scispace - formally typeset
Search or ask a question
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.


Papers
More filters
Journal ArticleDOI
TL;DR: In this paper, the cross-coupling of aryl boronic acids and alkanethiols mediated by copper(II) acetate and pyridine in anhydrous dimethylformamide has been used for the synthesis of the sulfide of cysteine.

282 citations

Journal ArticleDOI
TL;DR: In the presence of iridium catalysts, inactive C−H and N−H bonds have been transformed into C−C and N-C bonds in dehydrative alkylation using alcohols, allylation using allyl carbonates, and alkenes as mentioned in this paper.
Abstract: Over the past few years, iridium complexes have been widely used in the direct functionalization of unactivated bonds. In the presence of iridium catalysts, inactive C–H and N–H bonds have been transformed into C–C and N–C bonds in dehydrative alkylation using alcohols, allylation using allyl carbonates, and alkylation using alkenes. Enantioselective variants of some reactions have also been reported.

281 citations

Journal ArticleDOI
TL;DR: It is confirmed that the presence of a chiral center on the N-alkyl substituent may lead to enantiomers which differ in their levels of binding (compounds 54, 57 and 55, 56).
Abstract: In order to establish the structural requirements for binding to the brain cannabinoid receptor (CB1), we have synthesized numerous fatty acid amides, ethanolamides, and some related simple derivatives and have determined their Ki values. A few α-methyl- or α,α-dimethylarachidonoylalkylamides were also examined. In the 20:4, n-6 series, the unsubstituted amide is inactive; N-monoalkylation, at least up to a branched pentyl group, leads to significant binding. N,N-Dialkylation, with or without hydroxylation on one of the alkyl groups, leads to elimination of activity. Hydroxylation of the N-monoalkyl group at the ω carbon atom retains activity. In the 20:x, n-6 series, x has to be either 3 or 4; the presence of only two double bonds leads to inactivation. In the n-3 series, the limited data reported suggest that the derived ethanolamides are either inactive or less active than comparable compounds in the n-6 series. Alkylation or dialkylation of the α carbon adjacent to the carbonyl group retains the level...

278 citations

Journal ArticleDOI
TL;DR: Findings are reported on the development of such C H bond functionalization reactions, which allowed for the efficient conversion of primary and secondary alkyl halides and proved applicable to neopentyl-substituted electrophiles.
Abstract: Direct arylation of arenes by C H bond cleavage, which is attractive because of its ecologically and economically benign nature, is an increasingly viable alternative to conventional cross-coupling reactions with stoichiometric amounts of organometallic reagents. 2] However, while the development of stabilizing ligands allowed for the use of unactivated alkyl halides in traditional cross-coupling chemistry, generally applicable methodologies for intermolecular regioselective direct alkylations of arenes with alkyl halides by C H bond cleavage have proven elusive. Recently, we reported on the beneficial effect of carboxylic acids as additives in ruthenium-catalyzed direct arylation 11] with aryl bromides, chlorides, or tosylates. Given the significantly improved activity of the in situ generated catalytic system, we became interested in exploring its use for unprecedented ruthenium-catalyzed direct alkylations with unactivated alkyl halides 15] as electrophiles. Herein, we report our findings on the development of such C H bond functionalization reactions, which allowed for the efficient conversion of primary and secondary alkyl halides and proved applicable to neopentyl-substituted electrophiles. At the outset of our studies, we probed various additives in the ruthenium-catalyzed direct alkylation of 2-pyridyl benzene (1a), employing unactivated alkyl bromide 2 a in NMP as solvent (Table 1). Different phosphines did not significantly affect the outcome of the envisioned reaction (Table 1, entries 1–4). On the contrary, more promising results were obtained when catalytic amounts of carboxylic acids were used as additives (Table 1, entries 5–9). The alkylsubstituted, sterically hindered acid 1-AdCO2H gave the best results (Table 1, entry 9). Reactions performed in toluene as solvent proceeded less efficiently (Table 1, entry 10), and other solvents, such as THF, 1,4-dioxane, DMSO, or N,N-dimethylacetamide, gave considerably lower yields of desired product 3a. As an economically attractive alternative, RuCl3·n H2O [17] could be employed as catalyst precursor (Table 1, entry 11). Importantly, direct alkylation of pyridine derivative 1a could be performed at reaction temperatures as low as 60 8C with comparable efficiencies (Table 1, entries 13–15). Finally, the use of independently prepared carboxylic ester 1-AdCO2(nHex) clearly indicated that its formation was not relevant to the generation of the catalytically active ruthenium species (Table 1, entry 16). We then explored the scope of the optimized catalytic system in the direct alkylation of pyridine derivatives 1 (Table 2). A variety of unactivated alkyl bromides bearing bhydrogen atoms enabled regioselective direct alkylations (Table 2, entries 1–8). While an alkyl iodide also led to an acceptable yield of product 3a (Table 2, entry 9), the corresponding alkyl chloride turned out to be a more challenging substrate (Table 2, entry 10). Notably, our in situ generated catalytic system was not limited to the use of primary alkyl halides but also enabled the conversion of sterically more congested secondary alkyl halides, albeit with lower yield (Table 2, entry 11). Importantly, neopentyl bromide also served as starting material for a direct alkylation (Table 2, entry 12), which indicated that mechanisms relying on either a Table 1: Optimization of ruthenium-catalyzed direct alkylation.

277 citations

Journal ArticleDOI
TL;DR: In this paper, a catalytic system consisting of [Cp ∗ IrCl 2 ] 2 /NaHCO 3 for the N-alkylation of amines with primary and secondary alcohols as alkylating reagents has been developed.

274 citations


Network Information
Related Topics (5)
Aryl
95.6K papers, 1.3M citations
97% related
Alkyl
223.5K papers, 2M citations
95% related
Enantioselective synthesis
58.1K papers, 1.6M citations
95% related
Intramolecular force
41.6K papers, 772.2K citations
93% related
Catalysis
400.9K papers, 8.7M citations
92% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023652
20221,161
2021561
2020516
2019630
2018631