Synthesis of (E)‐ and (Z)‐5‐(Bromomethylene)furan‐2(5H)‐one by Bromodecarboxylation of (E)‐2‐(5‐Oxofuran‐2(5H)‐ylidene)acetic Acid

(E)‐ and (Z)‐5‐(bromomethylene)furan‐2(5H)‐one have been prepared starting from the commercially available adduct between furan and maleic anhydride. A bromodecarboxylation reaction is a key step in the synthesis. The reaction gives the (E)‐ or (Z)‐5‐(bromomethylene)furan‐2(5H)‐one as the major product, dependent on the method used in the bromodecarboxylation.     

Amino Acids as a Chiral Pool: Synthesis of (S)‐and (R)‐2‐N‐Carbomethoxy‐5‐aminoindane from (S)‐ and (R)‐Phenylalanines

Enantioselective syntheses of (R)‐and (S)‐2‐N‐carbomethoxy‐5‐aminoindanes from (R)‐ and (S)‐phenylalanines, respectively, are described. A Friedel–Crafts reaction employing N‐carbomethoxy phenylalanine leads to chiral 2‐N‐carbomethoxy‐1‐indanone, which is diastereoselectively reduced to 1‐hydroxy‐2‐N‐carbomethoxyindane. After protection of the hydroxyl group, a regioselective nitration gives a 6‐nitroindane intermediate, which upon hydrogenation affords (R)‐or (S)‐2‐N‐carbomethoxy‐5‐aminoindane.     

Efficient Synthesis of 2‐(N‐Substituted)‐2‐imidazolines and 2‐(N‐Substituted)‐1,4,5,6‐tetrahydropyrimidines

A general method for the preparation of 2‐(N‐Substituted)‐2‐imidazolines and 2‐(N‐Substituted)‐1,4,5,6‐tetrahydropyrimidines is described. These heterocycles can be synthesized from their respective anilines with 2‐chloro‐2‐imidazoline or 2‐chloro‐1,4,5,6‐tetrahydropyrimidine, generated in situ from imidazolidin‐2‐one and tetrahydropyrimidin‐2(1H)‐one activated by dimethyl chlorophosphate, in good to excellent yields.     

Synthesis and Crystallographic Study of1,6‐bis‐(N‐phenothiazinyl)‐2,4‐hexadiyne

1,6‐bis‐(N‐phenothiazinyl)‐2,4‐hexadiyne (I) was synthesized in high yield by oxidative coupling of N‐propargyl phenothiazine. Grown from methylene chloride‐hexane solution, I is a monoclinic crystal, space group C2/c a=14.9500(18) Å; b=13.5512(15) Å; c=12.0116(10) Å; β=102.628(9)° Å; V=2374.6(4) ų. The intermolecular distances and arrangement of I in the unit cell preclude the usual diacetylene reactivity. Nevertheless, heating of I at 145°C results in decomposition of I to phenothiazine and a dark brown solid. In addition, cation‐radicals of I were prepared by oxidation with nitrosonium tetrafluoroborate and iodine to give stable ion‐radical salts.     

Synthesis,Characterization and Photocrosslinking Properties of Poly(1‐(4‐Methacrylamidophenyl)‐1‐(4‐nitrophenyl)prop‐1‐en‐3‐one)

The phenylmethacrylamide monomer, 1‐(4‐methacrylamidophenyl)‐1‐(4‐nitrophenyl)prop‐1‐en‐3‐one (MPNP) containing a photosensitive group was synthesized by reacting 4‐nitrocinnamoylaniline with methacryloyl chloride in the presence of triethylamine at 0–5°C. The functional monomer, MPNP was polymerized in ethyl methyl ketone (EMK) under nitrogen atmosphere at 70°C using benzoyl peroxide (BPO) as the initiator. The synthesized polymer was characterized by UV, IR, ¹H‐NMR and ¹³C‐NMR spectroscopy. The molecular weight data of the polymer as obtained from gel permeation chromatography suggests a higher tendency for chain termination by radical recombination than disproportionation. The thermal studies of the polymer were obtained from thermogravimetric analysis. The glass transition temperature of the polymer was determined by differential scanning calorimetry. The solubility of the polymer was tested in various organic solvents at room temperature. The photosensitivity of the polymer was investigated in various solvents in the presence and absence of triplet photosensitizers. The effect of the different solvents nature and concentration on the rate of photocrosslinking of the polymer were also examined for using the polymer as negative photoresist materials.     

