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PubMed1991

Formation of cage-like particles by poly(amino acid)-based block copolymers in aqueous solution.

When dissolved in N,N-dimethylformamide and then dialyzed against phosphate-buffered saline, A-B-A block copolymers composed of poly [N5-(2-hydroxyethyl)-L-glutamine]-block-poly(gamma-benzyl-L-glutamate)- block-poly [N5-(2-hydroxyethyl)-L-glutamine] form particles. The particles are cage-like structures with average diameters of 300 nm (average polydispersity, 0.3-0.5). They are stable in aqueous solution at 4 degrees C for up to 3 weeks, at which time flocculation becomes apparent. Negative staining and freeze-fracture electron microscopy suggest that cage-like particles are formed by selective association of segregated micelle populations. A model of particle formation is presented in which B blocks form micelles in dimethylformamide. On dialysis against an aqueous solution, the extended A blocks then associate intermolecularly to form rod-shaped micelles, which connect the B block micelles. The result is a meshed cage-like particle. The implications of these observations on the aggregation behavior of polymeric surfactants in dilute solution are discussed.

Journal Article↗

PubMed1995

DT-diaphorase. Redox potential, steady-state, and rapid reaction studies.

NAD(P)H:quinone oxidoreductase (DT-diaphorse) appears to be a 2-electron transfer flavoprotein, which catalyzes the conversion of quinones into hydroquinones. Upon photoreduction in the presence of dimethylformamide, the enzyme forms a red semiquinone. In the absence of dimethylformamide, only 10% of the radical form is thermodynamically stabilized. This indicates a redox potential of the enzyme-bound semiquinone/reduced flavin couple that is higher than the midpoint potential for the oxidized flavin/semiquinone couple. The 2-electron redox potential was determined to be -159 +/- 3 mV at 25 degrees C, pH 7.0. In the presence of benzoquinone or 3-aminopyridine adenine dinucleotide phosphate, as NADPH analogue, there is no change in the redox properties of the enzyme flavin. A significant decrease is observed in the presence of the competitive inhibitor dicumarol (Em = -234 +/- 2 mV at pH 7.0). The reaction mechanism of the flavoprotein has been investigated by steady-state and stopped-flow kinetic methods using NADPH, NADH, deamino-NADPH, and 3-acetylpyridine adenine dinucleotide reduced form (APADH) as electron donors and K3Fe(CN)6, 4,5-dihydro-4,5-dioxo-1H-pyrrolo-[2,3-f]quinoline-2,7,9-tricarboxylic acid (PQQ), and 2,5-diaziridinyl-3,6-bis(carboethoxy-amino)-1,4-benzoquinone (AZQ) as electron acceptors in 50 mM phosphate buffer, pH 7.0, 25 degrees C. No evidence could be obtained to indicate that semiquinoid intermediates play a part in the catalytic mechanism of DT-diaphorase with quinones as acceptors. The rates of the reduction by NADPH, NADH, deamino-NADPH, and APADH (1.3 x 10(9), 8.8 x 10(8), 8.3 x 10(8) and 9.8 x 10(8) m-1 min-1, respectively) as well as the rates of the reoxidation by PQQ and AZQ (9 x 10(4) and 2.8 x 10(6) M-1 min-1, respectively) are directly proportional to substrate concentration, and there is no evidence of the formation of enzyme-substrate complexes. If such complexes do indeed exist, the affinity of the enzyme for substrate must be extremely low. Using K3Fe(CN)6 as electron acceptor, the rate of oxidation of fully reduced enzyme is 4.6 x 10(7) M-1 min-1 and it is accurately proportional to ferricyanide concentration. This rate represents that of flavin semiquinone formation, with the subsequent oxidation of the semiquinone being much faster, since no spectral evidence for semiquinone formation could be obtained. Studies were also conducted attempting to use apo-DT-diaphorase reconstituted with PQQ as coenzyme. The lack of activity toward AZQ, K3Fe(CN)6, and menadione suggests that DT-diaphorase can use PQQ only as electron acceptor and not as redox cofactor.

Flavin-Adenine Dinucleotide↗

PubMed1995

Enhanced transglycosylation activity of Arthrobacter protophormiae endo-beta-N-acetylglucosaminidase in media containing organic solvents.

