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Showing papers on "Alkylation published in 1973"



Journal ArticleDOI
TL;DR: In this paper, the potassium salts of indole, pyrrole, and 2,5-dimethylpyrrole were converted into N-alkyl derivatives in high yield in dimethyl sulphoxide by use of iodomethane, iodoethane, 1-iodopropane, and benzyl bromide.
Abstract: The potassium salts of indole, pyrrole, and 2,5-dimethylpyrrole were converted into N-alkyl derivatives in high yield in dimethyl sulphoxide by use of iodomethane, iodoethane, 1-iodopropane, and benzyl bromide. Dehydrohalogenation occurred when 2-iodo- and 2-bromo-2-methylpropane were used; when 2-iodopropane was employed alkylation and dehydrohalogenation were observed.

110 citations


Journal ArticleDOI
TL;DR: The mechanism of action of papain is reconsidered and it is concluded that the acylation and deacylation steps are not symmetrical processes, and they are one-encounter type reactions.
Abstract: The reaction of the thiol group of papain with chloroacetamide, iodoacetamide, d- and l-2-bromopropionamides was studied. In the acidic pH-range the reaction rate is higher than expected for an ordinary SH-group and shows a double-sigmoid pH-rate profile. In addition to the already described pKa of 8.5, we found a pKa of 4.0. This indicates that in the pH-range where the enzyme is catalytically active the thiol group of Cys-25 interacts with some amino acid side chain, presumably with the imidazole group of the neighboring His-159. In the light of the X-ray diffraction studies (Drenth et al., 1971), it is probable that the anomalous PKa of His-159 is due to its interaction with Trp-177. The comparison of the pH-rate profiles of d- and l-2-bromopropionamide reactions indicates that there is no sifgnificant alteration in the geometry of the active site around pH 4, whereas at slightly alkaline pH structural changes can be observed. 2H2O has no effect on the rate constants of the alkylation reaction. This rules out the possibility of general base catalysis by the imidazole group of His-159. The experimental data indicate that the dissociated thiol group forms an ion pair with the protonated imidazole group. On the basis of the formation of thiolate-imidazolium ion pair, the mechanism of action of papain is reconsidered. It is concluded that the acylation and deacylation steps are not symmetrical processes, and they are one-encounter type reactions. The interaction between His-159 and Trp-177 may be important in the catalysis.

103 citations


Journal ArticleDOI
TL;DR: In this paper, the reaction of ketone enolates with alkylating or silylating reagents can be used to prepare O-alkyl or O-silyl vinyl ethers.

98 citations



Journal ArticleDOI
TL;DR: In this article, a number of dithioesters RC(S)SR′ (Ralkyl, aryl, 2-thienyl; R′ = alkyl, allyl or propargyl) can be obtained in good yields by reaction of RMgX (X = Cl or Br) in tetrahydrofuran with carbon disulfide.
Abstract: A number of dithioesters RC(S)SR′ (Ralkyl, aryl, 2-thienyl; R′ = alkyl, allyl or propargyl) can be obtained in good yields by reaction of RMgX (X = Cl or Br) in tetrahydrofuran with carbon disulfide, followed by alkylation with alkyl iodides, allyl bromide or propargyl bromide.

84 citations





Journal ArticleDOI
TL;DR: The mass spectra of O(6)-alkyl-2'-deoxyguanosines (methyl and ethyl) and of the corresponding 2-amino-6-alkoxypurines were determined and the reaction of diazomethane with thymidine afforded O(4)-methylthymidine, in addition to the previously detected 3-methylthylidine.
Abstract: The reaction in ether–methanol between 2′-deoxyguanosine and diazomethane or its ethyl or n-butyl homologue gives 1-, O6- and 7-alkyl-2′-deoxyguanosine. N2,O6-Dimethyl-2′-deoxyguanosine was also detected. The hydrolysis of the methyl and the ethyl derivatives gives the corresponding alkylguanines: the O6-alkyl-2′-deoxyguanosines were sequentially hydrolysed, first to 2-amino-6-alkoxypurines, subsequently to guanine. The mass spectra of O6-alkyl-2′-deoxyguanosines (methyl and ethyl) and of the corresponding 2-amino-6-alkoxypurines were determined. The reaction of diazomethane with thymidine afforded O4-methylthymidine, in addition to the previously detected 3-methylthymidine.

59 citations




Journal ArticleDOI
TL;DR: In the case of organotin enolates, heating with alkylating agents, usually gives monoalkylated products in very good yields: numerous examples with ketones and aldehydes are described.


