Ortho-substituted Derivatives Research Articles

η6-Tricarbonylchromium Complexes of Methyl 4,6-O-Benzylidene-α-D-glucopyranosides

The structures of the η6-tricarbonylchromium complexes of four methyl 4,6-O-benzylidene-α-glucopyranosides, (2)–(5), have been determined, as well as that of the free monosaccharide, (1). These compounds are (R)-methyl 2,3-di-O-methyl-4,6-O-benzylidene-α-d-glucopyranoside [(1), C16H22O6], tricarbonyl{(R)-methyl 2,3-di-O-methyl-4,6-O-(η6-benzylidene)- α-d-glucopyranoside}chromium(0) {(2), [Cr(C16H22O6)(CO)3]}, tricarbonyl{(R)-methyl 2,3-di-O-methyl-4,6-O-[(1R,2S)-2-methylthio-η6– phenylmethylene]-α-d-glucopyranoside}chromium(0) {(3), [Cr(C17H24O6S)(CO)3]}, tricarbonyl{(R)-methyl 2,3-di-O-methyl-4,6-O-[(1R,2S)-2-diphenylphosphino-η6-phenylmethylene]-α-d-glucopyranoside}chromium(0) dichloromethane solvate {(4), [Cr(C28H31O6P)(CO)3].CH2Cl2} and tricarbonyl[(R)-methyl 2,3-di-O-methyl-4,6-O-(4-methoxy-η6-phenylmethylene)-α-d-glucopyranoside]chromium(0) {(5), [Cr(C17H24O7)(CO)3]}. These structural studies were undertaken to establish the solid-state conformation of the complexed arene ring in the 4,6-O-benzylidene and the 4,6-O-p-methoxyphenylmethylene η6-Cr(CO)3 complexes, and also the absolute stereochemistry of some ortho-substituted derivatives of the 4,6-O-benzylidene complex.

The Synergic Extraction of Rare Earth Metals with ortho-Substituted 1-Phenyl-3-methyl-4-aroyl-5-pyrazolones and Trioctylphosphine Oxide.

The synergic extractions of rare earth metals (scandium, lanthanum and lutetium, M3+) with ortho- substituted 4-aroyl derivatives of 1-phenyl-3-methyl-5-pyrazolone (HA) and a neutral ligand, trioctylphosphine oxide (TOPO, L) in benzene were studied. Eight ortho-substituted 4-aroyl derivatives of pyrazolone have been prepared. Linear relationships between the extraction constants and the acid dissociation constants of aroylpyrazolones were obtained when TOPO was not added. The metal chelates of aroylpyrazolones react with TOPO to form MA3L and MA3L2 types of adducts in the synergic extractions. Obvious steric hindrances of the terminal substituents at ortho- position of 4-aroyl group of the ligands on the adduct formation reaction were observed by the comparison of adduct formation constants.

Patent Evaluation Pulmonary-Allergy, Dermatological, Gastrointestinal & Arthritis: Novel prostaglandin synthase inhibitors

This patent application from DuPont Merck discloses ortho-substituted biphenylsulfonyl derivatives, which are claimed to be selective prostaglandin (PG) G/H synthase-2 (cyclooxygenase-2; Cox-2) inhibitors and thus, have utility as anti-inflammatory, analgesic and antipyretic agents.

Pressure—temperature-induced conductivity in polyaniline base and salts

The conductivities of polyaniline (and poly(2-methoxyaniline), poly(2-methylaniline)) and of the sulfonated derivative have been studied as a function of pressure (0 to 30 kbar) and of temperature (20 to 100–400 °C). Conductivity measurements were made with the aid of impedance spectroscopy in a piston—cylinder high-pressure cell. The conductivity of emeraldine chloride is quite stable up to 10 kbar and then increases continuously up to a factor 50 (1 to 60 S cm −1 at 100 °C, 25 kbar). Similar behaviour is observed for the ortho-substituted derivatives (poly(2-methylaniline) and poly(2-methoxyaniline)) as well as for the self-doped sulfonated polyaniline. The conductivity increases regularly with temperature and then drops irreversibly: highest values are observed at 90, 70 and 60 °C for the self-doped material and the chlorides, poly(2-methoxyaniline chloride) and poly(2-methylaniline chloride), respectively. A strong increasing in conductivity is observed versus temperature and pressure, up to 10 −4 S cm −1, at 300 °C under 20 kbar for the emeraldine base. The nature of the charge carriers (electrons or protons) is discussed.