The transglycosylation activity of endo-beta-N-acetylglucosaminidase from Arthrobacter protophormiae (endo-A) was enhanced by inclusion of organic solvents in the reaction mixture. In aqueous solution, the transglycosylation yield relative to starting substrate was 32% using Man9GlcNAc2Asn as donor and 0.5 M GlcNAc as acceptor. However, in the media containing 30% (v/v) acetone, dioxane, N,N-dimethylformamide, or dimethyl sulfoxide with 0.5 M GlcNAc as acceptor, the transglycosylation attained yields of 89, 13, 28, and 75%, respectively, as analyzed by high performance anion exchange chromatography. The enzyme was stable in media containing up to 30% acetone, 30% dimethyl sulfoxide, or 20% N,N-dimethylformamide at 37 degrees C for at least 30 min. The acceptor (GlcNAc) concentration must be greater than 0.2 M for efficient transglycosylation. Electrospray mass spectrometry analysis of the transglycosylation product obtained in 30% acetone with Man5GlcNAc2Asn as donor and methyl alpha-2-acetamido-2-deoxy-D-glucopyranoside as acceptor showed a mass ion of m/z 1249.4, consistent with the expected molecular weight. Analysis by 1H NMR of the product revealed that transglycosylation occurred at the C-4 of GlcNAc and the linkage was of the beta-configuration. In the acetone-containing medium, Glc, Man, 2-deoxy-Glc, and methyl alpha-D-GlcNAc can serve as a good acceptor as GlcNAc. Less favorable acceptors are xylose, fructose, 6-deoxy-Glc, and 3-O-methyl-D-glucose. On the other hand, GalNAc, Gal, allose, and 3-deoxy-Glc could not serve as acceptors of the enzyme transglycosylation.

Acetylglucosamine↗

PubMed2004

Comparison of the physical and chemical stability of niclosamide crystal forms in aqueous versus nonaqueous suspensions.

In an effort to produce physically stable and pharmaceutically acceptable suspensions of niclosamide, this study reports the differences in physical and chemical stability of aqueous vs. nonaqueous suspensions of a niclosamide anhydrate, two monohydrates HA and HB, a 1:1 niclosamide N,N-dimethylformamide solvate, a 1:1 niclosamide dimethyl sulfoxide solvate, a 1:1 niclosamide methanol solvate, and a 2:1 niclosamide tetraethylene glycol hemisolvate. Evaluation of aqueous and nonaqueous suspensions showed that in aqueous suspensions anhydrous, and solvated niclosamide crystal forms were transformed to a monohydrate, HA, which was reasonably stable but which did eventually transform to the most stable monohydrate HB. The order in which these crystal forms transformed to monohydrate HB were: Anhydrate > N,N-dimethylformamide > dimethyl sulfoxide > methanol > tetraethylene glycol > monohydrate HA. In a nonaqueous propylene glycol vehicle, the transformation to the monohydrous forms was not observed and on desolvation the solvated crystals transformed to the anhydrous form. In all cases, immediately upon desolvation or dehydration, the crystal structures of the desolvated materials were similar to that of the solvated materials. However, the isomorphic structures, formed after desolvation, were unstable and rehydrated or resolvated when exposed to the solvent or converted to the anhydrous form in a dry environment. The crystal forms remained chemically stable in both aqueous and nonaqueous suspensions for the length of the study.

Antinematodal Agents↗

PubMedDate not supplied

A method for the simultaneous determination of cocaine, benzoylecgonine, and ecgonine methyl ester in blood and urine using GC/EIMS with derivatization to produce high mass molecular ions.

A method for the simultaneous analysis of cocaine (COC), derivatized benzoylecgonine (BE), and derivatized ecgonine methyl ester (EME) has been developed. Blood or urine containing deuterated analogs of the three analytes is extracted by pouring over a Chem-Elut column and eluting with chloroform/isopropanol (9:1). The eluent is collected, split into two equal aliquots, and evaporated to dryness. In one aliquot, dimethylformamide and dimethylformamide dipropyl acetal are allowed to react and to derivatize BE to n-propyl COC. In the other aliquot, 4-fluorobenzoyl chloride, pyridine, and benzene are used to derivatize EME to p-fluoro-COC. COC is not affected by these reactions and may be found in either aliquot. Separation was performed on an HP 5890 GC using an HP-1 capillary column. The oven temperature was initially 100 degrees C for 1 minute, then programmed at 30 degrees/minute to a final temperature of 260 degrees C. The GC/MS was operated in the SIM mode, and the masses monitored were 303, 321, and 331 respectively for COC and derivatized EME and BE, and 308, 324, and 334 for the respective deuterated internal standards. The assay showed a minimum linear range of 0.05-2.0 mg/L for COC and 0.10-4.0 mg/L for each of the metabolites.

