AsLn2, a luciferin-related modified tripeptide from the bioluminescent earthworm Fridericia heliota

AsLn2, an unusual modified peptide, was isolated from the bioluminescent earthworm Fridericia heliota (Enchytraeidae). Its structure, elucidated by NMR and mass spectrometry, includes residues of tyrosine, CompX (a novel tyrosine modification product, reported in the accompanying paper), and N(omega)-acylated lysine. Chromatography, UV, and ¹H NMR data imply a close structural similarity of AsLn2 with F. heliota luciferin. AsLn2 appears to be an intermediate or by-product in F. heliota luciferin biosynthesis.     

The Synthesis of Hydrophobically Modified Water‐Soluble Polyzwitterionic Copolymers and Responsiveness to Surfactants in Aqueous Solution

Abstract

A novel zwitterionic surfactant monomer containing a carboxybetaine moiety and a 10 carbon aliphatic tail was synthesized and copolymerized with acrylamide to yield a water‐soluble, hydrophobically modified zwitterionic polymer [Poly(acrylamide‐co‐(3‐(N,N‐dimethyl‐N‐3′‐(N′‐acryloyl)aza‐tridecyl) ammonio butanoate))]. The response of aqueous polymer solutions to the addition of various classes of surfactant was investigated and compared to that of an analogous novel polymer containing the sulfobetaine zwitterion [Poly(acrylamide‐co‐(N,N‐dimethyl‐N‐3′‐(N′‐acryloyl) aza‐tridecyl) ammonio propane sulfonate))]. It was found that the addition of sodium dodecyl sulfate (SDS) produced a pronounced maximum in viscosity, while dodecyltrimethylammoniumbromide (DTAB), N‐dodecyl‐N,N‐dimethylammonio‐1‐propanesulfonate (SB3‐12), and Triton X‐100 either had no effect, or produced a decrease in viscosity. The effect of pH on polymer–SDS interaction was also studied. Lowering pH increased the SDS–polymer interaction and significantly shifted viscosity enhancement to a higher SDS concentration.     

N?O Bond as a Glycosidic‐Bond Surrogate: Synthetic Studies Toward Polyhydroxylated N‐Alkoxypiperidines

A series of novel polyhydroxylated N‐alkoxypiperidines has been synthesized by ring‐closing double reductive amination (DRA) of highly functionalized 1,5‐dialdehydes with various hydroxylamines. The required saccharide‐based dialdehydes were prepared efficiently from sodium cyclopentadienylide in seven steps. A two‐step protocol has been developed for the DRA; it led, after deprotection, to isofagomine, 3‐deoxyisofagomine, and numerous other N‐alkoxy analogues. The barrier to inversion in these polyhydroxylated N‐alkoxypiperidine derivatives was found by variable‐temperature NMR methods to be approximately 15 kcal mol^?1. With the exception of N‐hydroxyisofagomine itself, none of the compounds prepared showed significant inhibitory activity against sweet almond β‐glucosidase.     

An Efficient Synthesis of Novel 2‐(5‐indolyl)‐1H‐benzimidazole Derivatives and Evaluation of Their Antimicrobial Activities

In this paper, we report the synthesis of novel 2‐(5‐indolyl)‐1H‐benzimidazole derivatives. The methodology involves the Sonogashira reaction of 4‐(1H‐benzimidazol‐2‐yl)‐2‐bromo‐N,N‐dimethylaniline ( 3 ) with variety of terminal alkynes to get corresponding novel 4‐(1H‐benzimidazol‐2‐yl)‐2‐alkynyl‐N,N‐dimethylaniline derivatives ( 4 ). These compounds on iodocyclization afforded novel iodoindolylbenzimidazole derivatives ( 5 ). The resulting compounds were functionalized further via palladium‐mediated carbon–carbon bond formation for generating novel structurally diversified heterocyclic compounds. All these newly synthesized compounds were evaluated for antimicrobial activity.     