Inhibition of corrosion of aluminium pigments byortho-substituted phenol and aniline derivatives

Aluminium pigments are found to corrode with the evolution of hydrogen when in contact with water-butyl glycol mixtures at pH 10. Stability tests showed that the corrosion reaction can be inhibited by the addition of chelate forming ortho-substituted phenol derivatives, and that ortho-substituted aniline derivatives are ineffective corrosion inhibitors. The results can be explained in terms of Pearson's principle of hard and soft acids and bases. The measurement of the evolution of hydrogen was used to study relative differences in behaviour between ortho-substituted phenol derivatives. It is concluded that the most effective corrosion inhibitor is salicyl alcohol.

Inhibition of corrosion of aluminium pigments by <I>ortho</I>-substituted phenol and aniline derivatives

Aluminium pigments are found to corrode with the evolution of hydrogen when in contact with water-butyl glycol mixtures at pH 10. Stability tests showed that the corrosion reaction can be inhibited by the addition of chelate forming ortho-substituted phenol derivatives, and that ortho-substituted aniline derivatives are ineffective corrosion inhibitors. The results can be explained in terms of Pearson's principle of hard and soft acids and bases. The measurement of the evolution of hydrogen was used to study relative differences in behaviour between ortho-substituted phenol derivatives. It is'concluded that the most effective corrosion inhibitor is salicyl alcohol.

Direct and enantiospecific ortho-benzylation of phenols by the Mitsunobu reaction

ortho-Substituted phenol derivatives with high optical purity have been obtained directly by Mitsunobu reaction between an appropriate phenol and an optically active benzyl alcohol. In this reaction, the chemical yield was well balanced with the optical purity of the ortho-substituted compound when 5 equiv. of phenol was allowed to react with 1 equiv. of alcohol in a solvent such as dichloroethane or toluene. In addition, it was confirmed by an X-ray analysis of the product that stereochemical inversion of the asymmetric centre took place in this reaction, as well as the usual Mitsunobu reaction. This reaction is useful in the preparation of optically active phenol derivatives possessing a diarylmethane moiety.

Nonselective and Efficient Fluorescent Labeling of Glycans Using 2-Amino Benzamide and Anthranilic Acid

Reaction conditions for conjugation of two fluorescent ortho-substituted aniline derivatives, 2-amino benzamide (2-AB) and 2-anthranilic acid (2-AA), to N- and O-glycans have been investigated. Conjugation conditions for attaching 2-AB and 2-AA to core-fucosylated and nonfucosylated glycans were developed using complex N-glycans radiolabeled at the nonreducing terminus with [ 3H]C6-galactose. Optimal conditions for each of the following reaction parameters were experimentally defined: [glycans], [2-AB] or [2-AA], solvent and acid composition, temperature and time of Schiff′s base formation, nature of reductant, and temperature and time of reduction. Using the optimized reaction conditions it has been shown with several standard glycans and glycoprotein-derived glycan libraries that (i) molar labeling efficiencies are high and essentially independent of the amount of glycans; (ii) negligible (< 2 mol %) desialylation occurs during conjugation; (iii) glycan labeling is nonselective, i.e., independent of glycan structure; and (iv) insignificant fluorescent or chemical "blank" is recovered during the glycan-labeling and purification protocol. Labeling glycan pools with 2-AB or 2-AA therefore allows representative glycan profiles to be obtained and also allows relative molar quantitation of individual glycans in a pool. The 2-AB label is compatible with several chromatographic means for separation of carbohydrates including Bio Gel P4 gel permeation, high-performance anion-exchange chromatography with fluorescence detection, and a variety of HPLC procedures, as well as with mass spectrometric methods including matrix-assisted laser desorption-mass spectrometry and electrospray-mass spectrometry. The 2-AA label is particularly well-suited for electrophoretic separations by polyacrylamide gel electrophoresis. These fluorophores show high intrinsic sensitivity and thus facilitate very sensitive analysis of protein glycosylation.

Conjugated Ionic Polyacetylenes. 9. Polymerization of N-methyl-2-ethynylpyridinium Trifluoromethanesulfonate in Aprotic Polar Solvents

Ionic polymerization of the acetylene bond in N-methyl-2-ethynylpyridinium trifluoromethanesulfonate (triflate) monomer (HMTf) was investigated at room temperature in aprotic polar solvents such as acetonitrile, DMF, and DMSO. Polymerization was initiated by pyridine and pyridine derivatives and the resulting reactions were monitored by IR, UV-visible, and NMR spectroscopy. Polymerization of HMTf in aprotic polar solvents resulted in incomplete conversions. Conversions were strongly affected by the [monomer]/[initiator] ratio. Reaction rates when initiated with pyridine were not influenced by the polarity of the solvent at the same monomer concentration. Reactivity of initiators decreased in the order alkyl > alkenyl > alkynyl substitution. Ortho-substituted pyridine derivatives were found to be less reactive than the para derivatives. There was no substantial difference with respect to reaction rates and conversions of polymerizations when substituted pyridines were used or the pyridine molecules were linked by ethane, ethylene, or acetylene units. Polymerization of N-methyl-2-ethynylpyridinium triflate proceeds according to a complex zwitterionic/anionic mechanism. Two different kinds of chain growth were found and a general reaction scheme was proposed to account for the experimental findings.

