Simple Esters Research Articles

Free Radical Addition of Nitrile, Ketone, and Ester to Alkyne and the Selectivity Discussion.

A general and practical atom transfer radical addition (ATRA) of simple nitriles, ketones, and esters to alkynes was developed. It can allow an efficient access to a wide range of β,γ-unsaturated nitriles, ketones, and esters. The unique chemoselectivity in this system is also discussed.

Multiple In vitro biological effects of phenolic compounds from Morus alba root bark.

Morus alba L. is used in traditional Chinese medicine for the treatment of various diseases, including bacterial infections and inflammation. As a rich source of phenolic compounds, the plant is an object of many phytochemical and pharmacological studies. The aim of the study was to isolate and evaluate possible parallel antiviral, antibacterial, and anti-inflammatory activities of phenolic mulberry compounds. Extensive chromatographic separation of mulberry root bark extract and in vitro biological screening of 26 constituents identified promising candidates for further pharmacological research. Selected compounds were screened for anti-infective and anti-inflammatory activities. Antiviral activity was determined by the plaque number reduction assay and by the titer reduction assay, antibacterial using broth microdilution method, and anti-inflammatory activity using COX Colorimetric inhibitor screening assay kit. One compound was evaluated in vivo in carrageenan-induced paw-edema in mice. Five prenylated compounds 1, 2, 8, 9, and 11, together with a simple phenolic ester 13, exhibited inhibitory activity against the replication of herpes simplex virus 1 (HSV-1) or herpes simplex virus 2 (HSV-2), with IC50 values ranging from 0.64 to 1.93 μg/mL, and EC50 values 0.93 and 1.61 μg/mL. Molecular docking studies demonstrated the effects of the active compounds by targeting HSV-1 DNA polymerase and HSV-2 protease. In antibacterial assay, compounds 1, 4, 11, and 17 diminished the growth of all of the Gram-positive strains tested, with MIC values of 1-16 μg/mL. The anti-inflammatory ability of several compounds to inhibit cyclooxygenase 2 (COX-2) was tested in vitro, and compound 16 displayed greater activity than the indomethacin, positive control. Mulberrofuran B (11) showed anti-inflammatory activity in vivo against carrageenan-induced paw-edema in mice. Experimental investigation showed promising antiviral, antibacterial, and/or anti-inflammatory activities of the phenolic mulberry constituents, often with multiple inhibitory effects that might be used as a potential source of new medicine.

Photochemically-Mediated, Nickel-Catalyzed Synthesis of N-(Hetero)aryl Sulfamate Esters.

A general method is described for the coupling of (hetero)aryl bromides with O-alkyl sulfamate esters. The protocol relies on catalytic amounts of nickel and photoexcitable iridium complexes and proceeds under visible light irradiation at ambient temperature. This technology engages a broad range of simple and complex O-alkyl sulfamate ester substrates under mild conditions. Furthermore, it is possible to avoid undesirable N-alkylation, which was found to plague palladium-based protocols for N-arylation of O-alkyl sulfamate esters. These investigations represent the first use of sulfamate esters as nucleophiles in transition metal-catalyzed C-N coupling processes.

Descriptors for terpene esters from chromatographic and partition measurements: Estimation of human odor detection thresholds

We have used gas chromatographic retention data together with other data to obtain Abraham descriptors for 30 terpene esters. These include the air-water partition coefficient, as log Kw, for which no experimental values are available for any terpene ester. The other descriptors are the ester dipolarity, S, the hydrogen bond basicity, B, (the ester hydrogen bond acidity is zero for the esters studied), and L the logarithm of the air-hexadecane partition coefficient. Both S and B are larger than those for simple aliphatic esters, as expected from the terpene ester structures that include ring systems and ethylenic double bonds. These descriptors can then be used to obtain a large number of physicochemical and environmental properties of terpene esters. We have analyzed experimental results on human odor detection thresholds and have constructed another equation for the calculation of these thresholds, to go with a previous equation that we have reported. Then the descriptors for terpene esters can be used to estimate the important odor detection thresholds.

Enantioselective [2+2] Cycloadditions of Cinnamate Esters: Generalizing Lewis Acid Catalysis of Triplet Energy Transfer.

