Ylic Acid Research Articles

ChemInform Abstract: Palladium‐Catalyzed Alkoxycarbonylation of Conjugated Dienes under Acid‐Free Conditions: Atom‐Economic Synthesis of β,γ‐Unsaturated Esters.

Carbonylation reactions constitute important meth- odologies for the synthesis of all kinds of carboxylic acid derivatives. The development of novel and better catalysts for these transformations is of interest for both academic and industrial research. Here, a benign palladium-based catalyst system for the alkoxycarbonylation of conjugated dienes under acid-free conditions has been developed. This atom-efficient transformation provides straightforward access to a variety of b,g-unsaturated esters in good to excellent yields and often with high selectivities. As an industrially relevant example the (formal) synthesis of dimethyl adipate and e-caprolactam from 1,3-butadiene is demonstrated. Alkene carbonylations are among the most important homogeneously catalyzed processes in industry. (1) Within this class of reactions, alkoxycarbonylations, also called hydroesterifications, represent a straightforward method for the conversion of olefins, CO, and alcohols into the corre- sponding esters. (2) In this respect, the transition-metal-cata- lyzed carbonylation of allylic compounds is of considerable interest for the synthesis of versatile b,g-unsaturated carbox- ylic acid derivatives. (3) In the past, effective carbonylation methods for reactions of allylic carbonates, (4) acetates, (5)

Pteridine Detection in Urine: the future of Cancer Diagnostics?

Pteridines as biomarkers The aim of developing noninvasive cancer screening techniques that can lead to both diag­ nosis and prognosis is rapidly gaining popular­ ity in cancer biomarker research and discov­ ery. Accordingly, the field of cancer biomarker research is experiencing a shift from more tra­ ditional antigenic and proteomic approaches to the promising outlet of metabolic diagnostics. Indeed, the discovery of a family of related com­ pounds that can be implicated in multiple can­ cers at different stages is highly desirable. One instance where these goals may be realized lies in the class of compounds known as pteridines. Assigning pteridines as potential biomarkers for malignancy is certainly not a recent develop­ ment. Early studies examined their potential cancer­ revealing roles as early as the mid 1980s [1]. From these early studies, the biomarker literature has seen a flurry of studies conducted on assorted pteridines in further attempts to implicate them as urinary biomarkers for malignancy, spanning a wide breadth of analytical platforms including gas chromatography, liquid chromato graphy, liquid chromatography–mass spectrometry and capil­ lary electrophoresis. The findings of these studies are also quite remarkable: urinary pteridines have been implicated as potential biomarkers in a host of diseases, including breast, prostate, kidney and bladder cancers, as well as phenylketonuria [2–10]. Moreover, these studies have served to narrow the entire pteridine family down to a dozen key mem­ bers, including: xanthopterin, isoxanthopterin, pterin, 6­biopterin, 7­biopterin, pterin­6­carbox­ ylic acid, neopterin, pterin, tetrahydrobiopterin, 6­hydroxymethylpterin, 6,7­dimethylpterin and 6­methylpterin.

Graphite Oxide-Catalyzed Esterification and Transesterification

Graphite oxide (GO) was involved in the esterification of carboxylic acids with alcohols or phenols and the trans- esterification of esters with alcohols. Three types of GO prepared by different methods were screened and GO by modified Hummers method was found superior to the others. The esterification of primary and secondary alcohols afforded the corre- sponding esters in moderate to excellent yields under mild conditions. GO-catalyzed esterification of tertiary alcohols and phenols took place hardly. Moreover, GO showed highly catalytic activity for the transesterification. As a weakly acidic solid catalyst, GO is easily available, cheap, environmentally benign, and well tolerant to various functional groups. Only catalyzed by GO, the esterification of long-chain carboxylic acids and the transesterification of the glycerol ester of long-chain carbox- ylic acids underwent steadily. As such, GO-catalyzed esterification and transesterification could be used in the biodiesel prep- aration potentially. Keywords graphite oxide; catalyst; esterification; transesterification; biodiesel

ChemInform Abstract: Cobalt(II) Chloride-Catalyzed Syntheses of Acid Anhydrides from Acid Chlorides.