Simple and Convenient Synthesis of 4‐Unsubstituted‐3‐(3‐Oxoalkyl)isocoumarins

A simple transformation of 2‐alkylfurans and 2‐formylbenzoic acids into 4‐unsubstituted 3‐(3‐oxoalkyl)isocoumarins is described. It is based on the synthesis of 2‐(2‐carboxybenzyl)furans followed by their acid‐catalyzed recyclization to the target isocoumarins.     

Synthesis and Characterization of Alkyl and Aryl‐(4‐methyl‐6‐nitro‐quinolin‐2‐yl)amines: X‐Ray Structures of Ethyl and Cyclohexyl‐(4‐methyl‐6‐nitro‐quinolin‐2‐yl)amine

Abstract

We have synthesized and characterized a series of alkyl and aryl‐(4‐methyl‐6‐nitro‐quinolin‐2‐yl)amines through a high‐yield, three‐step procedure starting from 4‐methylquinolin‐2‐ol. Nitration using concentrated nitric/sulfuric acids, followed by chlorination in phosphorus oxychloride, yielded 2‐chloro‐4‐methyl‐6‐nitro‐quinoline. All of the intermediates and aminated products have been characterized by multinuclear (¹H and ¹³C) NMR spectroscopy, elemental analysis, and, in the case of the two title compounds (ethyl and cyclohexyl‐(4‐methyl‐6‐nitro‐quinolin‐2‐yl)amine), a single crystal X‐ray structure was obtained to verify the nature of the new materials.     

Synthesis and Properties of Poly(AAm‐KMA‐MA) Hydrogels

In this investigation, poly(acrylamide‐co‐potassium methacrylate‐co‐maleic acid) hydrogels, poly(AAm‐KMA‐MA) were synthesized by redox copolymerization in aqueous solution. The effect of reaction parameters, such as concentration of maleic acid, crosslinking agent, initiator and activator, on the swelling behavior was investigated in detail. The swelling/diffusion characteristics were also evaluated for 1,4‐butanediol diacrylate (BDDA) and 1,2‐ethyleneglycol dimethacrylate (EGDMA) crosslinked hydrogels having different amounts of maleic acid. The results indicate that the water diffusion of hydrogels was of a non‐Fickian type. The hydrogels were characterized by IR spectroscopy and thermogravimetric analysis (TGA). Their surface characteristics were observed by using scanning electron microscopy (SEM). Furthermore, their swelling phenomena in different pH and salt solutions and simulated biological fluids was also studied.     

Efficient Synthesis of Biologically Active (±)‐Confluentin and (±)‐Daurichromenic Acid

One‐step synthesis of biologically active (±)‐confluentin is described from commercially available orcinol with trans,trans‐farnesal in the presence of ethylenediamine diacetate as a catalyst. Further conversion of synthetic confluentin to highly potent anti‐HIV agent, (±)‐daurichromenic acid, is accomplished by formylation and oxidation in two steps.     

Synthesis and study of 4‐(4′‐n‐alkoxybenzoyloxybenzoyl)‐4′′‐n‐butoxyanilides

Thirteen compounds with ester and amide linkages were synthesized and their mesogenic properties evaluated. Methyl to n‐propyl derivatives exhibit nematic phases, n‐butyl to n‐decyl derivatives exhibit smectic and nematic mesophases, whereas n‐dodecyl to n‐octadecyl derivatives exhibit only smectic phases. All the smectic homologues exhibit smectic C phases. Middle members of the homologous series exhibit polymorphism of smectic mesophase. A plot of transition temperatures versus number of carbon atoms in the alkoxy chain reveals an odd–even effect for nematic–isotropic transition temperatures. Nematic–isotropic and smectic–cholesteric thermal stabilities of the prepared compounds (series I) are higher compared to those of previously reported compounds, series A, B and C. The results indicate that a simple reversal of a central linkage has a dramatic effect on the appearance of smectic mesophase in a homologous series. The structures of the synthesized compounds were characterized using elemental analysis, thin‐layer chromatography and spectral data.     

Preparation and Characterization of Poly(N‐Vinylpyrrolidone‐co‐Methacrylic Acid) Hydrogels

In this study, N‐vinylpyrrolidone (VP)/methacrylic acid (MAA) copolymers have been prepared at three different mole percents, the methacrylic acid composition being around 5, 10, 15%. MAA and VP monomer mixtures have been irradiated in ⁶⁰Co‐γ source at different irradiation doses and percent conversions have been determined gravimetrically. ～80% conversion of monomers into hydrogels were performed at 3.4 kGy irradiation dose. These hydrogels were swollen in distilled water at pH 4.0, 7.0, and 9.0. P(VP/MAA) hydrogel which contains 5% methacrylic acid showed the maximum % swelling at pH 9.0 in water. Diffusion of water was found to be of non‐Fickian character. Diffusion coefficients of water in P(VP/MAA) hydrogels were calculated. Initial swelling rates of P(VP/MAA) hydrogels increased with increasing pH and MAA content in hydrogels. Swelling kinetics of P(VP/MAA) hydrogels was found to be of second order. Thermal behavior of PMAA, PVP and P(VP/MAA) hydrogel were investigated by thermal analysis. P(VP/MAA) hydrogel gained new thermal properties and the temperature for maximum weight loss and temperature for half‐life of P(VP/MAA) hydrogel were determined.     