We report the enantioselective [2+2] cycloaddition of simple cinnamate esters, the products of which are useful synthons for the controlled assembly of cyclobutane natural products. This method utilizes a cocatalytic system in which a chiral Lewis acid accelerates the transfer of triplet energy from an excited-state Ir(III) photocatalyst to the cinnamate ester. Computational evidence indicates that the principal role of the Lewis acid cocatalyst is to lower the absolute energies of the substrate frontier molecular orbitals, leading to greater electronic coupling between the sensitizer and substrate and increasing the rate of the energy transfer event. These results suggest Lewis acids can have multiple beneficial effects on triplet sensitization reactions, impacting both the thermodynamic driving force and kinetics of Dexter energy transfer.

Does the Exception Prove the Rule? A Comparative Study of Supramolecular Synthons in a Series of Lactam Esters

In this paper a series of simple lactam esters and carboxylic acids is studied with respect to their overall conformation and hydrogen bonding patterns. In total, eight lactams featuring Nα-substitution have been synthesized. Additionally, the molecular structures of related lactam esters have been considered. The length of the amide bonds does not seem to be majorly influenced by different substituents unless the electron withdrawing N-Boc-protection group is introduced, resulting in a higher susceptibility toward hydrolytic ring opening. As known from other lactams, the Nα ester moiety of the title compounds can be in an axial or equatorial conformation. Smaller ester groups were found to prefer equatorial positions, while larger ones occupy axial sites. N-substitution seems to promote axial conformations of the respective Nα group, with enantholactams being the only studied exception. In addition to the two common amide packing motifs, i.e., the R22(8) amide dimer (NH···O/NH···O) and the C(4) amide chain, a third graph-set was found: the R22(8) NH···O/CH···O═C heterodimer. In general, there seems to be a tendency for medium-sized lactams as well as lactams with small esters to form R22(8) amide dimers. Larger esters and enantholactam esters lead to C(4) amide chains. In this respect the formation of R22(8) N—H···O/C–H···O═C heterodimers should be seen as a remarkable exception.

Few layer 2D pnictogens catalyze the alkylation of soft nucleophiles with esters

Group 15 elements in zero oxidation state (P, As, Sb and Bi), also called pnictogens, are rarely used in catalysis due to the difficulties associated in preparing well–structured and stable materials. Here, we report on the synthesis of highly exfoliated, few layer 2D phosphorene and antimonene in zero oxidation state, suspended in an ionic liquid, with the native atoms ready to interact with external reagents while avoiding aerobic or aqueous decomposition pathways, and on their use as efficient catalysts for the alkylation of nucleophiles with esters. The few layer pnictogen material circumvents the extremely harsh reaction conditions associated to previous superacid–catalyzed alkylations, by enabling an alternative mechanism on surface, protected from the water and air by the ionic liquid. These 2D catalysts allow the alkylation of a variety of acid–sensitive organic molecules and giving synthetic relevancy to the use of simple esters as alkylating agents.

Anti-Inflammatory and Neuroprotective Effects of DIPOPA (N,N-Diisopropyl-2-Oxopropanamide), an Ethyl Pyruvate Bioisoster, in the Postischemic Brain.

Ethyl pyruvate (EP) is a simple aliphatic ester of pyruvic acid and has been shown to have protective properties, which have been attributed to its anti-inflammatory, anti-oxidative, and anti-apoptotic functions. In an effort to develop better derivatives of EP, we previously synthesized DEOPA (N,N-diethyl-2-oxopropanamide, a novel isoster of EP) which has greater neuroprotective effects than EP, probably due to its anti-inflammatory and anti-excitotoxic effects. In the present study, we synthesized 3 DEOPA derivatives, in which its diethylamino group was substituted with diisopropylamino, dipropylamino, or diisobutylamino groups. Among them, DIPOPA (N,N-diisopropyl-2-oxopropanamide) containing diisopropylamino group had a greater neuroprotective effect than DEOPA or EP when administered intravenously to a rat middle cerebral artery occlusion (MCAO) model at 9h after MCAO. Furthermore, DIPOPA had a wider therapeutic window than DEOPA and a marked reduction of infarct volume was accompanied by greater neurological and behavioral improvements. In particular, DIPOPA exerted robust anti-inflammatory effects, as evidenced by marked suppressions of microglia activation and neutrophil infiltration in the MCAO model, in microglial cells, and in neutrophil-endothelial cocultures at lower concentration, and did so more effectively than DEOPA. In particular, DIPOPA remarkably suppressed neutrophil infiltration into brain parenchyma, and this effect was attributed to the expressional inhibitions of cell adhesion molecules in neutrophils of brain parenchyma and in circulating neutrophils via NF-κB inhibition. Together, these results indicate the robust neuroprotective effects of DIPOPA are attributable to its anti-inflammatory effects and suggest that DIPOPA offers a potential therapeutic means of ameliorating cerebral ischemic injury and other inflammation-related pathologies.