Abstract Acid anhydrides were synthesized by reacting acid chlorides with car☐ylic acids in the presence of catalytic quantities of cobalt(II) chloride.

Heterocycles [h]-fused to 4-oxoquinoline-3-carboxylic acid. Part VII: synthesis of some 6-oxoimidazo[4,5-h]quinoline-7-carboxylic acids and esters

A series of ethyl 2-(substituted)-9-cyclopropyl- 4-fluoro-6-oxo-1H-imidazo(4,5-h)quinoline-7-carboxylates has been prepared from ethyl 7,8-diamino-1,4-dihydro- quinoline-3-carboxylate via thermally induced reactions with model alkanoic acids or via microwave-assisted cyclocondensation with some arene carboxaldehydes. Acid-catalysed hydrolysis of the resulting ester derivatives furnished the corresponding imidazoquinoline-7-carbox- ylic acids. The structures of these new acid and ester derivatives are based on microanalytical and spectral (IR, MS, and NMR) data.

Optical Resolution by Preferential Crystallization of (1RS,3RS)‐1,2,3,4‐Tetrahydro‐6,7‐dihydroxy‐1‐methyl‐3‐isoquinolinecarbox ylic Acid.

Optical Resolution by Preferential Crystallization of (1RS,3RS)‐1,2,3,4‐Tetrahydro‐6,7‐dihydroxy‐1‐methyl‐3‐isoquinolinecarbox ylic Acid.

P.3.005 The aversive effect of a glutamate metabotropic receptor agonist injected into the dorsal periaqueductal grey may partially depend on glutamate release

The excitatory and inhibitory actions of metabotropic glutamate receptor (mGluR) agonists were investigated in acutely dissociated rat hippocampal CA3 pyramidal neurons, using the conventional whole-cell and nystatin-perforated patch recording configurations under the voltage-clamp condition. With the conventional whole-cell recording, glutamate (Glu) and quisqualic acid (QA) induced only ionotropic inward currents accompanied by increased membrane conductance at a holding potential (VH) of -45 mV. The response was reversibly blocked in the presence of D-2-amino-5-phosphonopentanoic acid (d-AP5) and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), the antagonists ofN-methyl-d-aspartate (NMDA) receptor and non-NMDA receptor, respectively. With nystatin-perforated patch recording, mGlu responses insensitive to bothd-AP5 and CNQX were observed. Fifty-five % of the cells responded by a slow inward current accompanied by conductance decrease (ImGlui) at aVH of −44 mV. One % of the neurons showed an outward current with conductance increase (ImGluo), and 34% of the neurons showedImGluo followed byImGlui. The onset ofImGluo occurred approximately 900 ms after the response to 30 mM K+. The time to peak ofImGluo were 32- to 79-times longer than those of ionotropic responses.ImGlui appeared at lower concentrations than ionotropic Glu responses, whereasImGluo appeared at similar concentrations as ionotropic responses. The rank order of affinity was QA > Glu > (±)-1-aminocyclopentane-trans-1,3-dicar☐ylic acid (tACPD) for bothImGlui andImGluo. Half-maximal effective concentrations (EC50) and the threshold concentrations for the three agonists were four- to tenfold lower forImGlui than forImGluo. The current-voltage relationship showed that the reversal potentials ofImGlui andImGluo shifted 55 and 59 mV, respectively, for a tenfold change in extracellular K+ concentration, indicating that K+ is the charge carrier of both mGlu responses. DuringImGlui, both the leakage current and muscarine-sensitive voltage-dependent K+ current (M current) were suppressed.ImGluo induced by 10−4 M tACPD was abolished by 3 · 10−7 M charybdotoxin and 10−6 M ryanodine. These results show that there are two components of mGlu responses in CA3 pyramidal neurons and thatImGlui andImGluo show different pharmacological properties.