pH‐responsive ionic poly(N,N‐diethylaminoethyl methacrylate‐co‐N‐vinyl‐2‐pyrrolidone) hydrogels: Synthesis and swelling properties

A series of an ionic hydrogels composed of N,N‐diethylaminoethyl methacrylamide (DEAEMA), N‐vinyl‐2‐pyrrolidone (VP), and itaconic acid were synthesized by free‐radical cross‐linking copolymerization in water–ethanol mixture by using N,N‐methylenebis(acrylamide) as the cross‐linker, ammonium persulfate as the initiator, and N,N,N′,N′‐tetramethylenediamine as the activator. The swelling behaviors of these hydrogels were analyzed in buffer solutions at various pH. It was observed that the swelling behavior of cross‐linked ionic poly(N,N‐diethylaminoethyl methacrylamide‐co‐N‐vinyl‐2‐pyrrolidone) [P(DEAEMA/VP)] hydrogels at different pH agreed with the modified Flory–Rehner equation based on the affine network model and the ideal Donnan theory. The swelling process in buffer solutions at various pH was found to be Fickian‐type diffusion. The pH‐reversibility and on–off switching properties of the P(DEAEMA/VP) hydrogels may be considered as good candidate to design novel drug‐delivery system. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2819–2828, 2005     

Formation of cyclic acylphosphoramidates in mass spectra of N‐monoalkyloxyphosphoryl amino acids using electrospray ionization tandem mass spectrometry

The fragmentation reactions of N‐monoalkyloxyphosphoryl amino acids (N‐MAP‐AAs) were studied by electrospray ionization tandem mass spectrometry (ESI‐MS). The sodiated cyclic acylphosphoramidates (CAPAs) were formed through a characteristic pentacoordinate phosphate participated rearrangement reaction in the positive‐ion ESI‐MS/MS and HR‐MS/MS of N‐MAP‐AAs, in which the fragmentation patterns were clearly different from those observed in the corresponding ESI‐MS/MS of N‐dialkyloxyphosphoryl amino acids/peptides and N‐phosphono amino acids. The formation of CAPAs depended on the chemical structures of N‐terminal phosphoryl groups, such as alkyloxy group, negative charge and alkali metal ion. A possible integrated rearrangement mechanism for both P‐N to P‐O phosphoryl group migration and formation of CAPAs was proposed. The fragmentation patterns of CAPAs as novel intermediates in gas phase were also investigated. In addition, it was found that the formation of α‐amino acid CAPAs was more favorable than β‐ or γ‐CAPAs in gas phase, which was consistent with previous solution‐phase experiments. Copyright © 2010 John Wiley & Sons, Ltd.     

Novel isoxazoline ligand with ferrocene backbone: preparation and application in Heck reaction with water as solvent

Two novel isoxazoline N,N‐bidentate ligands with ferrocene backbone have been synthesized and employed for the palladium‐catalyzed Heck coupling reaction. Among them, 1,3‐bis‐(5‐ferrocenylisoxazoline‐3‐yl)benzene was found to be thermally stable and a highly effective ligand for Heck coupling reaction in neat water without N₂ protection, affording the desired coupling products in good to excellent yield with high diastereoselectivity. The developed catalytic system was also well workable for 1,2‐disubstituted alkenes, which were less involved in the Heck reaction for its larger steric hindrance. Copyright © 2014 John Wiley & Sons, Ltd.     

Preparation and applications of novel amphiphilic fluoroalkyl end‐capped oligomers‐clay nanocomposites

Nonionic‐type amphiphilic fluoroalkyl end‐capped acryloylmorpholine and N,N‐dimethylacrylamide homooligomers were found to be new convenient intercalating agents for the achievement of an enlarged basal spacing of the clay layers to afford fluorinated oligomers‐clay nanocomposites. These novel fluoroalkyl end‐capped oligomers‐clay nanocomposites were found to exhibit good dispersibility and stability in aqueous and organic media, and were applied to the surface modification of traditional organic polymeric materials such as poly(methyl methacrylate). Copyright © 2006 John Wiley & Sons, Ltd.     

