Search

We report a series of novel poly(ethylene terephthalate) (PET) copolymers with improved properties through the incorporation of bioadvantaged dimethyl 2,7-naphthalenedicarboxylate (2,7-N) as a comonomer. PET is among the most commonly used engineering thermoplastics, ubiquitous in the food packaging industry. However, its application is limited by poor thermal (low Tg) and oxygen barrier performance. A series of poly(ethylene terephthalate-stat-2,7-naphthalate) copolymers were synthesized from ethylene glycol (EG), terephthalic acid (TPA), and 2,7-N via a standard two-step melt polycondensation reaction. The 2,7-N significantly improved the thermal, mechanical, and barrier properties. The glass transition temperature (Tg> 75.4 °C) and thermal stability (Td,5%> 405.1 °C) of the copolymers increase monotonically with 2,7-N content, exceeding those of PET (Tg= 69.7 °C, Td,5%= 401.4 °C). Moreover, the mechanical properties and the crystallization behaviors are tunable through the 2,7-N loading. Composition-optimized copolymers showed an increase of 70% and 200% in elongation at break and tensile strength, respectively. In addition, the oxygen permeability value of the copolymers containing 20% 2,7-N loading fell to PO2= 0.0073 barrer, a 30% improvement over that of PET. These results illustrate that the novel substitution patterns offered by biobased chemicals can translate to performance advantages in packaging materials. Finally, the fundamental structure–property relationships connecting the bioadvantaged chemicals as the comonomers to the product performance were constructed as a guide for value-added renewable polymers in the future.

Ongoing studies have developed strategies for identifying key bioactive compounds and chemical profiles in Echinacea with the goal of improving its human health benefits. Antiviral and antiinflammatory-anti-pain assays have targeted various classes of chemicals responsible for these activities. Analysis of polar fractions of E. purpurea extracts showed the presence of antiviral activity, with evidence suggesting that polyphenolic compounds other than the known HIV inhibitor, cichoric acid, may be involved. Anti-inflammatory activity differed by species, with E. sanguinea having the greatest activity and E. angustifolia, E. pallida, and E. simulata having somewhat less. Fractionation and studies with pure compounds indicate that this activity is explained, at least in part, by the alkamide constituents. Ethanol extracts from Echinacea roots had potent activity as novel agonists of TRPV1, a mammalian pain receptor reported as an integrator of inflammatory pain and hyperalgesia and a prime therapeutic target for analgesic and antiinflammatory drugs. One fraction from E. purpurea ethanol extract was bioactive in this system. Interestingly, the antiinflammatory compounds identified to inhibit prostaglandin [E.sub.2] production differed from those involved in TRPV 1 receptor activation. KEY WORDS Alkamide, antiinflammatory, antipain, antiviral, cichoric acid, Echinacea, Echinacea angustifolia, Echinacea pallida, Echinacea purpurea, Echinacea sanguinea, Echinacea simulate, HIV, TRPV1 receptor

The interaction of nucleic acids with their molecular targets often involves structural reorganization that may traverse a complex folding landscape. With the more recent recognition that many RNAs, both coding and noncoding, may regulate cellular activities by interacting with target molecules, it becomes increasingly important to understand how nucleic acids interact with their targets and how drugs might be developed that can influence critical folding transitions. We have extensively investigated the interaction of the Spinach2 and Broccoli aptamers with a library of small molecule ligands modified by various extensions from the imido nitrogen of DFHBI [(Z)-5-(3,5-difluoro-4-hydroxybenzylidene)-2,3-dimethyl-3,5-dihydro-4H-imidazol-4-one] that reach out from the Spinach2 ligand binding pocket. Studies of the interaction of these compounds with the aptamers revealed that polyfluorophenyl-modified ligands initiate a slow change in aptamer affinity that takes an extended time (half-life of ∼40 min) to achieve. The change in affinity appears to involve an initial disruption of the entrance to the ligand binding pocket followed by a gradual transition to a more defined structure for which the most likely driving force is an interaction of the gateway adenine with a nearby 2′OH group. These results suggest that polyfluorophenyl modifications might increase the ability of small molecule drugs to disrupt local structure and promote RNA remodeling.

Dihydro eurotiumide B was prepared from a 5-phenylthiobutenolide via a tandem annulation/reductive thiolation reaction.

