Showing papers on "Alkylation published in 1978"

Supported liquid-phase catalysts

Abstract: A discussion of catalysis by supported catalysts that are liquid at reaction temperature covers the preparation, composition, and structure of copper chloride-based Deacon catalysts used, e.g., for the oxychlorination of ethylene; alkali-promoted vanadium catalysts for sulfur dioxide oxidation in sulfuric acid manufacturing; kieselguhr-supported phosphoric acid used in the oligomerization of alkenes and alkylation of aromatics for gasoline and polymer production and in the hydration of alkenes to alcohols; and theoretical aspects of supported liquid catalysts, including mechanism of adsorption and models of the distribution of the liquid on the support, the effects of diffusion and loading on the reaction kinetics, effective diffusion coefficients; and diffusion and reaction in the liquid phase.

Alkylation of deoxyribonucleic acid by carcinogens dimethyl sulphate, ethyl methanesulphonate, N-ethyl-N-nitrosourea and N-methyl-N-nitrosourea. Relative reactivity of the phosphodiester site thymidylyl(3'-5')thymidine.

Abstract: 1. The ethyl phosphotriester of thymidylyl(3′-5′)thymidine, dTp(Et)dT, was identified as a product from reaction of DNA with N-ethyl-N-nitrosourea, by procedures parallel to those reported previously for the methyl homologue produced by N-methyl-N-nitrosourea. 2. Enzymic degradation to yield alkyl phosphotriesters from DNA alkylated by these carcinogens and by dimethyl sulphate and ethyl methanesulphonate was studied quantitatively, and the relative yields of the triesters dTp(Alk)dT were determined. The relative reactivity of the phosphodiester group dTpdT to each of the four carcinogens was thus obtained, and compared with that of DNA overall, or with that of the N-7 atom of guanine in DNA. Relative reactivity of the phosphodiester group was lowest towards dimethyl sulphate, the least electrophilic of the reagents used, and was highest towards N-ethyl-N-nitrosourea, the most electrophilic reagent. 3. The nature of the alkyl group transferred also influenced reactivity of the phosphodiester site, since this site was relatively more reactive towards ethylation than would be predicted simply from the known Swain-Scott s values of the alkylating agents. It was therefore suggested that the steric accessibility of the weakly nucleophilic phosphodiester group on the outside of the DNA macromolecule favours its reaction with ethylating, as opposed to methylating, reagents. 4. Taking a value of the Swain-Scott nucleophilicity (n) of 2.5 for an average DNA nucleotide unit [Walles & Ehrenberg (1969) Acta Chem. Scand. 23, 1080-1084], a value of n of about 1 for the phosphodiester group was deduced, and this value was found to be 2-3 units less than that for the N-7 atom of guanine in DNA. 5. The reactivity of DNA overall was markedly high towards the alkylnitrosoureas, despite their relatively low s values. This was ascribed to an electrostatic factor that favoured reaction of the negatively charged polymer with alkyldiazonium cation intermediates.

(Acylaryloxy)acetic acid diuretics. 2. (2-Alkyl-2-aryl-1-oxo-5-indanyloxy)acetic acids.

Abstract: The introduction of an aryl group at the 2 position of the uricosuric diuretics, (1-oxo-2-alkyl-5-indanyloxy)acetic acids, provided compounds with markedly increased potency over their monosubstituted precursors. These compounds were synthesized either by arylation of the corresponding 2-alkyl-5-methoxy-1-indanones with diaryliodonium salts or by alkylation of the 2-aryl-5-methoxy-1-indanones which were cleaved to the corresponding phenols and then converted to the desired oxyacetic acids. Systematic structural variation of the 2-arylindanyloxyacetic acids provided aryl-substituted compounds with varying degrees of uricosuric and diuretic activity.

