N-alkoxy Derivatives Research Articles

Photocatalytic Activity of n-Alkylamine and n-Alkoxy Derivatives of Layered Perovskite-like Titanates H2Ln2Ti3O10 (Ln = La, Nd) in the Reaction of Hydrogen Production from an Aqueous Solution of Methanol

Two series of hybrid inorganic-organic derivatives, obtained via the modification of protonated Ruddlesden–Popper phases H2Ln2Ti3O10 (Ln = La, Nd) with intercalated n-alkylamines and grafted n-alkoxy groups, have been systematically investigated in relation to photocatalytic hydrogen production from a model of 1 mol % aqueous solution of methanol for the first time. Photocatalytic measurements were performed both for bare samples and for their composites with Pt nanoparticles as a cocatalyst using an advanced scheme, including dark stages, monitoring of the volume concentration of the sample in the reaction suspension during the experiment, shifts of its pH and possible exfoliation of layered compounds into nanolayers. It was found that the incorporation of organic components into the interlayer space of the titanates increases their photocatalytic activity up to 117 times compared with that of the initial compounds. Additional platinization of the hybrid samples’ surface allowed for achieving apparent quantum efficiency of hydrogen evolution of more than 40%. It was established that the photocatalytic activity of the hybrid samples correlates with the hydration degree of their interlayer space, which is considered a separate reaction zone in photocatalysis, and that hydrogen indeed generates from the aqueous methanol solution rather than from organic components of the derivatives.

Synthesis of n-Alkoxy Derivatives of Layered Perovskite-Like Niobate HCa2Nb3O10 and Study of Their Photocatalytic Activity for Hydrogen Production from an Aqueous Solution of Methanol

A series of hybrid inorganic–organic niobates HCa2Nb3O10×ROH, containing n-alkoxy groups of primary alcohols (R = Me, Et, Pr, Bu, Hx, and Dc) grafted in the interlayer space, has been studied for the first time in relation to photocatalytic hydrogen generation from a model 1 mol % aqueous solution of methanol under ultraviolet irradiation. Photocatalytic activity was measured both for bare samples and for their composites with Pt nanoparticles as a cocatalyst. The advanced measurement scheme allowed monitoring the volume concentration of a sample in a suspension during the experiment, its pH, and possible exfoliation of layered compounds into nanolayers. In the series of n-alkoxy derivatives, the maximum rate of hydrogen evolution was achieved over a Pt-loaded ethoxy derivative HCa2Nb3O10×EtOH/Pt. Its apparent quantum efficiency of 20.6% in the 220–350 nm range was found not to be caused by changes in the light absorption region or specific surface area upon ethanol grafting. Moreover, the amounts of hydrogen released during the measurements significantly exceeded those of interlayer organic components, indicating that hydrogen is generated from the reaction solution rather than from the hybrid material.

Indole-3-carbinol and its N-alkoxy derivatives preferentially target ERα-positive breast cancer cells

Indole-3-carbinol (I3C) is a natural anti-carcinogenic compound found at high concentrations in Brassica vegetables. I3C was recently reported to inhibit neutrophil elastase (NE) activity, while consequently limiting the proteolytic processing of full length cyclin E into pro-tumorigenic low molecular weight cyclin E (LMW-E). In this study, we hypothesized that inhibition of NE activity and resultant LMW-E generation is critical to the anti-tumor effects of I3C. LMW-E was predominately expressed by ERα-negative breast cancer cell lines. However, ERα-positive cell lines demonstrated the greatest sensitivity to the anti-tumor effects of I3C and its more potent N-alkoxy derivatives. We found that I3C was incapable of inhibiting NE activity or the generation of LMW-E. Therefore, this pathway did not contribute to the anti-tumor activity of I3C. Gene expression analyzes identified ligand-activated aryl hydrocarbon receptor (AhR), which mediated sensitivity to the anti-tumor effects of I3C in ERα-positive MCF-7 cells. In this model system, the reactive oxygen species (ROS)-induced upregulation of ATF-3 and pro-apoptotic BH3-only proteins (e.g. NOXA) contributed to the sensitivity of ERα-positive breast cancer cells to the anti-tumor effects of I3C. Overexpression of ERα in MDA-MB-231 cells, which normally lack ERα expression, increased sensitivity to the anti-tumor effects of I3C, demonstrating a direct role for ERα in mediating the sensitivity of breast cancer cell lines to I3C. Our results suggest that ERα signaling amplified the pro-apoptotic effect of I3C-induced AhR signaling in luminal breast cancer cell lines, which was mediated in part through oxidative stress induced upregulation of ATF-3 and downstream BH3-only proteins.

Synthesis and spectral characteristics of fluorescent dyes based on coumarin fluorophore and hindered amine stabilizer in solution and polymer matrices

The spectral properties of novel bifunctional dyes based on – coumarin and diethylamino-coumarin and piperidine parent amine and N-oxyl and N-alkoxy derivatives were compared in cyclohexane, methanol, diethylene glycol, acetonitrile and chloroform solvents and in polystyrene, poly(methyl methacrylate) and poly(vinyl chloride) polymer matrices. The fluorescence of the derivatives excited at the longest-wavelength band around 295 nm is very low for coumarin-based dyes, whereas the fluorescence of the 7-diethylamino-3-carboxy coumarin dyes excited at 420 nm is as intense as that of anthracene in comparable conditions. Intramolecular quenching on the singlet level, monitored by fluorescence and expressed as the ratio of Φ NH/Φ NO for the parent amine and N-oxyl and Φ NOR/Φ NO for N-alkyloxy and N-oxyl, is more efficient in polymer matrices than in solvents. The spectral properties of 7-diethylamino-3-carboxy coumarin fluorophores depend on the polarity and viscosity of the environment. Highest values of quantum yield ratio were observed for 7-diethylamino-3-carboxy coumarin dyes in polystyrene and poly(vinylchloride). Though the fluorescence intensity is higher in chloroform or in poly(vinyl chloride) matrices, the intramolecular quenching efficiency of a given fluorophore by nitroxide is higher in low polarity media, such as cyclohexane and polystyrene.

