Catalytic alkylation of furan by 2-methylbut-1-ene

Conclusions The authors have studied the alkylation of furan by 2-methylbut-1-ene. We found out how the yields of the monoamyl derivatives and the ratio of the 2- and 3-monoisomers formed depend on the temperature and the amount of catalyst.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2618–2620, November, 1968.Deceased.     

Alkylboronic acids as alkylating agents: photoredox-catalyzed alkylation reactions assisted by K3PO4

Despite the ubiquity of alkylboronic acids in organic synthesis, their utility as alkyl radical precursors in visible-light-induced photocatalytic reactions is limited by their high oxidation potentials. In this study, we demonstrated that an inorganophosphorus compound can modulate the oxidation potentials of alkylboronic acids so that they can act as alkyl radical precursors. We propose a mechanism based on the results of fluorescence quenching experiments, electrochemical experiments, ¹¹B and ³¹P NMR spectroscopy, and other techniques. In addition, we describe a simple and reliable alkylation method that has good functional group tolerance and can be used for direct C–B chlorination, cyanation, vinylation, alkynylation, and allylation, as well as late-stage functionalization of derivatized drug molecules. Notably, alkylboronic acids can be selectively activated in the presence of a boronic pinacol ester.

An alkylation method using inorganophosphorus-activated alkylboronic acids to act as alkyl radical precursors has been developed. This method can be used for direct C–B chlorination, cyanation, vinylation, alkynylation, and allylation.     

α-Polyfluroalkylbenzyl dichlorophosphates as alkylating agents in alkylation of aromatic compounds

On heating, α-polyfluoroalkylbenzyl dichlorophosphates alkylate mesitylene, durene, and naphthalene to give the corresponding aromatic compounds containing the α-polyfluoro-alkylbenzyl fragment as a substituent. Deceased. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1866–1869, September, 1998.     

α-Polyfluoroalkylbenzyl dichlorophosphates as alkylating agents in the alkylation of polyfluorinated phenols

Conclusions -Polyfluoroalkylbenzyl dichlorophosphates alkylate polyfluorinated phenols with the formation of the corresponding ethers.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1923–1925, August, 1985.     

Catalytic alkylation of tetralin by nonene-1 in the presence of aluminum

Summary Isononyl- and diisononyltetralins are formed in the alkylation of tetralin by nonene-1 in the presence of metallic aluminum activated by nonyl bromide.     

Catalytic alkylation of cresols with propanol-1

Study of the reaction of alkylation of ortho-, meta-, and para-cresols with propanol-1 in the presence of ferrite cobalt and manganese catalysts is reported. The effect of the catalyst composition and reaction conditions on the yield and isomeric composition of the resulting propyl derivatives of cresol was examined and the main and side conversions occurring in the catalysis were determined.     

Characterization of strong complexing agents in natural waters by liquid-liquid extraction

The solvent extraction method for characterization of strong complexing agents in natural waters has been developed. The titration curve the relationship between the concentration of a metal added in a sample solution and that of the metal in the organic phase after extraction, has been modelled on the basis of Ringbom's theory. The concentration of the metal in the organic phase is easily calibrated by the activities of the radioisotopic spike. The conditional stability products for complexation of natural ligands with cobalt (⁵⁷Co), manganese (⁵⁴Mn) and zinc (⁶⁵Zn) were calculated from the titration curves.     

HTS-1分子筛表面酸催化的探针反应研究

 以 1,2-环氧环己烷水解为主要探针反应研究了钛硅分子筛 HTS-1 的表面酸催化性能. 结果表明, HTS-1 表面酸中心具有较高的催化活性, 它的扩散性能和溶剂极性对反应活性的影响很大. 还采用吸附吡啶的红外光谱和紫外光谱对 HTS-1 催化剂表面酸性进行了定性和定量分析. 这些结果不仅拓展了 HTS-1 在精细有机合成中的应用, 而且为有效提高 HTS-1 的催化氧化性能提供了依据.     

Speciation and bioavailability of selenium in yeast-based intervention agents used in cancer chemoprevention studies

This study investigated the speciation and bioavailability of selenium in yeast-based intervention agents from multiple manufacturers from several time points. Sources of selenized yeast included Nutrition 21 (San Diego, CA), which supplied the Nutritional Prevention of Cancer (NPC) Trial from 1981-1996; Cypress Systems (Fresno, CA; 1997-1999); and Pharma Nord (Vejle, Denmark; 1999-2000), which supplied the Prevention of Cancer by Intervention by Selenium (PRECISE) Trial pilot studies. The low-molecular-selenium species were liberated from the samples by proteolytic hydrolysis followed by separation by ion exchange liquid chromatography and detection by inductively coupled plasma-mass spectrometry. The results for the NPC tablets showed that selenomethionine, together with 3 unidentified selenium compounds, were predominant in the sample hydrolysates. The relative amounts of the 4 selenium species varied (p < 0.05) among several of the 7 tablet batches used during the course of the NPC Trial. In comparison, 5 batches of more recently produced selenized yeasts, which were used as a source of selenium in the PRECISE and other trials, contained less of the unknown compounds and more selenomethionine at 54-60% of the total selenium in the yeasts. One batch of yeast, however (from 1985), which originated from the same producer as the yeast used in the NPC tablets, contained only 27% of selenium in the sample as selenomethionine. Human subjects receiving 200 microg selenium/day in the UK PRECISE Pilot Trial showed a higher concentration (p < 0.01) and higher increase from baseline in plasma selenium than did the same dosage used in the NPC Trial. Differences in intake, speciation, or bioavailability of selenium from the yeast-based supplements in the population groups studied may explain this. Furthermore, the selenium concentration in whole blood from the Danish PRECISE Pilot Trial was higher (p < 0.001) than that obtained with synthetic L-selenomethionine in a comparable group of Danes, both groups having been treated with 300 microg selenium/day.     