Intracellular pH and metabolic activity of long-chain dicar☐ylic acid-producing yeast Candida tropicalis

The intracellular pH (pH i of α-ω-dicar☐ylic acid producing Candida tropicalis was determined by a fluorescence technique using the pH-sensitive fluorescent probe 5(6)-car☐yfluorescein diacetate. Fermentations with n-tridecane substrate to produce α,ω-tridecanedioic acid were carried out in a 5- l bioreactor in which growth and production were separated. During the growth phase, the measured pH i values were varied from 5.65 to 6.15 in all the experiments performed under different constant pH-operating conditions. The specific rates of growth, sucrose consumption, CO 2 production, and O 2 consumption were correlated with pH i. Cytochrome P450 monooxygenase (P450), which catalyzes n-alkane hydroxylation, was only slightly expressed during the growth phase. During the first 6 h of the production phase, P450 activity was induced rapidly accompanying higher pH i. A much higher level of P450 activity was observed at pH i of 6.55±0.15 for all the fermentations, with maximum productivity (1.919 g/l/h) occurring when using an optimal pH-control strategy. However, P450 activity, tridecanedioic acid productivity, and pH i decreased progressively during the latter part of the production phase, as a consequence of the metabolic activity changes of the cells. Even though culture pH has only a slight influence on pH i, the metabolic activity of C. tropicalis is sensitive to the variations in pH i. The measured pH i varied from 6.1 to 6.7 during the production phase for all the fermentations. Thus, both tridecanedioic acid productivity and P450 activity are correlated with pH i or pH gradients across the cell membrane.

Effect of phosphonate based corrosion inhibitors in a cooling water system

AbstractVarious corrosion inhibitors, including: 1-hydrox y ethylene-1,1 diphosphonic acid (HEDP), sodium molybdate, and zinc ions with various concentrations of chloride ion, were added to an aqueous corrosive medium, and the corrosion rate of the carbon steel was measured at various temperatures. It is shown that the corrosion rate is increased when the temperature or chloride ion concentration is enhanced, while if the concentration of HEDP or molybdate is increased, the corrosion rate is lowered. Furthermore, it is observed that in presence of more than 1200 ppm of the chloride ion and temperatures greater than or equal to 42·5°C the combination of HEDP, molybdate and zinc cannot control the corrosion in a cooling water system. Ultimately, a formulation consisting of HEDP, 2-phosphono butane-1, 2,4 tricarbox ylic acid, tolyltriazole, zinc, and polymeric compounds has been developed and tested in an industrial cooling water unit. Results have shown that the corrosion rate may be lowered to less than 25...

Synthesis and fluorescence properties of oregon green 514 labeled peptides

Oregon Green 514, with high photostability and a pKa of 4.8, is suitable for imaging applications. Labeling of peptide-bound resin with the car☐ylic acid form was optimized. Peptide conjugation resulted in altered fluorescence properties of the dye including a quenching of the intensity compared with that in aqueous buffers with a slight red-shift of the emission maximum.

Low-molecular weight car☐ylic acids in atmospheric aerosol at different European sites

Low-molecular weight car☐ylic acids in atmospheric aerosol at different European sites

Enzyme catalysed kinetic resolution of racemic 2,2-dimethyl-3-(2,2-disubstituted vinyl) cyclopropane car☐ylic acids anchored on polymer supports

Kinetic resolution of trans-substituted cyclopropane car☐ylic acids anchored on a solid support by lipase is described.