Cocaine↗

PubMed2006

Further quantification of the role of internal unstirred layers during the measurement of transport coefficients in giant internodes of Chara by a new stop-flow technique.

A new stop-flow technique was employed to quantify the impact of internal unstirred layers on the measurement of the solute permeability coefficient (P(s)) across the plasma membrane of internodes of the giant-celled alga Chara corallina using a cell pressure probe. During permeation experiments with rapidly permeating solutes (acetone, 2-propanol, and dimethylformamide), the solute concentration inside the cell was estimated and the external medium was adjusted to stop solute transport across the membrane, after which responses in turgor were measured. This allowed estimation of the solute concentration right at the membrane. Stop-flow experiments were also simulated with a computer. Both the stop-flow experiments and simulations provided quantitative data about internal concentration gradients and the contribution of unstirred layers to overall measured values of P(meas)(s) for the three solutes. The stop-flow experimental results agreed with stop-flow simulations assuming that solutes diffused into a completely stagnant cell interior. The effects of internal unstirred layers on the underestimation of membrane P(s) declined with decreasing P(s). They were no bigger than 37% in the presence of the most rapidly permeating solute, acetone (P(meas)(s) =4.2 x 10(-6) m s(-1)), and 14% for the less rapidly permeating dimethylformamide (P(meas)(s) =1.6x10(-6) m s(-1)). It is concluded that, even in the case of rapidly permeating solutes such as isotopic water and, even when making pessimistic assumptions about the internal mixing of solutes, an upper limit for the underestimation of P(s) due to internal unstirred layers was 37%. The data are discussed in terms of recent theoretical estimates of the effect of internal unstirred layers and in terms of some recent criticism of cell pressure probe measurements of water and solute transport coefficients. The current stop-flow data are in line with earlier estimations of the role of unstirred layers in the literature on cell water relations.

Biological Transport↗

PubMed2000

A complex containing both five- and six-coordinate

The title compound, aquachloro4,4'-dibromo-2, 2'-[o-phenylenebis(nitrilomethylidyne)]diphenolato-O,N,N', O'iron(III)-chloro4,4'-dibromo-2, 2'-[o-phenylenebis(nitrilomethyli-dyne)]diphenolato-O,N,N', O'iron(III)-dimethylformamide (1/1/1), [FeCl(C(20)H(12)Br(2)N(2)O(2))][FeCl(C(20)H(12)Br(2)N(2)O(2))(H(2)O)] .C(3)H(7)NO, contains one independent five-coordinate [FeCl(C(20)H(12)Br(2)N(2)O(2))] monomer, one six-coordinate [FeCl(C(20)H(12)Br(2)N(2)O(2))(H(2)O)] monomer and a non-coordinating dimethylformamide solvent molecule in the asymmetric unit. In the five-coordinate monomer, the Fe atom shows distorted square-pyramidal geometry, with the N and O atoms of the ligand at the base and the Cl atom at the apex of the pyramid. In the six-coordinate monomer, the Fe atom is in a distorted octahedral geometry and coordinated by the donor atoms of the tetrafunctional ligand in the horizontal plane, and the coordination sphere is completed by the O atom of the water molecule and the Cl atom at the axial positions. The title compound contains intermolecular O-H.O hydrogen bonds. Apart from these hydrogen bonds, there are also intermolecular C-H.Cl and C-H.O contacts.

Journal Article↗

PubMed2004

Crystal structure of the supramolecular linear polymer formed by the self-assembly of mono-6-deoxy-6-adamantylamide-beta-cyclodextrin.

Mono-6-deoxy-6-adamantylamide-beta-cyclodextrin-dimethylformamide-15H2O, C53H85NO35.C3H7NO.15H2O, crystallizes in the orthorhombic space group P2(1)2(1)2(1). The adamantyl group is inserted into the cyclodextrin cavity of the adjacent molecule, entering by the side of the secondary hydroxy rim, thus forming a supramolecular linear polymer by self-assembly. Adjacent macrocycles are linked into columns by hydrogen bonds involving the nearest glucose residues, and the structure is further stabilized by their involvement in hydrogen bonding with water molecules which reside in channels surrounding the polymer columns, thus acting as bridges between the cyclodextrin units. The centroid of the adamantyl group lies below the plane formed by the seven glycosidic O atoms of the host cyclodextrin, excluding water molecules from the secondary side of beta-cyclodextrin (beta-CD). Between the adamantyl group and the primary hydroxy rim of the cyclodextrin cavity lies a dimethylformamide molecule, which shields the hydrophobic adamantyl group from the primary hydroxy rim of its carrying beta-CD and excludes water molecules from the primary side of the beta-CD cavity.