Novel antiparasitic agents derived by modification of a new natural product series

Regioselective reactions on the C5-, C7- and C23-hydroxyl groups of the macrocyclic lactones (1), (3) and (4) are described.     

Sequence-specific alkylation of double-strand human telomere repeat sequence by pyrrole-imidazole polyamides with indole linkers

We designed and synthesized pyrrole (Py)-imidazole (Im) hairpin polyamide 1-(chloromethyl)-5-hydroxy-1,2-dihydro-3H-benz[e]indole (seco-CBI) conjugates 1 and 2, which target both strands of the double-stranded region of the human telomere repeat sequences, 5'-d(TTAGGG)(n)-3'/5'-d(CCCTAA)(n)-3'. High-resolution denaturing polyacrylamide gel electrophoresis demonstrated that conjugates 1 and 2 alkylated DNA at the 3' A of 5'-ACCCTA-3' and 5'-AGGGTTA-3', respectively. Cytotoxicities of conjugates 1 and 2 were evaluated using 39 human cancer cell lines; averages of log IC(50) values for conjugates 1 and 2 were -6.96 (110 nM) and -7.24 (57.5 nM), respectively. Conjugates 1 and 2 have potential as antitumor drugs capable of targeting telomere repeat sequence.     

Selective N-1 alkylation of unsymmetrically substituted pyrazoles

A series of C-substituted pyrazoles have been N-alkylated. The alkylation occurs preferentially at the N-1 position when a tert-butyl group is present at the pyrazole C-3 position.     

Homolytic alkylation of succinic anhydride with 1-alkenes

Conclusions The reaction of succinic anhydride with C₈−C₁₈-alkenes, initiated by tert-butyl peroxide, leads to the formation of n-alkylsuccinic anhydrides, the yield of which under the optimum conditions is 50–75%. N.D. Zelinskii Institute of Organic Chemistry, Academy of Sciences of the USSR, Moscow. Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2389–2392, October, 1976.     

Preparation of α-substituted allylboronates by chemoselective iridium-catalyzed asymmetric allylic alkylation of 1-propenylboronates

Chiral α-substituted allylic boronates are attractive reagents that add to aldehydes with very high stereoselectivity. This study examined the feasibility of an improved method of preparation based on the catalytic asymmetric allylic alkylation of simple 3-hydroxy-1-propenylboronate derivatives with malonate anions. Whereas palladium catalysis failed in promoting the desired process, iridium catalysis led to a regioselective formation of the desired, branched allylboronates with up to 84% ee using a chiral monophosphoramidite ligand. This allylation reagent adds to aldehydes with high chirality transfer. A diastereoselective alkoxycyclization on the resulting homoallylic alcohols allows a separation of the epimeric E/Z isomers.     

Screening for diuretics in human urine by gas chromatography-mass spectrometry with derivatisation by direct extractive alkylation

A rapid, sensitive and reliable gas chromatographic-mass spectrometric (GC-MS) screening procedure for diuretics in human urine has been developed. The procedure uses derivatisation by extractive methylation directly from the urine. The suitability of a number of phase transfer reagents and solvents were studied for the detection of sixteen diuretics. The results obtained indicate that the screening procedure employing tetrahexylammonium hydrogensulphate at pH 12 with methyl iodide in toluene at room temperature was the most effective. This method gives selectivity and sensitivities down to 0.03-0.1 microgram/ml and provides a substrate suitable for GC-MS confirmation without further manipulation. The application of the method is demonstrated by the screening of urine for bumetanide, ethacrynic acid, acetazolamide, chlorothiazide and hydrochlorothiazide.     

Diastereoselective alkylation reactions of 1-methylcyclohexa-2,5-diene-1-carboxylic acid

The deprotonation and alkylation of 1-methylcyclohexa-2,5-diene-1-carboxylic acid has been investigated under a range of conditions. In all cases, the formation of compounds 14 was found to be completely stereoselective, although compound 14c was formed as an impurity when alkyl iodides were used as electrophiles, and doubly-alkylated compounds 17 were formed in some cases when alkyl bromides were used.     

Concise synthesis of aryl-C-nucleosides by Friedel-Crafts alkylation

A fast and simplified synthesis of 1',2'-dideoxy-1'-pyrenyl-riboside and several other C-nucleosides is shown. Shelf-stable 1-O-methyl-3,5-di-O-toluoyl-2-deoxyribose is demonstrated to serve as a versatile glycosyl donor in Lewis acid promoted Friedel-Crafts alkylations of unsubstituted pyrene and other inexpensive arenes such as fluorene and methylnaphthalene. The reaction conditions favour the formation of beta-configurated C-nucleosides which renders additional epimerisation steps unnecessary. As a result, protected beta-aryl-C-nucleosides are available directly from non-substituted arenes in three steps overall.