C3-fullero- tris-methanodicar☐ylic acid protects epithelial cells from radiation-induced anoikia by influencing cell adhesion ability

Anoikia is a type of apoptotic cell death that occurs in cells that are substrate-restricted in their growth. Buckminster-fullerenes represent a new class of chemical compounds with wide potential pharmacological antioxidant activity. In this report we provide the first demonstration that a water-soluble fullerene derivative, C 3-fullero- tris-methanodicar☐ylic acid, synthesized in our laboratories, is capable of inducing anoikia resistance in epithelial cells by a mechanism involving a ‘trophic’ effect on cell spreading-associated cytoskeletal components, i.e. on actin microfilaments.

A mild and efficient procedure for the preparation of acid chlorides from car☐ylic acids

Abstract Various car☐ylic acids are converted into the corresponding acid chlorides by treatment with trichloroacetonitrile and triphenylphosphine in methylene chloride at room temperature. Aryl acids show higher reactivity than alkyl acids under the conditions.

Enantiomerically pure 2-piperazinemethanols as novel chiral ligands of oxazaborolidine catalysts in enantioselective borane reductions

Abstract Novel enantiomerically pure 2-piperazinemethanols ( 3–5 ) were synthesized from 2-piperazinecar☐ylic acid 1 . The asymmetric reduction of aromatic ketones, ketimine and oxime ether has been performed with reagents prepared from 2-piprazinemethanol and borane to yield enantiomerically enriched alcohols and amines, respectively. The preferred absolute configuration of the product was dependent on the structure of the sulfonyl substituent in the chiral ligand.

Synthesis and characterization of 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride

Abstract 4-(4,6-Dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMTMM) was quantitatively synthesized by the coupling of 2-chloro-4,6-dimethoxy-1,3,5-triazine and N-methylmorpholine in THF, and fully characterized. Condensation of car☐ylic acids and amines by DMTMM proceeded effectively in THF to give the corresponding amides in good yield.

Cycloaddition reactions of sodium dinitroxytrioxide (Angeli's salt)

Abstract Angeli's salt undergoes a quantitative reaction with 1,3-diphenylisobenzofuran in a methanol/water solution at room temperature to give a product (1) explicable by an initial [4+2] cycloaddition reaction. Under the same conditions, Angeli's salt reacts with 1-naphthaldehyde to give 1-naphthoic acid in good yield. This reaction can also be explained by an initial [2+2] cycloaddition to give a hydroxamic acid, which is then hydrolyzed to the car☐ylic acid.

Use of 2-ethoxy-1-(ethoxycarbonyl)-1, 2-dihydroquinoline as a convenient reagent for the selective protection or derivatization of 2-hydroxycar☐ylic acids

EEDQ has been utilized as a convenient reagent for the selective protection of the hydroxy group of 2-hydroxycar☐ylic acids. In the presence of an appropriate amine nucleophile, EEDQ has also been utilized as a reagent for the derivatization of both of the hydroxy and car☐ylic acid group of 2-hydroxycar☐ylic acids. [Display omitted]

HMDS-promoted in situ amidation reactions of car☐ylic acids and amines

A number of N-acylalkylenediamines were synthesized in high yields by in situ monoamidation of car☐ylic acids with diamines. The amidation reactions were carried out simply by heating the substrates at 110 °C for 5–24 h in the presence of HMDS. HMDS-promoted in situ amidation reactions are generally applicable to the synthesis of N-acylalkylenediamines. [Display omitted]

A synthetic approach to the plakortones

The reaction of Grignard reagents with α-hydroxy-γ-ketocar☐ylic acids leads to the formation of tetrasubstituted γ-butyrolactones, one of which was converted into a bicyclic lactone 10 via consecutive bromoacetylation, Wittig cyclisation and hydrogenation. This represents an efficient methodology for the synthesis of the plakortones, 1–4. The reaction of Grignard reagents with α-hydroxy-γ-ketocar☐ylic acids leads to the formation of tetrasubstituted γ-butyrolactones, one of which was converted into a bicyclic lactone 10 via consecutive bromoacetylation, Wittig cyclisation and hydrogenation. This represents an efficient methodology for the synthesis of the plakortones, 1–4. [Display omitted]