Synthesis and Characterization of Hydroxyl‐Terminated Poly(γ‐benzyl‐L‐glutamate)

In order to provide an active end group of hydroxyl group and improve the hydrophility of poly(γ‐benzyl‐L‐glutamate) (PBLG), ethanolamine (EA) was utilized as the initiator to initiate N‐carboxy‐γ‐benzyl‐L‐glutamate anhydride (Bz‐L‐Glu‐NCA) polymerization. The prepared hydroxyl‐terminated PBLG (HO‐PBLG) was fully characterized by FTIR, ¹H‐NMR, XPS, XRD, DSC, and GPC. The results of FTIR and XRD indicated that the chain conformation of HO‐PBLG predominantly presented α‐helix. The water contact angle was measured to confirm that the hydrophilicity was improved by the introduction of hydroxyl group. Chondrocytes studies showed that the cells attachment efficiency on the HO‐PBLG film was good and the cells grew well.     

Synthesis of (R)‐Japonilure and (4R,9Z)‐9‐Octadecen‐4‐olide,Pheromones of the Japanese Beetle and Currant Stem Girdler

Asymmetric total synthesis of the sex pheromones of Japanese beetle and currant stem girdler, (R)‐japonilure (1) and (4R,9Z)‐9‐octadecen‐4‐olide (2), has been achieved.     

Synthesis of (±)‐ar‐Macrocarpene

An efficient first synthesis of the sesquiterpene ar‐macrocarpene, an irregular sesquiterpene isolated from Cupressus macrocarpa foliage, starting from 3‐methylcyclohexenone has been described, which confirmed the structures of macrocarpenes.     

Synthesis of Some Unusual (1,2,4‐Oxadiazole)‐Linked Hexenopyranosides and Mannopyranosides

A copper‐catalyzed reaction of propargyl 4,6‐di‐O‐acetyl‐2,3‐dideoxy‐α‐D‐erythro‐hex‐2‐enopyranoside with 3‐(4‐azidophenyl)‐1,2,4‐oxadiazoles gave the corresponding hexenopyranosides bearing an 1,2,4‐oxadiazole subunit in the aglyconic part of the molecule. The same reaction between ethyl 4‐azido‐2,3,4‐trideoxy‐α‐D‐erythro‐hex‐2‐enopyranoside and acetylenic 1,2,4‐oxadiazoles afforded the corresponding hexenopyranosides carrying a triazole and a 1,2,4‐oxadiazole ring at C‐4 of the carbohydrate. Combination of the two sequences gave hexenopyranosides displaying two 1,2,4‐oxadiazole subunits, each one being embedded in the C‐1 and C‐4 frameworks, of the carbohydrate moiety. A simple dihydroxylation reaction of these unsaturated carbohydrates yielded a series of mannopyranosides bearing one or two 1,2,4‐oxadiazole subunits at C‐1 or C‐4. These new compounds were evaluated for their cytotoxic activities against two cell strains: NCI‐H₂₉₂ (lung carcinoma) and Hep‐2 (larynx carcinoma), some of them presenting impressive cell growth inhibitions.     

Nonextractive Trace Level Simultaneous Determination of Mercury(II) and Zinc(II) in Environmental Samples with 2‐(5‐Bromo‐2‐pyridylazo)‐5‐diethylaminophenol and Cetylpyridinium Chloride