Effect of Biocompatible Esters and Alcohols as Cosurfactants on Structure and Solubilization Behavior of the Zwitterionic Surfactant Tetradecyldimethylamine Oxide

In this work, we compare the effect of different monoterpenoid alcohols that differ with respect to their number of double bonds and simple aromatic esters of variable molecular architecture as cosurfactants on the phase behavior of the zwitterionic surfactant tetradecyldimethylamine oxide (TDMAO) and its solubilization behavior, with respect to decane as a model paraffin oil. The esters are shown to be potent cosurfactants but require higher concentrations to achieve similar effects, with respect to structural changes and solubilization enhancement. Compared to the alcohols, they solubilize somewhat smaller amounts of decane, do reduce the interfacial tension substantially less, and also do not form an isotropic phase of unilamellar vesicles (L4) but directly multilamellar vesicles (Lαl). A very interesting effect is the significance of the detailed molecular architecture of the esters, as ethyl benzoate and benzyl acetate, both having the same sum formula, differ significantly, with respect to their cos...

The phosphinoboration of 2-diphenylphosphino benzaldehyde and related aldimines

We have investigated the addition of a simple phosphinoboronate ester, Ph2PBpin (pin = 1,2-O2C2Me4), to 2-diphenylphosphinobenzaldehyde (2-Ph2PC6H4C(O)H) and related aldimine derivatives (2-Ph2PC6H4C(NR)H) as a simple and effective strategy for generating unique diphosphine ligands bearing a pendant Lewis-acid Bpin group. These reactions proceed selectively to give one new product where the phosphide fragment has added to the aldehyde (or imine) carbon atom and the electron-deficient boron group has added to the electron-rich heteroatom. Preliminary studies show these new compounds can ligate to Pd(II) and Pt(II) metal centres. These novel metal complexes, as well as the organic soluble [MCl2(coe)]2 (M = Pd, Pt, coe = cis-cyclooctene) compounds, have been shown to be effective precatalysts in the cyclisation of alkynoic acids to give the corresponding exo-dig cyclic lactones. Reactions employing these metal complexes also generated unusual endo-dig cyclic lactones not traditionally observed in these cyclisation reactions. For instance, reactions of 4-pentynoic acid also afforded significant amounts of α-angelica lactone, a biologically-important compound traditionally prepared via the catalytic dehydration and cyclisation of levulinic acid.

Microbial esterases and ester prodrugs: An unlikely marriage for combating antibiotic resistance.

The rise of antibiotic resistance necessitates the search for new platforms for drug development. Prodrugs are common tools for overcoming drawbacks typically associated with drug formulation and delivery, with ester prodrugs providing a classic strategy for masking polar alcohol and carboxylic acid functionalities and improving cell permeability. Ester prodrugs are normally designed to have simple ester groups, as they are expected to be cleaved and reactivated by a wide spectrum of cellular esterases. However, a number of pathogenic and commensal microbial esterases have been found to possess significant substrate specificity and can play an unexpected role in drug metabolism. Ester protection can also introduce antimicrobial properties into previously nontoxic drugs through alterations in cell permeability or solubility. Finally, mutation to microbial esterases is a novel mechanism for the development of antibiotic resistance. In this review, we highlight the important pathogenic and xenobiotic functions of microbial esterases and discuss the development and application of ester prodrugs for targeting microbial infections and combating antibiotic resistance. Esterases are often overlooked as therapeutic targets. Yet, with the growing need to develop new antibiotics, a thorough understanding of the specificity and function of microbial esterases and their combined action with ester prodrug antibiotics will support the design of future therapeutics.

