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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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Journal ArticleDOI
TL;DR: These are the first direct reaction rate measurements of nucleophilic addition to the parent o-quinone methide, and a thermal and photochemical reversibility of the alkylation process opens a new perspective for the use and application of such adducts as o-QM molecular carriers.
Abstract: o-Quinone methide (1) has been produced in water both thermally and photochemically from (2-hydroxybenzyl)trimethylammonium iodide (2). Michael addition reactions of 1 to various amines, and sulfides, including amino acids and glutathione have been carried out, obtaining alkylated adducts (3-16) in fairly good to quantitative yields. The reaction rate and selectivity of 1 toward nitrogen and sulfur nucleophiles, in competition with the hydration reaction, have been investigated at different pH by laser flash photolysis technique. The observed reactivity spans 7 orders of magnitude on passing from water (kNu = 5.8 M-1 s-1) to the most reactive nucleophile (2.8 x 10(8) M-1 s-1, 2-mercaptoethanol under alkaline conditions). These are the first direct reaction rate measurements of nucleophilic addition to the parent o-quinone methide (1). Competition experiments provided strong kinetic support to the involvement of free 1 as an intermediate in both thermal and photochemical reactions. Furthermore, several alkylation adducts regenerate 1 either by heating (9, 10, 13, and 14) or by irradiation (9, 11-13, 16). Such a thermal and photochemical reversibility of the alkylation process opens a new perspective for the use and application of such adducts as o-QM molecular carriers.

167 citations

Journal ArticleDOI
TL;DR: The Sc(OTf)3-catalyzed Friedel−Crafts alkylation reaction with an alcohol, an arenecarbaldehyde and 1,3-propanediol or their acetal as the alkylating agent affords diarylmethane or an allylbenzene derivative highly selectively as mentioned in this paper.
Abstract: The Sc(OTf)3-catalyzed Friedel−Crafts alkylation reaction with an alcohol, an arenecarbaldehyde or an arenecarbaldehyde acetal as the alkylating agent affords a diarylmethane or an allylbenzene derivative highly selectively. The salient feature of this reaction is that only a catalytic amount of Sc(OTf)3 can effect the reaction. Furthermore, Sc(OTf)3 is recoverable and reusable after the synthetic reaction. The Sc(OTf)3-catalyzed benzylation using an arenecarbaldehyde and 1,3-propanediol or their acetal affords diarylmethane as a sole product in excellent yields in sharp contrast to the original Friedel−Crafts reaction. Since no reaction occurs in the absence of 1,3-propanediol, the reaction is considered to proceed through a redox process including a hydride shift. The hydride shift mechanism is strongly supported by the experimental evidence. The reaction of benzaldehyde with benzene in the presence of 1,3-propanediol-1,1,3,3,-d4 gives rise to the deuterium incorporation into the benzylic carbon of diph...

167 citations

Journal ArticleDOI
TL;DR: In this paper, the electrophilic α-alkylation of ketones with alcohols was accomplished by a [Ru(DMSO) 4 ]Cl 2 catalyzed process, water being the only wasted material.

167 citations

Journal ArticleDOI
TL;DR: This review summarizes the early adventures and recent advancements in catalytic transformation of unactivated C(sp3)-H bonds into C( sp3)-C(sp2) bonds, representing the future trend in green and atom-economic chemistry.
Abstract: The construction of carbon–carbon bonds is a central tenet of modern synthetic chemistry. Metal-catalyzed C–H functionalization can serve as a particularly powerful tool for achieving carbon–carbon bond formation. This review summarizes the early adventures and recent advancements in catalytic transformation of unactivated C(sp3)–H bonds into C(sp3)–C(sp3) bonds. To date, three main strategies have emerged to enable this transformation, namely, metallocarbene-triggered C(sp3)–H alkylation, auxiliary-directed C(sp3)–H alkylation, and photo-induced C(sp3)–H alkylation. Compared with traditional cross-coupling reactions having both coupling partners activated with functional groups or base-promoted enolate chemistry, catalytic alkylation of unactivated C(sp3)–H bonds for C(sp3)–C(sp3) bond formation not only offers novel disconnections in retrosynthetic analysis, but also represents the future trend in green and atom-economic chemistry.

166 citations

Journal ArticleDOI
TL;DR: An ionic cobalt-PNP complex is developed for the efficient α-alkylation of ketones with primary alcohols for the first time and was successfully applied to the greener synthesis of quinoline derivatives while using 2-aminobenzyl alcohol as an alkylating reagent.

166 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023652
20221,161
2021561
2020516
2019630
2018631