(Z)-5-(3,5-Difluoro-4-hydroxybenzylidene)-2,3-dimethyl-3,5-dihydro-4H-imidazol-4-one (DFHBI) and its analogues are fluorogenic molecules that bind the Spinach aptamer (a small RNA molecule), which was selected for imaging RNA. They are extremely weakly fluorescent in liquid solvents. It had been hypothesized that photoisomerization is a very efficient nonradiative process of deactivation. We show, consistent with the results of other studies, that if the isomerization is impeded, the fluorescence signal is enhanced significantly. In addition, we provide a thorough characterization of the photophysical behavior of DFHBI and its derivatives, notably that of (Z)-5-(3,5-difluoro-4-hydroxybenzylidene)-2-methyl-3-((perfluorophenyl)methyl)-3,5-dihydro-4H-imidazol-4-one (PFP-DFHBI) in various solvent environments. Solvent-dependent studies were performed with various mixtures of solvents. The results suggest that hydrogen bonding or strong interactions of the solvents with the phenolic-OH group change the absorption band near 420–460 nm and the nature of emission near 430 and 500 nm through various degrees of stabilization and the transformation between the neutral and the anionic species at both ground and excited states. These observations are confirmed by using a methoxy-substituted molecule ((Z)-5-(4-methoxybenzylidene)-2,3-dimethyl-3,5-dihydro-4H-imidazol-4-one), where the 420–460 nm band is absent in the presence of methanol and the spectra are similar to those of PFP-DFHBI in noninteracting solvents, such as acetonitrile and dichloromethane. Thus, in addition to the major role of photoisomerization as a nonradiative process of deactivation of the excited state, the fluorescence of DFHBI-type molecules is very sensitively dependent upon the pH of the medium as well as upon solvent-specific interactions, such as hydrogen-bonding ability and polarity.

Naphthacemycin A9was synthesized in nine steps by a sequence featuring a Diels–Alder reaction of a hindered aryl butadiene and a Hauser–Kraus annulation reaction.

A mild procedure for the low-temperature conversion of alkynes to diketones has been developed and employed in the synthesis of AI-2.

A direct synthesis of trimellitic anhydride (TMA) and hemimellitic anhydride (HMA) has been reported in which all the carbons of TMA and HMA are derived from malic acid. Acetoxy succinic anhydride represents a convenient in situ equivalent of maleic anhydride.

Diels–Alder reactions of quinones 4, 7, and 15 exhibit remarkable regioselectivity. In contrast, the Diels–Alder reaction of quinone 12 showed no regioselectivity, indicating that the regioselectivities are due to electronic interactions. The selectivity is nicely explained using molecular electrostatic potentials. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

The reaction of ketone enolates with phosphonate aldehydes afforded cyclopentenols or cyclohexenols in a one-pot procedure. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Lipofuscin is a yellow‐brown, highly fluorescent pigment that undergoes an age‐related progressive accumulation in animal cells, mainly in postmitotic cells. It is a heterogeneous, high‐molecular weight material associated with proteins, lipids and nucleic acids. Lipofuscin is implicated in many aspects of human health, including aging, oxidative stress, macular degeneration, lipid peroxidation, atherosclerosis, dementia (Alzheimer's Disease) and diseases associated with prions. Although the fluorescent properties of lipofuscin have long been recognized, neither histologists nor chemists have yet isolated the pigments themselves or characterized their optical properties. We have prepared lipofuscinlike species by reacting malondialdehyde (MDA) with cysteine (Cys). MDA: Cys adducts 3:2 and 2:2 are two of those that have been identified among the many that were present in the reaction. Whereas previous attempts to synthesize lipofuscinlike species resulted in compounds that were either nonfluorescent or emitted principally in the blue, the MDA: Cys adducts reported in this study are not only fluorescent but also emit over a broader range.

The pyrrolo[2,1-c][1,4]benzodiazepine and dibenzo[b,e][1,4]diazepine skeletons were rapidly generated from salicylic acids. The key step in these syntheses was the substitution of an aryl triflate.

Juglomycin A has been synthesized in six steps from juglone.

An approach to the ABC ring system of aquayamycin which incorporates a selectively protected cis-diol unit is described. The key step is an intramolecular addition of the anion of a protected cyanohydrin to a ketone.