Synthesis of cis-hydrindan-2,4-diones bearing an all-carbon quaternary center by a Danheiser annulation.

A straightforward synthetic entry to functionalized hydrindane compounds based on a rapid assembly of the core nucleus by a Danheiser cycloaddition is reported. Valuable bicyclic building blocks containing the fused five and six-membered carbocyclic ring system can be achieved in only four steps from a simple acyclic β-keto ester.

Read-across of 90-day rodent repeated-dose toxicity: A case study for selected simple aryl alcohol alkyl carboxylic acid esters

Aryl alcohol alkyl carboxylic acid esters constitute a wide-employed class of fragrance materials. Outcomes presented within this study illustrate formulation of a read-across protocol for 90-day, repeat-dose toxicity within a series of these compounds, extending in scope to the dodecanoic acid esters of both benzyl and 2-phenylethyl alcohol. Central to the filling of data gaps is the hypothesis that adverse impact – mediated through mechanisms analogous to narcosis-associated non-specific basal cytotoxicity – is as a consequence of the hydrolysis of parent compounds to their corresponding alcohol. High-quality in vivo data (equivalent to either OECD Test Guideline 408 or 411) relating the toxicodynamic and toxicokinetic profiles of benzyl alcohol, 2-phenylethyl alcohol and benzyl acetate within rodents were retrieved, permitting extrapolation to each ester derivative with great confidence. NOAEL values of 250–500 mg/kg/day were assigned to esters, with a greater toxicity present within females. In order to greater enhance reliability, further theoretical support for the read-across prediction is provided through the integration, where appropriate, of in vitro and in silico data.

Convenient synthesis of N-substituted β-lactam-4-carboxylates

When simple β-amino esters were treated with cyanate ion, dihydrouracils were formed. However, the presence of the α-carboxylate group in aspartic ester substrates hinders the formation of the pyrimidine ring. Instead, treatment of aspartic esters with carbonate bases yields N-substituted β-lactam-4-carboxylates in excellent yields, representing a green, convenient, and efficient synthesis of these biologically interesting molecules.

Polymer ready for repeat recycling

Developing a practical polymer that can break down to its monomer and then be repolymerized over and over again has been a long-standing goal of plastics makers and recycling advocates. Such a material would dramatically cut down the need for virgin feedstocks and would vastly improve the life cycle of plastics. While repeatedly recyclable polymers have been made, their properties simply aren’t as good as those of commonly used plastics—until now. Chemists Eugene X.-Y. Chen, Jian-Bo Zhu, Eli M. Watson, and Jing Tang at Colorado State University have created a recyclable polymer with mechanical strength and thermostability that’s comparable to popular plastics. A few years ago, Chen and his group reported they were able to make a polymer from the ring-opening reaction of γ-butyrolactone—a simple five-membered cyclic ester previously thought to be impervious to polymerization for thermodynamic reasons. They thought they could create a sustainable, recyclable polymer by using this

N-Heterocyclic Carbene Catalyzed Enantioselective [3 + 2] Dearomatizing Annulation of Saturated Carboxylic Esters with N-Iminoisoquinolinium Ylides.

The dearomatizing annulation reaction is a significant challenge in organic chemistry. The direct activation of α-carbons of simple saturated esters, as nucleophiles, is an important synthesis strategy. In the present study, we disclose [3 + 2] dearomatizing annulation reactions with direct activating α-carbons of saturated carboxylic esters and N-iminoisoquinolinium ylides, which possess highly enantioselective characteristics, catalyzed by N-heterocyclic carbenes (NHCs). The protocol achieves isoquinoline dearomatization and the construction of tricyclic chiral products under mild conditions with good yield, substrate tolerance, and diastereoselectivity as well as excellent enantioselectivity.

