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 pyridyl-supported pyrazolyl-imidazolyl ligand was used to catalyze the direct β-alkylation of secondary alcohols with primary alcohols under phosphine-free conditions.
Abstract: Manganese(I) complexes bearing a pyridyl-supported pyrazolyl-imidazolyl ligand efficiently catalyzed the direct β-alkylation of secondary alcohols with primary alcohols under phosphine-free conditions. The β-alkylated secondary alcohols were obtained in moderate to good yields with water formed as the byproduct through a borrowing hydrogen pathway. β-Alkylation of cholesterols was also effectively achieved. The present protocol provides a concise atom-economical method for C–C bond formation from primary and secondary alcohols.
124 citations
Eni1
TL;DR: The use of zeolitic catalysts in organic syntheses is reviewed with emphasis on recent developments in the areas of acid and redox catalysis and on their relationship with environmental issues as mentioned in this paper.
Abstract: The use of zeolitic catalysts in organic syntheses is reviewed with emphasis on recent developments in the areas of acid and redox catalysis and on their relationship with environmental issues. Examples of acid‐catalyzed reactions are chosen from the acylation, alkylation, hydroxyalkylation of aromatic and heterocyclic compounds and from rearrangement reactions. The epoxidation of olefins, the hydroxylation of arenes and the oxidation of O‐, S‐ and N‐functionalities with hydrogen peroxide on Ti‐zeolites illustrate catalyzed oxidations.
124 citations
TL;DR: Catalytic enantioselective alkylation promoted by a quaternary ammonium salt from cinchonine as a phase transfer catalyst is described, resulting in moderate to excellent yields with high enantiomeric excesses.
Abstract: Catalytic enantioselective alkylation promoted by a quaternary ammonium salt from cinchonine as a phase transfer catalyst is described. Treatment of cyclo beta-keto esters with alkyl halide under mild reaction conditions afforded the corresponding alpha-alkylated beta-keto esters in moderate to excellent yields with high enantiomeric excesses
124 citations
TL;DR: A practical catalytic asymmetric addition of ethyl groups to ketones using titanium tetraisopropoxide and dialkylzinc at room temperature results in enantioselective addition of the alkyl group to the ketone.
Abstract: Many catalysts will promote the asymmetric addition of alkylzinc reagents to aldehydes. In contrast, there are no reports of additions to ketones that are both general and highly enantioselective. We describe herein a practical catalytic asymmetric addition of ethyl groups to ketones. The catalyst is derived from reaction of camphor sulfonyl chloride and trans-1,2-diaminocyclohexane. The resulting diketone is reduced with NaBH4 to give the C2-symmetric exo diastereomer. Use of this ligand with titanium tetraisopropoxide and dialkylzinc at room temperature results in enantioselective addition of the alkyl group to the ketone. The resulting tertiary alcohols are isolated with high enantiomeric excess (all cases give greater than 87% ee, except one). The reaction has been run with 37 mmol (5 g) 3-methylacetophenone and 2 mol % catalyst to afford 73% yield of the resulting tertiary alcohol with 99% ee.
124 citations
TL;DR: Two reaction manifolds are applicable to various secondary amides and are practical in that the procedures provide the desired secondary or tertiary amine as a single product.
Abstract: A triruthenium cluster, (μ3,η2,η3,η5-acenaphthylene)Ru3(CO)7 (1) catalyzes the reaction of secondary amides with hydrosilanes, yielding a mixture of secondary amines, tertiary amines, and silyl enamines. Production of secondary amines with complete selectivity is achieved by the use of higher concentration of the catalyst (3 mol %) and the use of bifunctional hydrosilanes such as 1,1,3,3-tetramethyldisiloxane. Acidic workup of the reaction mixture affords the corresponding ammonium salts, which can be treated with a base, providing a facile method for isolation of secondary amines with high purity. In contrast, tertiary amines are formed with high selectivity by using lower concentration of the catalyst (1 mol %) and polymeric hydrosiloxanes (PMHS) as reducing agent. Reduction with PMHS encapsulates the ruthenium catalyst and organic byproducts to the insoluble silicone resin. The two reaction manifolds are applicable to various secondary amides and are practical in that the procedures provide the desired...
124 citations