The selective chlorimation of anhydrides can be effected by the reaction of sulfuryl chloride and dibenzoyl peroxide. The direct transformation of 2and 6into precursors to β-lactam antibiotics and the kainic acids described.

The proposition that covert roles within a group are assigned to individual group members based on their propensity to verbally or nonverbally express certain patterns of unwanted, disowned, and projected emotions that are experienced as threatening by other members is examined. The analysis focuses on (a) articulating a model for describing how group members' emotions are collectively projected into a single member, resulting in covert roles; (b) describing a method for analyzing covert roles; and (c) presenting researchable propositions derivable from the model of covert role analysis.

The photoenolization/Diels-Alder sequence provides a direct preparation of quinone 2 which exhibited activity against SR leukemia and colon cancers.

The preparation of a bicyclic amino ketone for the synthesis of huperzine has been achieved in only six steps. The key step is the introduction of the primary amine moiety via a bridgehead enone.

In conjunction with quassinoid model studies we required dienones such as 1 or their derived dienols for use in Diels-Alder reactions. No general synthetic routes to this class of [image omitted] compounds have to our knowledge been reported. A recent comprehensive review on alkoxy dienes1 does not contain a single example of a diene with this substitution pattern. After some unsuccessful efforts, we initiated the sequence of reactions shown below. The reaction of ethoxyvinyl lithium2 with 3-ethoxy-2-cyclohexenone [image omitted] proceeded i n excellent yield. We recognized that the hydrolysis of 2 could present a problem since the acidic hydrolysis of both 3-alkoxy allylic alcohols3 and 2-alkoxy allylic alcohols4 is known to afford conjugated enones. Moreover, the [image omitted] conditions must be sufficiently mild that the enol ether in the product is not affected. Various aqueous acid condition3,4 provided mixtures of products. However, silica gel chromatography of alcohol 2 produced dienone 1 in 94% yield from 3-ethoxy-2-cyclohexenone! Reduction of 1 in ether at 0°C followed by basic workup furnished the unstable alcohol 3 in 43% yield. We have investigated the generality of this sequence with representative enones. The results of our study are illustrated in Table I. The results display an interesting dichotomy between the cyclic and acyclic examples. The failure of the acyclic alcohols to provide useful yields of the desired products may be ascribed to difficulties in achieving a suitable conformation for reaction. Inspection of molecular models supports this suggestion.

An efficient procedure for attaching the methylsuccinimidobenzoate ester unit to an ABE ring segment of methyllycaconitine is described.

The reaction of quinones with in situ generated acyl- or carboxamido radicals provides a direct route to the synthesis of acylhydroquinones not accessible by the photochemical reaction of quinones with aldehydes.

Recent methodology employing sulfone chemistry indicates that sulfones are becoming widely recognized as versatile intermediates in organic chemistry.1 In particular, the anions of allylic sulfones have proven especially valuable for the synthesis of vitamin A,2 chrysanthemic acid3 and presqualene alcohol.4 In the latter two cases the allylic sulfone anion added by a conjugate addition to an unsaturated ester to afford, after elimination of sulfinate anion, a cyclopropyl ester. We wish to report that Michael additions of allylic sulfone anions generated at -78d`C with n-butyl lithium provide high yields of sulfone adducts with unsaturated ketones and esters. The results of our study are compiled in the Table below. One striking feature of this Table is the regiochemical purity of the resulting adducts. The contrast between acyclic Michael acceptors and cyclohexenone is also quite

The synthesis of compounds 5 and 8 from haloarylindoles via both radical and palladium-mediated routes is described. In each case the palladium-based procedure afforded better yields.

Azlactone 4 reacted with dienes to afford Diets-Alder adducts in good to excellent yields.

The reductive methylation of quinones bearing electron donating groups such as hydroxyl or alkoxyl groups proceeds in good yields. The improved conditions greatly extend the scope of this useful reaction.

During the course of synthetic studies, the preparation of hydroxy quinones such as 1 became necessary. Existing methodology1 is plagued with problems associated with regioselectivity and overoxidation.

The reaction of bromodiester 6 with base in liquid ammonia affords good yields of aminocyclopropane diesters 8 and 9. The corresponding diacids were not inhibitors of AAT.

