2-aryl/alkyl-2,3-dihydro-1H-naphtho[1,2-e][1,3]oxazines were synthesized by the one-pot pseudo three-component reaction of β-naphthol, formaldehyde and various amines using nano-Fe₃O₄@walnut shell/Cu(ii) at 60 °C under solvent-free conditions. The catalyst was removed from the reaction mixture by an external magnet and was reusable several times without any considerable loss of its activity. This protocol has several advantages such as excellent yields, short reaction times, clean and convenient procedure, easy work-up and use of an eco-friendly catalyst.

Fe₃O₄@walnut shell/Cu(ii) as an eco-friendly bio-based magnetic nano-catalyst was prepared by adding CuCl₂ to Fe₃O₄@walnut shell in alkaline medium.

Cyanuric chloride as a potent catalyst for the reduction of curing temperature of benzoxazines

Cyanuric chloride (2,4,6-trichloro-1,3,5-triazine, TCT) was used as a catalyst to lower the ring opening polymerization (ROP) temperature of 1,3-benzoxazines.

Synthesis and in vitro evaluation of new translocator protein ligands designed for positron emission tomography

AIM

Dysregulated levels of the translocator protein TSPO 18 KDa have been reported in several disorders, particularly neurodegenerative diseases. This makes TSPO an interesting target for the development of diagnostic biomarkers. Even though several radioligands have already been developed for in vivo TSPO imaging, the ideal TSPO radiotracer has still not been found.

RESULTS

Here, we report the chemical synthesis of a set of new TSPO ligands designed for future application in positron emission tomography, together with the determination of their biological activity and applied ¹¹C-labeling strategy.

CONCLUSION

The lead compound of our series, (R)-[¹¹C]Me@NEBIQUINIDE, showed very promising results and is therefore proposed to be further evaluated under in vivo settings.

Direct Synthesis of Phosphonates and α-Amino-phosphonates from 1,3-Benzoxazines

A straightforward and novel method for transformation of readily available 1,3-benzoxazines to secondary phosphonates and α-aminophosphonates using boron trifluoride etherate as catalyst is developed. The formation of phosphonates proceeds through ortho-quinone methide (o-QM) generated in situ, followed by a phospha-Michael addition reaction. On the other hand, the α-aminophosphonates were obtained by iminium ion formation and the subsequence nucleophilic substitution of alkylphosphites. This method can be also used for the preparation of o-hydroxybenzyl ethers through oxa-Michael addition.

Oxazine Ring-Related Vibrational Modes of Benzoxazine Monomers Using Fully Aromatically Substituted, Deuterated, 15N Isotope Exchanged, and Oxazine-Ring-Substituted Compounds and Theoretical Calculations

Polymerization of benzoxazine resins is indicated by the disappearance of a 960-900 cm^-1 band in infrared spectroscopy (IR). Historically, this band was assigned to the C-H out-of-plane bending of the benzene to which the oxazine ring is attached. This study shows that this band is a mixture of the O-C₂ stretching of the oxazine ring and the phenolic ring vibrational modes. Vibrational frequencies of 3-phenyl-3,4-dihydro-2H-benzo[e][1,3]oxazine (PH-a) and 3-(tert-butyl)-3,4-dihydro-2H-benzo[e][1,3]oxazine (PH-t) are compared with isotope-exchanged and all-substituted compounds. Deuterated benzoxazine monomers, ¹⁵N-isotope exchanged benzoxazine monomers, and all-substituted benzoxazine monomers without aromatic C-H groups are synthesized and studied meticulously. The various isotopic-exchanges involved deuteration around the benzene ring of phenol, selective deuteration of each CH₂ in the O-CH₂-N (2) and N-CH₂-Ar (4) positions on the oxazine ring, or simultaneous deuteration of both positions. The chemical structures were confirmed by ¹H nuclear magnetic resonance spectroscopy (¹H NMR). The IR and Raman spectra of each compound are compared. Further analysis of ¹⁵N isotope-exchanged PH-a indicates the influence of the nitrogen isotope on the band position, both experimentally and theoretically. This finding is important for polymerization studies of benzoxazines that utilize vibrational spectroscopy.

Synthesis, structure and thermolysis of oxazagermines and oxazasilines

Nine new oxazasilines and oxazagermines were characterized and two of them were proven to be suitable precursors for porous Ge@C.

Synthesis and ring-opening polymerization of 2-substituted 1,3-benzoxazine: the first observation of the polymerization of oxazine ring-substituted benzoxazines

2-Substituted 1,3-benzoxazines having a phenyl group as an oxazine ring substituent are synthesized with benzaldehyde through 2-hydroxy-N-phenylbenzylamine structures.