Amantadine↗

PubMed1987

Mild, orthogonal solid-phase peptide synthesis: use of N alpha-dithiasuccinoyl (Dts) amino acids and N-(iso-propyldithio)carbonylproline, together with p-alkoxybenzyl ester anchoring linkages.

Several N alpha-dithiasuccinoyl (Dts) amino acids (1) have been esterified without racemization by use of either N,N'-dicyclohexylcarbodiimide or 1-(3-dimethylamino-propyl)-3-ethylcarbodiimide hydrochloride, each in the presence of 4-dimethylaminopyridine (0.1 equiv.), to 2, 4, 5-trichlorophenyl 4'-hydroxymethylphenoxyacetate (10) or the corresponding propionate (11). The resultant handle derivatives (8,9) were purified and then quantitatively attached onto aminomethyl supports by couplings using as solvent N,N-dimethylformamide containing 1-hydroxybenzotriazole (0.1 M). This methodology facilitates anchoring of Dts-amino acids as p-alkoxybenzyl esters, which can be cleaved in good yields by trifluoroacetic acid-dichloromethane (1:1) at 25 degrees. Model experiments established that quantitative thiolytic removal (greater than 99.8%) of the Dts group occurs with (i) beta-mercaptoethanol (0.5 M)-N,N-diisopropylethylamine (0.5 M) in dichloromethane, 2 X 2 min; (ii) N-methylmercaptoacetamide (0.5 M)-N-methylmorpholine (0.5 M) in dichloromethane, 2 X 2 min; and (iii) N-methylmercaptoacetamide (0.5 M)-1-hydroxybenzotriazole (0.1 M) in N,N-dimethylformamide, 2 X 2 min. The susceptibility of the Dts functionality to nucleophiles was also defined, including demonstration of tertiary amine-catalyzed hydantoin formation from Dts-dipeptidyl units, but side reactions from these processes are entirely avoided under appropriate conditions relevant to peptide synthesis. These observations were exploited to devise efficient, racemization-free solid-phase syntheses of a number of model peptides in high yields and purities, including L-leucyl-L-alanylglycyl-L-valine, H-Gly6-Val-OH, H-Met-Ala-Gly-OH, methionine-enkephalin, and bradykinin.

Amino Acids↗

PubMed1990

Large fragments of nef-protein and gp110 envelope glycoprotein from HIV-1. Synthesis, CD analysis and immunoreactivity.

Chemical synthesis of large peptide fragments (from 18 to 66 amino acid residues long) of the gp110 envelope glycoprotein and of nef-protein from HIV-1 was achieved by the solid phase method. Stepwise assembling of the peptide chains was carried out automatically on 4-(oxymethyl)-phenylacetamidomethyl resin using the N-alpha-butyloxycarbonyl amino acids with benzyl-based side chain protecting groups. Two elongation protocols were used depending on the peptide chain length: a standard cycle, mainly characterized by a single coupling step (Boc-amino acid symmetrical anhydride in dimethylformamide), and an optimized one for large peptides, based on a double coupling strategy (Boc-amino acid symmetrical anhydride first in dimethylformamide, then in dichloromethane). Final cleavage of the peptide from the solid support was carried out by anhydrous hydrogen fluoride and crude peptides were purified by C18 reverse phase medium pressure liquid chromatography after molecular filtration. Characterization of the purified peptides was done by analytical HPLC, amino acid content determination, and circular dichroism analysis both in polar (H2O) and in non-polar (TFE) environments. Immunoreactivity of anti-nef positive sera from HIV-1 infected patients by ELISA with the synthetic peptides was investigated. The results showed four major antigenic regions of nef-protein and mainly the immunodominance of the N- and C-termini of the molecule. Several of these peptides should prove to be useful for both diagnosis and vaccination purposes.

Amino Acid Sequence↗

PubMed1968

Reaction of nitrosoguanidine (N-methyl-N'-nitro-N-nitrosoguanidine) with tobacco mosaic virus and its RNA.