The irradiation of 2-ethoxy-1,4-naphthoquinone with allyl alcohol and 3-butenol affords diols containing the novel spiro[3.3]heptane unit.

Iodostannyl esters react with alkenes in the presence of AIBN to afford γ-lactones.

Utilizing the dimensions of Initiating Structure and Consideration developed by Halpin, the present investigation examined the idiosyncratic effects of implicit theories of leadership. The importance of Consideration and Initiating Structure behavior as components of implicit theories of leadership held by 153 college students was predicted to relate to their evaluations of a leader's effectiveness and the responsibility attributed to a leader for a successful group outcome. A leader whose written description emphasized Consideration behavior was judged to be more effective and more responsible for an alleged group success in proportion to the importance respondents placed on Consideration behavior in their implicit theories of leadership. The leader who emphasized Consideration behavior was also judged less effective in proportion to the importance respondents placed on Initiating Structure behavior in their implicit leadership theories. Results also indicated that a leader who emphasized Initiating Structure behavior was attributed responsibility for an alleged group success in proportion to the extent to which the respondents considered Initiating Structure Behavior to be of major importance in their implicit theories of leadership.

The reaction of bromoketones with organocuprates and lithium 2,6-ditert-butyl-4-methylphenoxide in ether affords good to excellent yields of ketones. The alkyl or alkenyl group is introduced via a conjugate addition to an in situ derived bridgehead enone.

In 1876 Zumier1 and Czapek2 each reported the occurrence of fructose in the urine of a nondiabetic patient. Though it is clear that in both cases fructose was present in the urine, there are insufficient data in the reports of these authors to warrant the conclusion that they were dealing with instances of the syndrome of essential fructosuria. Since 1876 there have appeared some thirty-seven reports describing 55 cases of essential fructosuria (table 1). Of these, sixteen do not give sufficient data to confirm the diagnosis.Though several of the more recent reports contain some experimental results, there has as yet been none which substantiates an explanation of the mechanism of essential fructosuria. This paper reports the cases of 2 brothers with essential fructosuria, together with some experimental results leading toward a possible explanation of the mechanism of this condition. REPORT OF CASES Case 1.—A. G., a 7

A direct synthesis of analogues 6and 7is described. The key transformations are the addition of dibromomethyl lithium to a ketone and the subsequent mild hydrolysis to a hemiacetal.

Compounds 3and 5are the first phenanthrenequinones to exhibit significant virucidal activity against the retrovirus equine infectious anemia virus. They differ from hypericin in that their virucidal activity is not light dependent.

Ginkgolic acids were directly synthesized from 6-methylsalicylic acid using a sequence involving protection of the phenol and acid as methoxymethyl ethers and esters, lateral alkylation and deprotection under mild aqueous acid conditions.

Antileukemic pyrone 1 was synthesized by way of a five-step procedure from 4-Hydroxy-5-methoxycarbonyl-6-methyl-2-pyrone (8). This is the first synthesis of 4-methoxy-6-methyl-5-(3-oxobutyl)-2H-pyran-2-one (1).

A hydride abstraction strategy can be used to make anthocyanidins and isoflavylium salts from benzopyrans in good yields.

A flexible synthesis of the azafluorenone alkaloids 1, 2, 3, and 4is described.

An aldol condensation and an Algar−Flynn−Oyamada oxidative cyclization were key steps in the direct synthesis of chrysosplenol D, an efflux pump inhibitor that can potentiate the activity of commercially important antibiotics and antimalarials.

Demethyl mycosporulone was synthesized from the methyl ester of dihydro anisic acid in six steps. The key steps included an aldol/oxidation sequence and the formation of the exomethylene group by dehydration using Burgess salt.

The title compound, 3,3a,5,5a,6,7,8,9‐octahydro‐3a‐hydroxy‐5a‐methyl‐8‐(2‐prop­enyl)­furo­[3,2‐c]­iso­benzo­furan‐2‐one, C14H20O4, crystallizes with two independent molecules in the asymmetric unit. The molecules have similar metric parameters but differ in the conformations of the isopropenyl groups. The hydroxyl groups form one‐dimensional chains of hydrogen bonds.

Furomollugin was synthesized in three steps from commercially available starting materials using phthalide annulation chemistry.