Studies on structurally different diamines and bisphenol benzoxazines

The compounds resorcinolbisbenzoxazine, quinolbisbenzoxazine, p-phenylene diaminebisbenzoxazine, and m-phenylenediaminebisbenzoxazine are prepared. The structural and thermal characterizations of the materials are done using Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H NMR) and 13C NMR, and differential scanning calorimetry. Both FTIR and NMR studies reveal the presence of oxazine rings in the synthesized monomers. The curing exotherm of these bisbenzoxazines is much influenced by the nature of the aromatic unit present in the chosen compound and also on the type of the benzoxazine unit in the system. Curing kinetics is performed using Flynn–Wall–Ozawa, Vyazovkin, and Friedman methods. The apparent activation energies ( Ea-C) for the thermal curing of the synthesized monomers varied and are dependent on the nature and the position of the functional groups present in the compound. The highest Ea-C values are noted for the compounds having the functionalizations being para oriented.

Synthesis and structure-activity relationship studies of 4-((2-hydroxy-3-methoxybenzyl)amino)benzenesulfonamide derivatives as potent and selective inhibitors of 12-lipoxygenase

Human lipoxygenases (LOXs) are a family of iron-containing enzymes which catalyze the oxidation of polyunsaturated fatty acids to provide the corresponding bioactive hydroxyeicosatetraenoic acid (HETE) metabolites. These eicosanoid signaling molecules are involved in a number of physiologic responses such as platelet aggregation, inflammation, and cell proliferation. Our group has taken a particular interest in platelet-type 12-(S)-LOX (12-LOX) because of its demonstrated role in skin diseases, diabetes, platelet hemostasis, thrombosis, and cancer. Herein, we report the identification and medicinal chemistry optimization of a 4-((2-hydroxy-3-methoxybenzyl)amino)benzenesulfonamide-based scaffold. Top compounds, exemplified by 35 and 36, display nM potency against 12-LOX, excellent selectivity over related lipoxygenases and cyclooxygenases, and possess favorable ADME properties. In addition, both compounds inhibit PAR-4 induced aggregation and calcium mobilization in human platelets and reduce 12-HETE in β-cells.

Influence of substituent on equilibrium of benzoxazine synthesis from Mannich base and formaldehyde

Influence of substituents on equilibrium of reaction between Mannich base and formaldehyde to form benzoxazine is the major concern.

Phosphorus-nitrogen compounds. 21. Syntheses, structural investigations, biological activities, and DNA interactions of new N/O spirocyclic phosphazene derivatives. The NMR behaviors of chiral phosphazenes with stereogenic centers upon the addition of chiral solvating agents

The reactions of hexachlorocyclotriphosphazatriene, N(3)P(3)Cl(6), with N/O-donor-type N-alkyl (or aryl)-o-hydroxybenzylamines (1a-1e) produce mono- (2a-2e), di- (3a-3d), and tri- (4a and 4b) spirocyclic phosphazenes. The tetrapyrrolidino monospirocyclic phosphazenes (2f-2i) are prepared from the reactions of partly substituted compounds (2a-2d) with excess pyrrolidine. The dispirodipyrrolidinophosphazenes (3e-3h) and trispirophosphazenes (3i-3k) are obtained from the reactions of trans-dispirophosphazenes with excess pyrrolidine and sodium (3-amino-1-propanoxide), respectively. Compounds 3a-3d have cis and trans geometric isomers. Only the trans isomers of these compounds are isolated. Compounds 3a-3h have two stereogenic P atoms. They are expected to be in cis (meso) and trans (racemic) geometric isomers. In the trans trispiro compounds (3i-3k), there are three stereogenic P atoms. They are expected to be in racemic mixtures. The stereogenic properties of 3a-3k are confirmed by (31)P NMR spectroscopy upon the addition of the chiral solvating agent; (S)-(+)-2,2,2-trifluoro-1-(9'-anthryl)ethanol. The molecular structures of 3i-3k, 4a, and 4b look similar to a propeller, where the chemical environment of one P atom is different from that of others. Additionally, 4a and 4b are also expected to exist as cis-trans-trans and cis-cis-cis geometric isomers, but both of them are found to be in cis-trans-trans geometries. The solid-state structures of 2a, 2e, 2f, 3e, and 3f are determined by X-ray crystallography. The compounds 2f-2i, 3e-3i, and 3k are screened for antibacterial activity against gram-positive and gram-negative bacteria and for antifungal activity against yeast strains. These compounds (except 3f) have shown a strong affinity against most of the bacteria. Minimum inhibitory concentrations (MIC) are determined for 2f-2i, 3e-3i, and 3k. DNA binding and the nature of interaction with pUC18 plasmid DNA are studied. The compounds 2f-2i, 3e-3i, and 3k induce changes on the DNA mobility. The prevention of BamHI and HindIII digestion (except 2g) with compounds indicates that the compounds bind with nucleotides in DNA.