"Nitrosoguanidine" (N-methyl-N'-nitro-N-nitrosoguanidine) acts on polynucleotides in neutral aqueous solution, methylating guanine in the 7-position, and, to a much lesser extent, adenine. In 67 percent dimethylformamide the effect on the purines decreased, and what seems to be 3-methyl-cytosine appeared. In formamide solution no base changes were detected. Nitrosoguanidine had little mutagenic effect on tobacco mosaic virus RNA in water; it had greater effect in dimethylformamide, and even greater in formamide; it was a strong mutagen only when it acted on intact tobacco mosaic virus particles. Thus, neither the methylation of guanine nor the cytosine modification represents the main mutagenic event.

Adenine↗

PubMed1979

Plasma levels of vitellogenin in Chrysemys picta during the annual gonadal cycle: measurement by specific radioimmunoassay.

A RIA for turtle (Chrysemys picta) vitellogenin is described. After dimethylformamide precipitation of vitellogenin from the plasma of estrogen-treated female turtles, antibodies were developed in rabbits. The dimethylformamide precipitate was further purified by o-triethylaminoethyl cellulose column chromatography; the vitellogenin component eluted as a single peak. This material was used for iodination by a mild chloramine method. Antibodies to turtle vitellogenin did not cross-react with plasma from male turtles or vitellogenic females of other vertebrate groups, including lizards and snakes. Limited cross-reactivity exists among the chelonians, however. Using a 1:5000 dilution of antiserum, the limit of detection was 15 ng, and the midrange was 320 +/- 45 ng. For an antiserum dilution of 1:1000, these figures were 30 and 600 +/- 37 ng, respectively. Using this assay, the seasonal pattern of plasma vitellogenin in the turtle has been described, and preliminary studies on in vitro hepatic vitellogenesis have been performed.

Animals↗

PubMed1982

Effects of organic solvents on flagellar asymmetry and quiescence in sea urchin sperm.

Low concentrations of methanol, 2-propanol and ethylene glycol increase the asymmetry of the flagellar waveforms ad the turning rate of both live sperm and potentially symmetrical sperm reactivated with 1 mM-MgATP2-, while at the same time causing a decrease in the heat frequency. Similar effects are observed if the solvents are added to preparations of potentially symmetrical sperm reactivated in the presence of 1 mM free Ca2+, or to potentially asymmetrical sperm reactivated without added Ca2+, A second group of solvents, N,N-dimethylformamide, formamide and p-dioxane, also decrease the flagellar beat frequency, but have the opposite effect on symmetry, reducing the asymmetry of the waveforms and the turning rate of potentially symmetrical sperm reactivated in the presence of 1 mM free Ca2+. These effects of solvents are all reversible within about 5 min after initial exposure to solvent. Higher concentrations of methanol and 2-propanol (above approximately 5 and 0.8 mole %, respectively) induce quiescence in potentially asymmetrical sperm reactivated with concentrations of MgATP2- ranging from 10 microM to 1 mM. The quiescent flagella initially assume a bent form very similar to that seen in Ca2+-induced quiescence, and show a subsequent time-dependent distortion of the initial bent from with eventual disintegration and splitting off of bundles of microtubules. Dimethylformamide, formamide and dioxane have almost no effect on the intrinsic asymmetry of potentially asymmetrical sperm reactivated in the absence of added Ca2+, but addition of these solvents to potentially asymmetrical sperm that have been induced to become quiescent by addition of 0.1 mM free Ca2+ causes the sperm to resume swimming with flagellar waveforms that are substantially more symmetrical that those of the starting preparation before the addition of Ca2+. Mild digestion with trypsin of reactivated sperm that have been induced either to beat asymmetrically or to become quiescent by addition of methanol causes a gradual appearance of symmetrical flagellar beating, as in the case of Ca2+-induced quiescence. The flagellar beat frequency, however, remains low, at about 20 Hz. The results suggest that the solvents either mimic or block the action of CA2+ by interaction with a Ca2+-dependent regulatory protein, and may also induce alteration in the rate constants of dynein ATPase.

1-Propanol↗

PubMed1980

Human proinsulin, VII: synthesis of two protected peptides corresponding to the sequences 1--45 and 46--96 of the prohormone.

The synthesis of two protected large peptides 1--45, and 46--86 covering the entire amino acid sequence of human proinsulin is described. Peptide 1--45, was synthesized from two intermediate fragments 1--23 and 24--45 and purified by countercurrent distribution in dimethylformamide system (K = 0.5). Peptide 46--86 was synthesized from two intermediate fragments 46--70 and 71--86 and purified by countercurrent distribution in two solvent systems, the dimethylformamide system (K = 0.06), and the toluene system (K = 0.16).