Abstract

A simple, rapid, selective, and sensitive method for the derivative spectrophotometric determination of Hg(II) and its simultaneous determination in the presence of Zn(II) using 2‐(5‐bromo‐2‐pyridylazo)‐5‐diethylaminophenol in the presence of cetylpyridinium chloride, a cationic surfactant, has been developed. The molar absorption coefficient and analytical sensitivity of the 1∶1 Hg(II) complex at 558 nm (λ_max) are 5.78×10⁴ L mol^?1 cm^?1 and 0.67 ng mL^?1, respectively. The detection limit of Hg(II) is 1.40×10^?2 ng mL^?1, and Beer's law is valid in the concentration range 0.05–2.40 µg mL^?1. Overlapping spectral profiles of Hg(II) and Zn(II) complexes in zero‐order mode interfere in their simultaneous determination. However, 0.10–2.00 µg mL^?1 of Hg(II) and 0.065–0.650 µg mL^?1 of Zn(II), when present together, can be simultaneously determined at zero cross point of the derivative spectrum, without any prior separation. The relative standard deviation for six replicate measurements of solutions containing 0.134 µg mL^?1 of Hg(II) and 0.620 µg mL^?1 of Zn(II) is 1.72 and 1.47%, respectively. The proposed method has successfully been evaluated for trace level simultaneous determination of Hg(II) and Zn(II) in environmental samples.     

Synthesis and Characterization of Hexadecaaniline‐Grafted Comb‐like Poly(maleic acid‐alt‐1‐octadecene)

Highly soluble hexadecaaniline (A₁₆)‐grafted polyolefin derivatives poly(maleic acid‐hexadecaanilinamide‐alt‐1‐octadecene) (PMAO‐A₁₆) in a comb‐like configuration with alternate linear hexadecane and A₁₆ side‐chains were synthesized and characterized. The structure of PMAO‐A₁₆ was substantiated by infrared and UV‐Vis spectra showing high intensity of characteristic absorption peaks corresponding to a high degree of A₁₆ attachments. Covalent grafting of hexadecaanilines onto the polymer backbone of PMAO was confirmed by the detection of a new amide [–(C[dbnd]O)–NH–] absorption band appearing at 1661 cm^?1 accompanied with the full disappearance of anhydride carbonyl absorptions. Based on the comparison between TGA profiles of PMAO‐A₁₆ and hexadecaaniline, a 12.5% wt loss at 365–600°C was accounted for full elimination of aliphatic side‐chains that matches approximately with the weight percentage of total hexadecane arms (12.7%). The data revealed a nearly quantitative yield of A₁₆ grafting on anhydride subunits leading to complete conversion of PMAO into PMAO‐A₁₆. Furthermore, preliminary ¹H‐NMR study of PMAO‐A₁₆ indicated its capability to undergo molecular self‐assembly in DMSO where A₁₆s were dispersed in the solvent phase with hexadecane side‐chains located in a phase‐separated domain.     

Synthesis and Antimicrobial Activity of 4‐Aryl‐5‐phenyl‐imino‐3‐(tetra‐O‐benzoyl‐β‐D‐glucopyranosylimino)‐1,2,4‐dithiazolidines (Hydrochlorides)

Abstract

Synthesis of 4‐aryl‐5‐phenylimino‐3‐(tetra‐O‐benzoyl‐β‐D‐glucopyranosylimino)‐1,2,4‐dithiazolidines (hydrochlorides) is described. These compounds were screened for their antibacterial and antifungal activity against Escherichia coli, Staphylococcus aureus, P. vulgaris, Pseudomonas, Bacillus, Salomonella sp., Aspergilus niger, and Fusarium. The identities of these new N‐glucosides have been established on the basis of usual chemical transformation IR, NMR, and mass spectral studies.     

Facile Synthesis of (S,S)‐1,2‐Diacylamides and (S,S)‐1,2‐Diamines with C 2‐Symmetry

A series of chiral vicinal tertiary diacylamides with C ₂‐symmetry was synthesized from (S)‐α‐phenylethylamine, different aromatic aldehydes, and oxalyl chloride. The diacylamides obtained were then reduced to afford chiral vicinal diamines with C ₂‐symmetry. We propose that the diacylamides existed in four stable conformational isomers in solution because of the dihedral angle between acylamide bonds.     

Synthesis and Characterization of Chitosan‐graft‐Poly(3‐(trimethoxysilyl)propyl methacrylate) Initiated by Ceric (IV) Ion

The grafting of 3‐(trimethoxysilyl)propyl methacrylate (TMSPM) onto chitosan by ceric ion initiation was studied under homogeneous conditions in 2% acetic acid solution. The grafted polymer was characterized by FT‐IR, ¹H‐NMR, TGA and XRD and swelling studies. TGA results showed that the incorporation of TMSPM to the chitosan chains decreased the thermal stability of the grafted chitosan. Due to the grafting of TMSPM, the crystallinity of chitosan derivatives was found to be destroyed. The solubility of the grafted chitosan in water was improved. The effects of reaction conditions such as initiator concentration, monomer concentration, reaction temperature and reaction time were studied by determining the grafting parameters such as grafting and grafting efficiency. Under optimum conditions, the grafting parameters were achieved as 1440 and 97%, respectively.