Synthesis and biological activity of novel N‐tert‐butyl‐N,N′‐substitutedbenzoylhydrazines containing 2‐methyl‐3‐(triphenylgermanyl)propoxycarbonyl

In a search for new insect growth regulators with unusual biological properties and different activity spectrum, we thought that the preservation of the bioactive unit and the introduction of 2‐methyl‐3‐(triphenylgermanyl)propoxycarbonyl in N‐tert‐butyl‐N,N′‐dibenzoylhydrazine would enhance their larvicidal activities to a significant degree. Therefore, we designed and synthesized N′‐tert‐butyl‐N′‐[2‐methyl‐3‐(triphenylgermanyl)propoxycarbonyl]‐N‐benzoylhydrazine and analogs by two procedures. These novel compounds were characterized by elemental analyses, IR, and ¹H NMR. At the same time, N‐tert‐butyl‐N‐substitutedbenzoylhydrazines were prepared by a new method, and some reactions involved were studied. The preliminary results indicate that some compounds have inhibitory effects against plant pathogenetic bacteria such as early blight of tomato. Copyright © 2002 John Wiley & Sons, Ltd.     

Synthesis and Mesogenic Properties of Novel Terthiophene Derivatives

To develop novel oligothiophene‐based liquid crystals involving hydrogen bonding, new terthiophene derivatives containing a stearylamide group, N,N′‐distearyl‐5,5″‐dicyano‐2,2′∶5′,2″‐terthiophene‐4,4″‐dicarboxamide (DNC₁₈DCN 3T) and N,N′‐distearyl‐5,5′‐dipropyl‐2,2′∶5′,2′‐terthiophene‐4,4″‐dicarboxamide (DNC₁₈ DP3T), were designed and synthesized, and their thermal behavior examined. Although DNC₁₈DP3T did not exhibit liquid crystallinity, DNC₁₈DCN3T was found to form smectic A phase.     

Separation and identification of purine nucleosides in the urine of patients with malignant cancer by reverse phase liquid chromatography/electrospray tandem mass spectrometry

Urinary‐modified nucleosides have a potential role as cancer biomarkers for a number of malignant diseases. High performance liquid chromatography (HPLC) was combined with full‐scan mass spectrometry, MS/MS analysis and accurate mass measurements in order to identify purine nucleosides purified from urine. Potential purine nucleosides were assessed by their evident UV absorbance in the HPLC chromatogram and then further examined by the mass spectrometric techniques. In this manner, numerous modified purine nucleosides were identified in the urine samples from cancer patients including xanthine, adenosine, N1‐methyladenosine, 5′‐deoxy‐5′‐methylthioadenosine, 2‐methyladenosine, N6‐threonylcarbamoyladenosine, inosine, N1‐methylinosine, guanosine, N1‐methylguanosine, N7‐methylguanine, N2‐methylguanosine, N2,N2‐dimethyguanosine, N2,N2,N7‐trimethylguanosine. Furthermore, a number of novel purine nucleosides were tentatively identified via critical interpretation of the combined mass spectrometric data including N3‐methyladenosine, N7‐methyladenine, 5′‐dehydro‐2′‐deoxyinosine, N3‐methylguanine, O6‐methylguanosine, N1,N2,N7‐trimethylguanosine, N1‐methyl‐N2‐ethylguanosine and N7‐methyl‐N1‐ethylguanosine. Copyright © 2009 John Wiley & Sons, Ltd.     