Amino Acid Sequence↗

PubMed1983

Physiochemical studies on indocyanine green: molar lineic absorbance, pH tolerance, activation energy and rate of decay in various solvents.

Physiochemical studies were carried out on the tricarbocyanine dye indocyanine green in biological fluids and organic solvents. The molar lineic absorbance epsilon of the compound was highest in organic solvents (methanol, 1.2-propanediol, dimethylformamide) and bile, but lowest in water and duodenal fluid. Indocyanine green remained stable in methanol and bile (t1/2 greater than 1 year) but was rapidly decomposed to a colourless derivative in duodenal fluid and distilled water (t1/2 3.6 days and 1.4 days, respectively). It was thermostable (120 degrees C) in methanol and 1.2-propanediol but thermolabile in water and dimethylformamide where the activation energy for the decomposition reaction was low. At ambient temperature (20 degrees C) indocyanine green was particularly labile at pH less than 5 and pH greater than 11. The rate of decay of indocyanine green in various solvents indicated that the rate limiting step in the decay process was either a first or zero order reaction.

Chemical Phenomena↗

PubMed1980

Cryoprotective effects of some amides on rabbit spermatozoa.

Semen was diluted 1:9 with egg yolk-citrate medium containing 0.31--3.1 M (final concentration) formamide, butyramide, acetamide, propionamide, dimethylformamide, lactamide, malomide, ethylene glycol, trimethylene glycol, dimethylsulphoxide (DMSO) or glycerol. After 30 min incubation at 20 degrees C, sperm motility was superior in hypertonic solutions of acetamide, lactamide, dimethylsulphoxide, trimethylene glycol and ethylene glycol. Some of these compounds were added to semen diluted 1:2 in an isotonic egg-yolk-glucose-lactose-raffinose solution and frozen by the pellet method. Relatively good survival of motility was obtained in 1.0 M-DMSO, -lactamide or -acetamide. Dimethylformamide (0.5 M), ethylene glycol (0.5--1.5 M), trimethylene glycol (1.5 M) and propionamide (0.75 M) also gave some protection. Insemination of does with semen frozen and thawed with 1.0 M-DMSO, -lactamide or acetamide gave fertilization rates of 68--88%, and 84% (38/45) of does gave birth to an average of 5.3 young.

Amides↗

PubMed1986

Critical evaluation of 7-ethoxycoumarin O-deethylase activity measurement in intact isolated rat hepatocytes.

In the determination of 7-ethoxycoumarin O-deethylase activity in intact isolated rat hepatocytes various factors influence the assay, including: the decay of 7-ethoxycoumarin fluorescence which is temperature and pH dependent; the measured fluorescence which has to be adjusted for the inner filter effect; glucose addition to the medium which influences the activity; all organic solvents which inhibit the enzymic activity, with dimethylformamide provoking the smallest effect (partial competitive inhibition); the enzymic reaction which is inhibited by the product of reaction; and the presence of bovine serum albumin in the medium which affects the enzymic activity. Biphasic kinetics are observed for the O-deethylation of ethoxycoumarin in intact isolated rat hepatocytes. For the high-affinity component, Km and Vmax values are 5 microM and 43 pmol/min X 10(6) cells and for the low-affinity component are 414 microM and 915 pmol/min X 10(6) cells. Addition of the substrate in dimethylformamide or omitting bovine serum albumin from the medium cause important changes in these kinetic parameters.

7-Alkoxycoumarin O-Dealkylase↗

PubMed1980

On-column gas chromatographic synthesis of 1,3-dialkyl (c = 1-10), benzyl, and cyclohexyl barbiturate derivatives.

Procedures are described for the on-column gas chromatographic synthesis of various N-alkyl-N-alkyl barbiturates where groups added to the nitrogens are benzyl, cyclohexyl, or straight chains with 1 to 10 carbons. The 1,3-dialkyl barbiturates having methyl, ethyl, n-propyl, n-butyl, cyclohexyl, isopropyl, or t-butyl groups can be prepared on-column by injecting an aliquot of a chloroform solution of the barbiturate with the appropriate N,N-dimethylformamide dialkyl acetal. The 1,3-dialkyl barbiturates where benzyl or butyl through decyl groups are added can be similarly prepared with N,N-dimethylformamide dineopentyl acetal and the appropriate alcohol to yield the desired compound. The 1-alkyl (I)-3-alkyl-(II) barbiturates where the alkyl groups differ are prepared by on-column reaction reaction of a barbiturate with aliquots of each of the respective reagents giving the desired groups.

Alkylation↗