Enantioseparation on Fluoro-Methylphenylcarbamates of Cellulose and Amylose as Chiral Stationary Phases for High-Performance Liquid Chromatography

Six phenylcarbamate derivatives of cellulose and amylose having both an electron-withdrawing fluoro group and an electron-donating methyl group on the phenyl moieties were synthesized, and their chiral recognition abilities were evaluated as chiral stationary phases for high-performance liquid chromatography. The resolving abilities were compared with those of chloro-methylphenylcarbamate derivatives of cellulose and amylose. The chiral recognition abilities of fluoro-methylphenylcarbamates of cellulose and amylose were dependent on the position of the substituents. The cellulose derivatives with fluoro and methyl groups at the meta and para positions showed higher resolving power than the ortho- and meta-disubstituted derivative as observed for the chloro-methylphenylcarbamate derivatives of cellulose. On the other hand, the ortho-substituted derivative of amylose, tris(5-fluoro-2-methylphenylcarbamate), showed high chiral recognition as well as the meta- and para-disubstituted derivatives. The different chiral recognition was discussed on the basis of IR and CD spectroscopic data.

Dimethyl-, dichloro- and chloromethylphenylcarbamates of amylose as chiral stationary phases for high-performance liquid chromatography

Twelve dimethyl-, dichloro- and chloromethylphenylcarbamate derivatives of amylose were prepared and their chiral recognition abilities were evaluated as chiral stationary phases for high-performance liquid chromatography. ortho-Substituted phenylcarbamate derivatives of amylose showed high chiral recognition abilities, although cellulose phenylcarbamate derivatives with ortho substituents on the phenyl moiety showed low chiral recognition. The superiority of 5-chloro-2-methylphenylcarbamate over the corresponding dimethyl- and dichlorophenylcarbamate derivatives of amylose was demonstrated. The roles of the NH residue of the carbamate moieties and methyl and chloro groups in chiral recognition were elucidated using IR and 1H NMR spectroscopic data. The tris(5-chloro-2-methylphenylcarbamate) of amylose exhibited the highest chiral recognition ability among the amylose derivatives synthesized, and can be used for the separation of some chiral drug enantiomers.

Rotational isomerism of disubstituted benzenes in the alkylphenyldi(1-adamantyl)methanol series

Addition of di(1-adamantyl) ketone to the appropriate tolyllithium compounds gives all five positional and rotational isomers of tolyldi(1-adamantyl)methanol, as evidenced by 1H and 13C NMR spectroscopy. Synthesis of the ortho-substituted derivatives gives essentially the anti isomer (anti/syn= 11.6), the meta-derivatives mainly syn(anti/syn= 0.77). Thermal equilibration converts anti,ortho almost exclusively to syn,ortho while the anti/syn ratio is virtually unchanged for the meta derivatives. The rotation barriers for the ortho- and meta-derivatives are 39 and 27 kcal mol–1, respectively. The anti/syn ratio for the synthesis of the corresponding meta-(tert-butyl)-substituted alcohols increases with the reaction time. Thermal equilibration indicates that the anti isomer is about 0.3 kcal mol–1 more stable than the syn, due to attractive interactions between the tert-butyl group and the adamantyls, whereas the syn,meta-tolyl is 0.2 kcal mol–1 the more stable. Molecular mechanics calculations slightly exaggerate the stability of the anti rotamers. Butyllithium-catalysed rotation of the meta-substituted alcohols favours the anti-isomers in both cases, much more for But than for Me. When the meta-substituted alcohols are converted to the corresponding methanes by the (COBr)2–Bu3SnH procedure, rotamerically mixed products are obtained. Again the syn,meta-tolyl and the anti,meta-(tert-butyl)phenyl derivatives are the more stable, by about 0.15 kcal mol–1 in both cases. Reaction of anti,ortho-tolyldiadamantylmethanol gives a single methane, the syn rotamer. The rotation barrier for the meta-tolyldiadamantylmethanes is less than 1 kcal mol–1 greater than that for the corresponding alcohol. The mechanism of organolithium addition to ketones is discussed.