N-Alkoxy derivatization of indole-3-carbinol increases the efficacy of the G1 cell cycle arrest and of I3C-specific regulation of cell cycle gene transcription and activity in human breast cancer cells

Indole-3-carbinol (I3C), a naturally occurring component of Brassica vegetables, such as cabbage, broccoli, and Brussels sprouts, induces a G1 cell cycle arrest of human breast cancer cells. Structure–activity relationships of I3C that mediate this anti-proliferative response were investigated using synthetic and natural I3C derivatives that contain substitutions at the indole nitrogen. Nitrogen substitutions included N-alkoxy substituents of one to four carbons in length, which inhibit dehydration and the formation of the reactive indolenine. Analysis of growth and cell cycle arrest of indole-treated human breast cancer cells revealed a striking increase in efficacy of the N-alkoxy I3C derivatives that is significantly enhanced by the presence of increasing carbon lengths of the N-alkoxy substituents. Compared to I3C, the half maximal growth arrest responses occurred at 23-fold lower indole concentration for N-methoxy I3C, 50-fold lower concentration for N-ethoxy I3C, 217-fold lower concentration for N-propoxy I3C, and 470-fold lower concentration for N-butoxy I3C. At these lower concentrations, each of the N-alkoxy substituted compounds induced the characteristic I3C response in that CDK6 gene expression, CDK6 promoter activity, and CDK2 specific enzymatic activity for its retinoblastoma protein substrate were strongly down regulated. 3-Methoxymethylindole and 3-ethoxymethylindole were approximately as bioactive as I3C, whereas both tryptophol and melatonin failed to induce the cell cycle arrest, showing the importance of the C-3 hydroxy methyl substituent on the indole ring. Taken together, our study establishes the first I3C structure–activity relationship for cytostatic activities, and implicates I3C-based N-alkoxy derivatives as a novel class of potentially more potent experimental therapeutics for breast cancer.

α-Haloalkyl Haloformates and Related Compounds 3.1A Facile Synthesis of Symmetrical and Unsymmetrical UreasviaChloromethyl Carbamates

Abstract Chloromethyl carbamates were prepared by the reaction of chloromethyl chloroformates with amines and found to produce mono-, symmetrically or unsymmetrically di-and trisubstituted ureas including their N-hydroxy and N-alkoxy derivatives in moderate to good yield.

Syntheses of 1,3-disubstituted N-oxy-β-carbolines by the Pictet-Spengler reactions of N-oxy-tryptophan and -tryptamine derivatives

A general and simple approach for the synthesis of N-hydroxy and N-alkoxytryptophan and tryptamine derivatives is presented. Key-intermediates are nitro compounds which are easily accessible from gramine ( 16) and RCH 2N 2. Reduction with Al-amalgam gave in high yields the corresponding hydroxylamines. The N-alkoxy derivatives are accesible by a regioselective O-alkylation of oxime 12 followed by a reduction with borane-trimethylamine complex. The influence of the substituents R 1-R 3 on the reactivity and the relative stereochemistry in the Pictet-Spengler condensation with aldehydes (R 4CHO) has been studied. The increased electrophilic character of the C=N double bond in the intermediate 38 due to the oxygen substituent on the nitrogen increases the reactivity and alters the stereoselectivity.

Behavior of N-alkoxybenzimidzoles with respect to nucleophilic reagents. Attempts to synthesize N-hydroxy-2-aminobenzimidazoles

Various possibilities for the synthesis of N-hydroxy- and N-alkoxy derivatives of 2-aminobenzimidazoles — reductive cyclization of o-nitrophenylureas, the action of sodium amide on 1-alkoxybenzimidazoles, the ammonolysis of 1-alkoxy-2-iodobenzimidazoles, etc. — were investigated. Organometallic compounds of 1-alkoxybenzimidazoles were obtained for the first time, and their reactivities with respect to benzophenone, iodine, and 1-substituted benzimidazoles were studied. 2,2′-Dibenzimidazolyls that contain an alkoxy group in the 1 position were synthesized.

Structure of the Trinuclear Titanium (IV) Alkoxides

THE association of n-alkoxy derivatives of orthotitanic acid was first established as recently as December 1951 by Caughlan et al. 1. Cryoscopic determinations of molecular weight in freezing benzene revealed that Ti(OC2H5)4, Ti(OC3H7)4 and Ti(OC4H9)4 were all trimeric except at very high dilutions when dissociation to the monomer was observed. The association was ascribed to the strong tendency of quadrivalent titanium to attain a six-covalent oxygen environment, as, for example, in rutile or anatase. Caughlan et al. suggested that this could be achieved if each pair of titanium atoms was supported by three bridging alkoxy-groups giving two alternative structures I and II, which were based on the stacking of three TiO6-octahedra face to face. Structure II necessitates a four-co-ordinated square planar oxygen atom attached to three titanium atoms and one alkyl group, and for this reason is considered by us to be untenable.