Traditional Uses, Pharmacological Action and Phytochemical Analysis of Carissa carandas Linn.: A Review

Starting from immemorial time; peoples traditionally used herbs and plants to treat different human and animals ailments. This initiated scientists to investigate on traditional medicinal plants and herbs for biological activities by checking through bioassay and then isolating the bioactive constituents from biologically active medicinal plants and herbs. The different parts of Carissa carandas have been used for various human ailments. It has been used by traditional healers in the treatment of scabies, intestinal worms, pruritus, biliousness, snake-bite/poisoning, astringent, anemia, stomachache, diarrhea, rheumatism, earache, anthelmintic, female libido, hyperdipsia, anorexia, intermittent, mouth ulcer and sore throat, syphilitic pain, burning sensation fever, biliary dysfunction and also used as appetizer, antimicrobial, anti-fungal, analgesic, anti-inflammatory and anti-scorbutic. Its biological activities have been reported by different researchers as hepatoprotective, neuropharmacological, anticancer, antioxidant, anticonvulsant, antiulcer, anthelmintic, analgesic, anti-inflammatory, cardiovascular, antinociceptive, anti-diabetic, anti-pyretic, cardiotonic, histamine releasing, DNA damage inhibition, constipation, anti-diarrheal, antihyperlipidemic, antibacterial, antiviral, cytotoxic potential and diuretic. Its phytochemical constituents which impart medicinal value to the plant was reported as alkaloids, carbohydrates, glycosides, unsaturated sterols, phenolics, saponins, flavonoids, steroids, triterpenoids, tannins, proteins, cardiac glycosides, phytosterol, phlobatannins, leucoanthocyanin, chalcones, coumarin, anthracyanin, emodin, minerals acids, vitamins and anthraquinone glycosides. So far 14 compounds have been isolated from roots, 40 compounds from fruits and 19 compounds from leafs. These compounds include phenolic, alkaloids, sterols, terpenoids, simple acids, simple ester, sesquiterpenes, carboxylate, amino acids, glucose and galactose, sterols glycosides, phenolic lignin. Hence we reviewed the traditional uses, extraction methods, pharmacological uses and phytochemical constituents of Carissa carandas.

A KI-mediated radical anti-Markovnikov addition of simple ketones/esters to unactivated alkenes

A KI-mediated radical anti-Markovnikov addition of simple ketones and esters to unactivated alkenes was developed.

Transterification of Used Cooking Oil and Jatropha Oil: Standardization of Process Parameters and Comparision of Fuel Characteristics

Biodiesel, which is made from renewable sources, consists of the simple alkyl esters of fatty acids.A two-step transesterification process was used to prepare methyl esters from high free fatty acid (FFA) non-edible oils In the present study, influence of key parameters like methanol/oil molar ratio, catalyst concentration, reaction temperature and reaction time were determined and compared for Used Cooking Oil(UCO) and Jatropha oil. Gas chromatography mass spectroscopy(GC-MS) and elemental analysis were analyzed. Physical and chemical properties of biodiesel are influenced by the structural features of fatty acid, and are compared with the biodiesel standards (ASTM D6751)

Novel agrochemical conjugates with self-assembling behaviour

Hypothesis: That conjugation of agrichemicals to pro-assembly hydrophobic moieties will enable enhanced compatibility and loading with host lyotropic liquid crystalline carrier matrix, and potentially self-assemble in their own right in aqueous environments. Experiments: A series of lipid-like agrochemical-conjugates were synthesized using specific amphiphilic entities conjugated onto the agrochemicals, picloram and 2,4-dichlorophenoxyacetic acid (2,4-D). The self-assembly behaviour and compatibility of the novel entities when incorporated into phytantriol and monoolein-based liquid crystalline systems were examined using small angle X-ray scattering, cryo-TEM and polarized optical microscopy. Findings: Compared to agrochemical-conjugates with simple alkyl ester groups, the esterification of the agrochemicals with amphiphilic groups such as phytantriol and monoolein led to greater structural compatibility and consequently a greater loading of the agrochemicals in the liquid crystalline systems without destabilizing phase structure. Picloram-monoolein and picloram-monoelaidin can self-assemble to form lamellar structures in water. However, certain agrochemical-conjugates such as picloram-monoelaidin and picloram-PEGn-oleate showed poor compatibility with liquid crystalline systems, resulting in phase separation.