Heteroatom-directed metalation. Lithiation of N-propenylbenzamides and N-propenyl-o-toluamides. Novel routes to ortho-substituted primary benzamide derivatives and N-unsubstituted isoquinolin-1(2H)-ones

Reaction of N-propenylbenzamides 4 and 9, obtained by LDA-induced isomerization of the corresponding N-allylbenzamides 1, 8, and 14, with 2 equiv of sec-butyllithium or tert-butyllithium at low temperature regiospecifically generates the highly reactive N,ortho-dilithiated species (e.g., 5 and 17). These dilithio species react avidly with a wide spectrum of electrophilic reagents, including alkyl halides, giving adducts which on hydrolysis with warm 50% aqueous acetic acid are converted into ortho-substituted primary benzamides in excellent yields

Crystal structure of diaryl sulphur diimides Ortho-substituted derivatives

Crystal structure of diaryl sulphur diimides Ortho-substituted derivatives

Comparative mechanistic study of the reactions of benzophenone with n-butylmagnesium bromide and n-butyllithium

Substituent effects on reactivity and product distribution (addition vs reduction) were determined for the reactions of benzophenones with n-BuMgBr and n-BuLi at 0 o C. In case of the reaction with n-BuMgBr, meta and para-substituted benzophenones gave a reasonably linear Hammett plot, from which the ρ value of 1.45 was calculated, while ortho-substituted derivatives deviated downward from the correlation line. In contrast, the reaction with n-BuLi exhibited very small substituent effects on reactivity. The product distribution is highly dependent on substitutents in the n-BuMgBr reaction, whereas it is essentially independent of substituents in the n-BuLi reaction. Mechanistic differences between the reactions of these two reagents are discussed on the basis of these experimental results

Crystal structure of diaryl sulphur diimides Ortho-substituted derivatives

Crystal structure of diaryl sulphur diimides Ortho-substituted derivatives

Steric effect of ortho-substituents of 1-phenyl-3-methyl-4-aroyl-5-pyrazolones on the synergic extraction of lutetium with trioctylphosphine oxide

The substituent effect of ortho-substituted 4-aroyl derivatives of 1-phenyl-3-methyl-5-pyrazolones (HA) on the adduct formation reaction between their lutetium chelates and a neutral ligand, trioctylphosphine oxide (TOPO, L), in benzene was studied using a liquid-liquid extraction system. The lutetium 4-aroyl-5-pyrazolonates react with TOPO to form LuA 3L and LuA 3L 2 types of adducts. An obvious steric hindrance of the terminal group on the adduct formation reaction was observed. Linear relationships between the acid dissociation constant of the ortho-substituted 4-aroyl-5-pyrazolone derivatives and those of the corresponding benzoic acids, between the extraction constants of lutetium and the acid dissociation constants of pyrazolones and between the adduct formation constants of TOPO and the acid dissociation constants of pyrazolones could be obtained.

Kinetic resolution of (η 6-arene)chromium complexes by a lipase

Tricarbonylchromium complexes of ortho-substituted benzyl alcohol derivatives were kinetically resolved by asymmetric esterification with a lipase.

Study of intramolecular hydrogen bond in ortho-substituted derivatives of tetrafluoroaniline according to IR absorption spectra

Study of intramolecular hydrogen bond in ortho-substituted derivatives of tetrafluoroaniline according to IR absorption spectra

Quantitative Struktur-Aktivitäts-Beziehungen für die Wachstumshemmung von autotrophen Chlorella vulgaris-Suspensionen durch substituierte Aniline and Anilinhydrochloride

Summary The influence of 30 substituted aniline derivatives on the autotrophic growth of Chlorella vulgaris suspensions was investigated. Isoactive concentrations inhibiting the growth by 50% vary from 4.5 - 10-3 to 4.5 - 10-5 M within the studied group of substances. Isoactive inhibitory values of pc5o were determined from dosage-effectivity relations and used as activity parameters for structure-activity correlations. Simple regressions equations are reported, discussed and compared with analogous QSAR of earlier tested series. Displays of the pc5o values as function of various series of hydrophobic substituent constants showed linear relations with high correlation coefficients contrary to electronic substituent parameters. Ortho-substituted derivatives were less active and gave functions. With exception of NH2-, C02H-, N02- and OH-substituted aniline derivatives could be calculated a simple QSAR for the autotrophic growth inhibition of Chlorella vulgaris suspensions.