Topic
Alkylation
About: Alkylation is a research topic. Over the lifetime, 29915 publications have been published within this topic receiving 464944 citations. The topic is also known as: alkylation reaction.
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TL;DR: In this article, a series of 5-substituted 1H-tetrazoles were synthesized through cycloaddition reactions between nitriles RCN and NaN3 in the presence of Cu-Zn alloy nanopowder as catalyst.
88 citations
TL;DR: The utility of the alkylation of the imino functional group is extended to include diastereoand enantioselective variants that yield precursors for a number of pharmacologically active classes of compounds.
Abstract: The past few years have witnessed a profusion of highly efficient, catalytic, enantioand diastereoselective alkylations of carbonyl compounds.1 At the present time, the alkylation of the imino functional group presents a timely challenge in asymmetric catalysis, and recent work has focused on enol silanes, silyl ketene acetals, and TMSCN as carbon-based nucleophiles.2 We recently reported a means to alkylate R-imino ester 1 in up to 98% ee with enol silanes using chiral catalytic late-transition-metal phosphine complexes based on Ag(I), Cu(I), Ni(II), and Pd(II) (eq 1, R′ ) H).3 The best results were obtained with the easy-toprepare catalyst (R)-Tol-BINAP-CuClO4‚(MeCN)2. In this paper, we extend the utility of our reaction to include diastereoand enantioselective variants that yield precursors for a number of pharmacologically active classes of compounds.4 Regardless of the geometry of the enol silane, in many cases, excellent anti diastereoselectivity as well as enantioselectivity (up to 99% ee) can be obtained in the reaction (eq 1).5 In fact, the precise nature of the chiral phosphines we employ is responsible for the diastereoselectivity, as certain achiral bis(triphenylphosphine)-Cu(I) complexes lead to equal amounts of anti and syn products.
88 citations
TL;DR: In this paper, a comparative study of the alkylation of benzene or toluene with MeOH or C{sub 2}H{sub 4} over a medium (ZSM-5) and a large pore ({beta}) zeolite of comparable acidities was carried out.
Abstract: A comparative study of the alkylation of benzene or toluene with MeOH or C{sub 2}H{sub 4} over a medium (ZSM-5) and a large pore ({beta}) zeolite of comparable acidities was carried out. It was observed that the reaction temperature in combination with the structure of the zeolite plays an important role in the reactions that take place. The maximum yield of either the primary or secondary alkylation products may occur at an intermediate temperature, which is lower over {beta} zeolite. Due to its pore structure, {beta} zeolite favors secondary alkylation reactions and also disproportionation reactions of the generated alkylaromatics to a higher extent than ZSM-5 does. MeOH generates both primary and secondary alkylation products, while C{sub 2}H{sub 4} favors oligomerization reactions, primary alkylation reactions, and particularly, disproportionation reactions. Toluene is more reactive than benzene. The aromatic/alkylating agent molar ratio plays an important role in the relative importance of the reactions that take place. The size of the pores of the zeolite in combination with the sizes of the aromatic hydrocarbons and the alkylating agents employed determines whether the alkylation occurs via a Langmuir-Henshelwood (LH) or Rideal-Eley (RE) mechanism. When a LH mechanism occurs, the alkylation rate passes through a maximummore » with respect to the concentration of the aromatic hydrocarbon employed; no such maximum occurs for the RE mechanism.« less
88 citations
TL;DR: Measurements of protein alkylation by matrix assisted laser desorption/ionisation‐time of flight‐mass spectrometry (MALDI‐TOF‐MS) and its implications on 2‐D gel analysis in particular and proteomics in general are discussed.
Abstract: All existing protocols for protein separation by two-dimensional (2-D) gel electrophoresis require the full reduction, denaturation, and alkylation as a precondition for an efficient and meaningful separation of such proteins Existing literature provides a strong evidence to suggest that full reduction and denaturation can be achieved in a relatively short time; the same thing, however, can not be said for the alkylation process, which the present study shows that more than 6 h are required for a complete alkylation We have used matrix assisted laser desorption/ionisation-time of flight-mass spectrometry (MALDI-TOF-MS) to monitor protein alkylation by iodoacetamide over the period 0-24 h at pH 9 The present, fast and specific MS method provided clear indication on the extent and speed of alkylation which reached approximately 70% in the first 2 min, yet the remaining 30% resisted complete alkylation up to 6 h The use of sodium dodecyl sulfate (SDS) during the alkylation step resulted in a strong quenching of this reaction, whereas 2% 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS) exerted a much reduced inhibition The implications of the present measurements on 2-D gel analysis in particular and proteomics in general are discussed
88 citations
TL;DR: A selective and catalytic mono-N-alkylation method of both aromatic and aliphatic amines using nitriles as an alkylating agent with Pd/C or Rh/C as a catalyst is described.
88 citations