CH-Acidität in α-Stellung zum N-Atom in N,N-dialkylamiden mit sterisch geschützter Carbonylgruppe zur nucleophilen minoalkylierung

Abstract: CH-Acidity in α-position to the N-Atom ofN, N-Dialkylamides withSterically ProtectedCarbonyl Groups Contribution to the Nucleophilic Amino Alkylation Sterically protected amides 1 such as the 2,4,6-triisopropyl-benzoic acid derivatives 3, 8b and 10 undergo readily H/Li-exchange with s-butyllithium at the CH3N- or CH2N-groups. The resulting organolithium compounds (cf. 9, 11) are alkylated and hydroxyalkylated with primary haloalkanes, aldehydes, and ketones under chain elongation in the amine position of the amides. The (E/Z)-rotamers of the dialkylamides 7 and 8are separated by chromatography; the amides 4–6, 12, and 13 formally derived from β-hydroxyamines are obtained in the (Z)-form only. The configurational (E/Z)-assignments follow from NMR. and IR. data. The erythro and threo configuration of the two diastereomeric amides 12a and 12b are tentatively concluded from Eu(fod)3-1H-NMR.-shift experiments. The results strongly suggest that the H/Li-exchange takes place regioselectively at the CHN group which is in cis-position to the CO double bond (14). The methyl 2,4,6-tri(t-butyl)benzoate (18) can also be deprotonated to the lithium acyloxymethanide 19 which is trapped by alkylation with 1-iodooctane (20). – The steric protection of the carbonyl groups in the products 4–8, 10, 12, 13, and 20 prevents their ready hydrolysis to amines and alcohols, respectively. Therefore, triphenylacetic acid derivatives 21 rather than 2,4,6-triisopropylbenzoic acid derivatives for use in the electrophilic substitution of equation (1) are recommended. The trityl group in 21 may be considered a C-leaving-group (CC protective group, cf. 22, 23). The acetamide 25 reacts readily (26) and then with electrophiles to give products 27a–c. As shown in the Table, the amides 27 are cleaved under a variety of conditions with formation of triphenylmethane. LiAlH4 produces a tertiary amine, CH3Li a secondary amine, and dissolving alkali metals/naphthalene under aprotic conditions mixtures of secondary amine and its formamide (hydrolysed by acid treatment). Thus the overall process (2) is feasible.

Stoichiometric versus catalytic use of copper(I) salts in the synthetic use of main group organometallics

Abstract: We review some applications of copper derivatives as synthetic tools: stoichiometric organocopper reagents and organomagnesium derivatives in the presence of catalytic amounts of copper salts are able to give a regioselective addition on to acetylenic substrates and to alkylate alkyl or vinyl halides, bromohydrines, their tosylates and carboxylates, and a large variety of allylic substrates.

Polyalkylaromatics undegraded during alkylation

Abstract: Process for the production of undegraded alkylated aromatic compounds by alkylating an aromatic compound with a C 3 or higher olefin polymer having terminal ethylene units

The influence of protonation or alkylation of the phosphate group on the e.s.r. spectra and on the rate of phosphate elimination from 2-methoxyethyl phosphate 2-yl radicals.

Abstract: SummaryThe e.s.r. spectra of 1-yl, 2-yl and 3′-yl methoxyethyl phosphate radicals derived from CH3OCH2CH2-OPO3H2 by hydrogen abstraction have been measured in aqueous solutions and the hyperfine constants determined. The coupling constants vary strongly with protonation or alkylation of the phosphate group.The 2-yl radicals eliminate phosphate. The rate-constants for the elimination (ke) have been estimated by e.s.r. measurements and by product studies as a function of pH using 60Co γ-radiolysis. The ke values vary from ∼0·3 s−1 for the CH3OĊHCH2OPO—3 radical and ∼103 s−1 for CH3OĊHCH2OPO3H−, to ∼3 × 106 s−1 for CH3OĊHCH2OPO3H2. Alkylation of the phosphate group increases the elimination rate-constant to a similar extent as protonation. The results support a recent mechanism which described the OH-radical-induced single-strand breaks of DNA in aqueous solution starting from the C-4′ radical of the sugar moiety. It is further concluded the C-4′ radical of DNA eliminates the 3′-phosphate group faster than t...

Preparation and template activities of polynucleotides containing O2- and O4-alkyluridine.

Abstract: O2-Ethyl-UDP and O4-methyl-UDP have been prepared and copolymerized in various proportions with UDP or CDP, using polynucleotide phosphorylase. The copolymers were used as templates for DNA-dependent RNA polymerases in the presence of Mn2+. Both of the O-alkylated uridines caused a similar misincorporations. When copolymerized with U they led to incorporation of CMP and GMP into the poly(A). No AMP or UMP incorporation seemed to be caused by the introduction of O-alkyluridines into either poly(U) or poly(C). The mispairing of O2- and O4-alkyluridine to behave like C or G represents mutagenic events. O2 alkylation of U or T is, in contrast to O4 alkylation, a relatively frequent result of treatment of double-stranded nucleic acids with N-nitroso alkylating agents. In single-stranded nucleic acids both O2 and O4 alkylations of U and T occur to similar extents. Thus, the observed mutagenic effects of O2 and O4 alkylation of U may be involved in the high carcinogenicity of these alkylating agents.

