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.

The Nickel/Copper-Catalyzed Direct Alkylation of Heterocyclic C—H Bonds

Abstract: A general and straightforward protocol for the cross-coupling of non-activated alkyl halides with heterocyclic CH bonds has been developed. The transformation is chemo- and regioselective and many functional groups on both coupling partners are tolerated. The method employs cheap nickel/copper catalysts, and expands significantly the scope of CH functionalization.

Asymmetric Friedel-Crafts alkylation of pyrroles with nitroalkenes using a dinuclear zinc catalyst.

Abstract: The catalytic enantioselective and atom economic Friedel−Crafts alkylation of pyrroles with nitroalkenes under mild reaction conditions using a dinuclear zinc catalyst is reported. The versatility of the reaction is demonstrated by the conversion of a number of differentially substituted nitroalkenes with differentially substituted pyrroles. Tandem addition reactions to form 2,5-disubstituted pyrroles are also demsonstrated. All pyrrole alkylations have been carried out without using N-protecting groups, which also enhances the efficiency by which substituted pyrroles may be synthesized. The reactions result in good yields and excellent enantioselectivities.

Total synthesis of (+)-lithospermic acid by asymmetric intramolecular alkylation via catalytic C-H bond activation.

Abstract: The total synthesis of (+)-lithospermic acid is described The efficient synthesis features an asymmetric alkylation via C−H bond activation to assemble the dihydrobenzofuran core of the natural product This was accomplished via a chiral imine-directed C−H bond functionalization and represents the first application of this C−H activation method to natural product synthesis Furthermore, a challenging deprotection of a late-stage permethylated lithospermic acid was achieved

Highly enantioselective Friedel-Crafts alkylations of pyrroles and indoles with alpha'-hydroxy enones under Cu(II)-simple bis(oxazoline) catalysis.

Abstract: Remarkably high and regular enantioselectivities are obtained in Friedel-Crafts alkylation reactions involving alpha'-hydroxy enone templates and Cu(II)-bis(oxazoline) complexes as catalysts The simple elaboration of adducts provides a route to enantioenriched aldehydes, carboxylic acids, and ketones containing the pyrrole and indole frameworks

An Efficient Method for the Selective Iridium-Catalyzed Monoalkylation of (Hetero)aromatic Amines with Primary Alcohols

Abstract: An efficient multi-gram scale synthesis protocol of a variety of P,N ligands is described. The synthesis is achieved in a two-step reaction. First, the amine is deprotonated and subsequently the chlorophosphine is added to yield the corresponding P,N ligand. Deprotonation of the amine is normally achieved with n-BuLi at low temperature, but for the preparation of ligands with a 2,2′-dipyridylamino backbone and phosphines with a high steric demand KH has to be employed in combination with reaction temperatures of 110 °C for the salt metathesis step. The reaction of two equivalents of a selected P,N ligand with one equivalent of the iridium complex [IrCl(cod)]2 (cod=1,5-cyclooctadiene) affords P,N ligand-coordinated iridium complexes in quantitative yield. X-Ray single crystal structure analysis of one of these complexes reveals a monomeric five-coordinated structure in the solid state. The iridium complexes were used to form catalysts for the N-alkylation of aromatic amines with alcohols. The catalyst system was optimized by studying 8 different P,N ligands, 9 different solvents and 14 different bases. Systematic variation of the substrate to base and the amine to alcohol ratios as well as the catalyst loading led to optimized catalytic reaction conditions. The substrate scope of the developed catalytic protocol was shown by synthesizing 20 different amines of which 12 could be obtained in isolated yields higher than 90%. A new efficient catalyst system for the selective monoalkylation of primary aromatic and heteroaromatic amines with primary aromatic, heteroaromatic as well as aliphatic alcohols has been established. The reaction proceeds with rather moderate catalyst loadings.