Patent
27 Sep 1973
TL;DR: In this paper, an ALKYLATABLE ORGANIC COMPOUND is considered, in which an ALKALI METAL CONTENT of LESS THAN 3.5 WEIGHT PERCENT on a solids basis, an SIO2/AL2O/3 MOLAR RATIO of at least 7.0.
Abstract: 1. IN AN ALKYLATION PROCESS IN WHICH AN ALKYLATABLE ORGANIC COMPOUND IS CONTACTED AND REACTED WITH AN ALKYLATION AGENT IN A CATALYTIC CONVERSION ZONE CONTAINING A CATALYST COMPOSITION COMPRISING AT LEAST ONE HYDROGENATION AGENT OF THE GROUP OF NICKEL, PLATINUM, PALLADIUM, RUTHENIUM AND RHODIUM AND THREE-DIMENSIONAL CRYSTALLINE ZEOLITIC MOLECULAR SIEVE HAVING A PORE DIAMETER LARGE ENOUGH TO ADSORB ORTHO-DIETHYLBENZENE, AN ALKALI METAL CONTENT OF LESS THAN 3.5 WEIGHT PERCENT ON A SOLIDS BASIS, AN SIO2/AL2O/3 MOLAR RATIO OF AT LEAST 7.0. SAID CONTACT AND REACTION BEING CONTINUED UNTIL THE ALKYLATION ACTIVITY OF THE CATALYST HAS DECREASED, THE IMPROVEMENT WHICH COMPRISES PERIDICALLY CONTACTING A DHYDROGENATING THE CATALYST COMPOSITION AT A TEMPERATURE OF FROM 80*F. TO 572*F. WITH A LIQUID SOLUTION OF HYDROGEN IN A SATURATED HYDROCARBON HAVING FROM 4 TO 12 CARBON ATOMS, SAID SOLUTION CONTAINING AT LEAST 0.1 MOLE PERCENT DISSOLVED HYDROGEN, UNTIL THE ALKYLATION ACTIVITY OF THE CATALYST IS IMPROVED.

Patent
27 Sep 1973
TL;DR: The alkylation activity of a zeolite-base isoparaffin alkyllation catalyst is maintainable for very long periods at commercially feasible levels by including a Group VIII metal hydrogenation agent in the catalyst composition as mentioned in this paper.
Abstract: The alkylation activity of a zeolite-base isoparaffin alkylation catalyst is maintainable for very long periods at commercially feasible levels by including a Group VIII metal hydrogenation agent in the catalyst composition and periodically hydrogenating the partially deactivated catalyst by contact with hydrogen in the gas phase.




Journal ArticleDOI
TL;DR: A high yield, experimentally convenient method for the controlled alkylation of lactone enolates is described in this article, where a high yield method is used for controlling the alkylation process.
Abstract: A high yield, experimentally convenient method for the controlled alkylation of lactone enolates is described.



Journal ArticleDOI
TL;DR: S-Carboxymethylcysteine, formed by the reaction of iodoacetic acid with cysteines, was found to undergo intramolecular cyclization to yield 3-oxo-(2H,3H,5H,6H-1,4-thiazine)-5-carboxylic acid.
Abstract: S-Carboxymethylcysteine, formed by the reaction of iodoacetic acid with cysteine, was found to undergo intramolecular cyclization to yield 3-oxo-(2H,3H,5H,6H-1,4-thiazine)-5-carboxylic acid. The cyclization was studied under various conditions and the product was isolated and characterized. S-Carboxyethylcysteine, formed by the reaction of 3-bromopropionic acid with cysteine, did not undergo the cyclization reaction. The use of 3-bromopropionic acid was examined as an alternative to iodoacetic acid for the protection and determination of protein thiol groups.


Journal ArticleDOI
TL;DR: In this paper, 3,5-dimethylisoxazole (1) was alkylated with sodium amide in liquid ammonia to give 3,methyl-5-alkyl isoxazoles.
Abstract: 3,5-Dimethylisoxazole (1) was alkylated with sodium amide in liquid ammonia to give 3-methyl-5-alkylisoxazoles By di- and tri-alkylation reactions using excess sodium amide, isoxazoles having secondary and tertiary alkyl groups at 5-position could be obtained The hydrogenolysis and hydrolysis of these isoxazoles were also studied

Journal ArticleDOI
TL;DR: Alkylation of enamines prepared from 2-phenylpropanal and L-proline derivatives, with methyl vinyl ketone, was successful and gave, after hydrolysis and cyclization, optically active (+)-4-methyl-4phenyl-2-cyclohexanone ((+)-IV) as mentioned in this paper.
Abstract: Alkylation of enamines prepared from 2-phenylpropanal and L-proline derivatives, with methyl vinyl ketone, was successful and gave, after hydrolysis and cyclization, optically active (+)-4-methyl-4-phenyl-2-cyclohexanone ((+)-IV). The effects of L-proline derivatives, solvents, and reaction temperature on the alkylation were discussed. Under selected conditions the optical yield reached about 50%. Asymmetric induction was clearly thermodynamically controlled.


Journal ArticleDOI
W. Dünges1
TL;DR: In this paper, a new alkylation method is proposed, where organic solutions of fatty acids, phenols or barbituric acids are refluxed with an alkylating reagent and solid K2CO3.
Abstract: A new alkylation method is proposed. Organic solutions of fatty acids, phenols or barbituric acids are refluxed with an alkylating reagent and solid K2CO3. The reaction mixture is injected directly into the gas chromatograph. The scope of this convenient method for quantitative and qualitative analyses is considerable as different classes of alkylating agents can be used.

Journal ArticleDOI
TL;DR: A series of new 4-aryl-1,3-dihydro-2H-1.5-benzodiazepine-2-thiones was synthesized by condensing the 3-3-dimercapto-1-aryl -2-propen-1 -ones with o-phenylenediamine.

Journal ArticleDOI
TL;DR: In this paper, a method for N-alkylation of imidazole, benzimidazoles, pyrazole, 1,2,4-triazole and benzotriazole using trimethyl, triethyl, and tri-n-butyl phosphates as alkylating agents is described.
Abstract: A new method for N-alkylation of imidazole, benzimidazole, pyrazole, 1,2,4-triazole, and benzotriazole using trimethyl, triethyl, and tri-n-butyl phosphates as alkylating agents is described. All these heterocycles are easily converted into the corresponding N-alkyl derivatives in 45–90% yields. Predominant alkylation at N-1 was observed in both triazoles.