By-product analogues for bovine carboxypeptidase B.

Abstract: A series of monocarboxylic and dicarboxylic acid sulfur-containing by-product analogues of lysine and arginine has been synthesized and tested as competitive inhibitors of bovine carboxypeptidase B. The most effective derivatives were guanidinoethylmercaptosuccinic acid and aminopropylmer-captosuccinic acid with Kis of 4 and 8 X 10(-6) M, respectively. Kinetics studies established the pure competitive nature of the inhibition. Mixed studies with the alkylating reagents bromoacetyl-D-arginine and bromoacetamidobutylguanidine established their efficiency in protecting the active-center glutamic acid and tyrosine of bovine carboxypeptidase B, respectively, from irreversible alkylation. Kinetic studies with bovine carboxypeptidase A and porcine carboxypeptidase B showed a lack of efficiency for A and high degree of efficiency for B.

Stabilized polymer composition

Abstract: A stabilized synthetic polymer composition comprising (1) 100 parts by weight of a synthetic polymer, (2) 0.001 to 5 parts by weight of a poly(alkylated alkenylphenol) composed substantially of monomeric units represented by the following formula (I) ##STR1## wherein R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; R 1 represents an alkyl group having 1 to 18 carbon atoms; and R 2 represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms; and (3) 0.001 to 5 parts by weight of an auxiliary stabilizer selected from the group consisting of polyhydric alcohol esters of alkylthioalkanoic acids, polyesters of thiodipropionic acid and organic phosphite compounds.

5-O-Alkylated derivatives of 5-hydroxy-2'-deoxyuridine as potential antiviral agents. Anti-herpes activity of 5-propynyloxy-2'-deoxyuridine.

Abstract: Alkylation of 5-hydroxyuridine or 5-hydroxy-2'-deoxyuridine with various activated alkylating agents in the presence of 1 equiv of NaOH gave a series of new nucleoside analogues which were evaluated for antiviral activity against vaccinia virus, herpes simplex-1 virus, and vesicular stomatitis virus in both primary rabbit kidney cells and human skin fibroblasts. One of these analogues, 5-propynyloxy-2'-deoxyuridine, was a potent inhibitor of herpes simplex virus. Structure-activity considerations suggest that the anti-herpes activity is dependent on the integrity of the acetylene group since substitution of phenyl, p-nitrophenyl, vinyl, carboxamido, or carboxyl for the triple bond led to diminished antiviral activity.

Zeolite catalyst and alkylation process

Abstract: An improved alkylation catalyst is provided exemplified by a type X or Y zeolite with cesium, rubidium or potassium cations, and with a boron or phosphorous component added. The catalyst is useful in producing styrene from toluene and methanol.

Synthèse d'alcools acétyléniques par alkylation d'hydroxy‐ω‐alkynes‐1

Abstract: Synthesis of acetylenic alcohols by alkylation of ω-hydroxy-1-alkynes In liquid ammonia and with lithium amide, the alkylation of an ω-hydroxyl-alkyne proceeds with good yield with primary or secondary alcohols and with fair yield with tertiary alcohols. It is a very convenient way to prepare many substituted acetylenic alcohols.

Improved Synthesis of Decarboxylated S-Adenosylmethionine and Related Sulfonium Compounds

Abstract: Decarboxylated S-adenosyl-L-methionine and its nine analogs have been prepared by a modified method of Jamieson including alkylation of the appropriate aminoalkyl-adenosyl thioether with alkyl iodides in a mixture of formic and acetic acids in the presence of silver perchlorate. The use of silver perchlorate allowed various combinations of the thioether and the alkyl iodide, and prompted the reaction. The sulfonium compounds were obtained as a white hygroscopic powder in 99% ethanol after purification by silica gel column chromatography with a solvent system of butanol-acetic acid-water (1 : 1 : 1). The chemical and physical data of the sulfonium compounds supported a general structure containing 2 mol of sulfuric acid and 0.5 mol of ethanol. The nuclear magnetic resonance data showed the existence of sulfonium diastereoisomers.