Design,Synthesis, Structure‐Activity Relationship and Insecticidal Activities of Trifluoromethyl‐Containing Sulfiliminyl and Sulfoximinyl Phthalic Acid Diamide Structure

Due to a novel mode action, low toxicity to mammals and low residue characteristics, phthalic acid diamides have aroused considerable interests in agricultural chemistry. With introduction of N‐cyano, N‐trifluoroacetyl, N‐carbamoylsulfiliminyl and sulfoximinyl substituents into phthalamides, 12 novel derivatives containing trifluoromethyl moiety were designed and synthesized. All title compounds were characterized by ¹H NMR and high‐resolution mass spectrometry. The preliminary results of biological activity assessment indicated that some title compounds exhibited moderate to good insecticidal activities against oriental armyworm (Pseudaletia separata Walker). In particular, Va gave higher activity against oriental armyworm and diamondback moth. The present work reported that the new trifluoromethylated diamides incorporating N‐trifluoroacetylsulfoximinyl moieties are potential lead compounds for further structure optimization, providing some insight into the relating structure‐activity relationship.     

Synthesis of Amphoteric Surfactants via Esterification Process

This article describes the synthesis of a novel amphoteric surfactant through esterification of 2‐hydroxy‐N,N,N‐trimethylethanaminium chloride with maleic acid alkyl ester of C₈, C₁₀, and C₁₂ chain length in the presence of base. Maleic acid alkyl esters were synthesized by the reaction of maleic anhydride with alkyl alcohol. Surface‐active properties were studied by different techniques such as surface tension and foaming property. Critical micelle concentrations (CMCs) were found by using surface tension values to learn the effect of chain length on CMC of synthesized surfactants. The best result obtained has minimal coproducts, an environmentally safer route, and a very good CMC value of surfactants.     

Dicationic ionic liquids as recyclable catalysts for one‐pot solvent‐free synthesis of α‐aminophosphonates

Some task‐specific ionic liquids N,N,N′,N′‐tetramethyl‐N,N′‐dipropanesulfonic acid ethylene‐diammonium hydrogen sulfate, N,N,N′,N′‐tetramethyl‐N,N′‐dipropanesulfonic acid‐1,3‐propanediammonium hydrogen sulfate, N,N,N′,N′‐ tetramethyl‐N,N′‐ dipropanesulfonic acid‐1,6‐hexanediammonium hydrogen sulfate were prepared. These ionic liquids could be used as efficient and recyclable catalysts for the synthesis of α‐aminophosphonates at room temperature via an one‐pot three‐component reaction under organic solvent‐free conditions with good yields of 83–96%. The postprocessing was simple, and the catalysts could be reused at least six times without noticeably decreasing the catalytic activity. The novel clean procedure offers the advantages including short reaction time, good yields, operational simplicity, and environmentally benign. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 22:1–5, 2011; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20647     

Heterocyclization of Imidates with 3‐Alkyl‐5‐amino‐1‐phenyl‐1,2,4‐triazoles: Synthesis of New Triazolotriazines

Some novel triazolo[4,3‐a]triazines derivatives were synthesized by reaction of N‐cyanoimidates and N‐ethoxycarbonylimidates with 3‐alkyl‐5‐amino‐1‐phenyl‐1,2,4‐triazoles.     

Green synthesis of Cu/zirconium silicate nanocomposite by using Rubia tinctorum leaf extract and its application in the preparation of N‐benzyl‐N‐arylcyanamides

A simple and convenient protocol was established for the synthesis of the N‐benzyl‐N‐arylcyanamides through N‐benzylation of a wide variety of arylcyanamides using copper nanoparticles immobilized on natural zirconium silicate as a novel and green heterogeneous catalyst. In this study, we showed a novel, cost efficient, convenient and simple method for green synthesis of Cu/zirconium silicate nanocomposite by using Rubia tinctorum leaf extract as capping and reducing agent. The structure of the novel catalyst was successfully characterized using a number of micro/spectroscopic techniques such as XRD, FESEM, BET, EDS, TEM, FT‐IR and elemental mapping. TEM micrographs of obtaining biocatalyst revealed mostly spherical particles with an average diameter of about 15–25 nm on the surface of natural support. The prepared catalyst was used in the N‐benzylation of a variety of arylcyanamides with benzyl bromide and showed high activity and stability for the efficient synthesis of N‐benzylarylcyanamides in good yields. Remarkably, the catalyst can be easily recovered from the reaction medium and reused up to five runs without losing its catalytic activity.     

Characteristic ion clusters as determinants for the identification of pyrrolizidine alkaloid N‐oxides in pyrrolizidine alkaloid–containing natural products using HPLC–MS analysis

Pyrrolizidine alkaloid (PA)–containing plants are widely distributed in the world. PAs are hepatotoxic, affecting livestock and humans. PA N‐oxides are often present together with PAs in plants and also exhibit hepatotoxicity but with less potency. HPLC–MS is generally used to analyze PA‐containing herbs, although PA references are unavailable in most cases. However, to date, without reference standards, HPLC–MS methodology cannot distinguish PA N‐oxides from PAs because they both produce the same characteristic ions in mass spectra. In the present study, the mass spectra of 10 PA N‐oxides and the corresponding PAs were systemically investigated using HPLC–MS to define the characteristic mass fragment ions specific to PAs and PA N‐oxides. Mass spectra of toxic retronecine‐type PA N‐oxides exhibited two characteristic ion clusters at m/z 118–120 and 136–138. These ion clusters were produced by three unique fragmentation pathways of PA N‐oxides and were not found in their corresponding PAs. Similarly, the nontoxic platynecine‐type PA N‐oxides also fragmented via three similar pathways to form two characteristic ion clusters at m/z 120–122 and 138–140. Further application of using these characteristic ion clusters allowed successful and rapid identification of PAs and PA N‐oxides in two PA‐containing herbal plants. Our results demonstrated, for the first time, that these characteristic ion clusters are unique determinants to discriminate PA N‐oxides from PAs even without the availability of reference samples. Our findings provide a novel and specific method to differentiate PA N‐oxides from PAs in PA‐containing natural products, which is crucial for the assessment of their intoxication. Copyright © 2012 John Wiley & Sons, Ltd.     

Methyl Iodide Accelerated Asymmetric Epoxidation of Alkenes Catalyzed by Chiral Salen-Mn（Ⅲ） Complexes with Tertiary Amine Units

A series of chiral salen-Mn（Ⅲ） complexes featuring two tertiary amine units were synthesized and employed in the enantioselective epoxidation of unfunctionalized alkenes in the presence of pyridine N-oxide and 2,6-dimethylpyridine N-oxide as proximal ligands, respectively. Moderate to high enantioselectivity and acceptable yields were achieved when NaClO was used as terminal oxidant under CH2Cl2/H2O biphasic media. Methyl iodide was found to be an effective additive to accelerate the epoxidation, possibly owing to the formation of quaternary ammonium units on catalysts, which may facilitate the reaction in an oil/water biphasic medium. The subsequent stimulation experiment was carried out, and the resulting ESI-HRMS analysis revealed the formation of a novel （salen）manganese（m） intermediate featuring two quaternary ammonium units, and bearing a pyridine N-oxide and a molecule of water simultaneously axially-coordinated backbone.     

Synthesis of novel poly(aryl ether amide)s containing the phthalazinone moiety

Two novel heterocyclic diamine monomers: 1,2-dihydro-2-(4-aminophenyl)-4-[ 4-( 4-aminophenoxy) phenyl ]-(2H )-phtha-lazin-1-one and 1, 2-dihydro-2-( 4-aminophenyl )-4-[ 4-( 4-aminophenoxy) -3, 5-dimethylphenyl ] - (2H) -phthalazin-1-one were successfully synthesized using readily available heterocyclic bisphenol-like monomers through two steps in high yield. A series of novel poly( aryl ether amide)s containing the phthalazinone moiety with inherent viscosities of 1.16-1.67 dL/g were prepared by the direct polymerization of the novel diamines and aromatic dicarboxylic acids using triphenyl phosphite and pyridine as condensing agents. The polymers were readily soluble in a variety of solvents such as N, N-dimethyl-formamide (DMF), N,N-dimethylacetamide (DMAc), dimethylsulfoxide ( DMSO ), N-methyl-2-pyrrolidinone (NMP), and pyridine. The polymers had high glass transition temperatures (Tg) in the 291-329℃ range.