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 synthesis of benzimidazoles and quinoxalines from aromatic diamines and alcohols by iridium-catalyzed acceptorless dehydrogenative alkylation.

Abstract: Benzimidazoles and quinoxalines are important N-heteroaromatics with many applications in pharmaceutical and chemical industry. Here, the synthesis of both classes of compounds starting from aromatic diamines and alcohols (benzimidazoles) or diols (quinoxalines) is reported. The reactions proceed through acceptorless dehydrogenative condensation steps. Water and two equivalents of hydrogen are liberated in the course of the reactions. An Ir complex stabilized by the tridentate P^N^P ligand N(2) ,N(6) -bis(di-isopropylphosphino)pyridine-2,6-diamine revealed the highest catalytic activity for both reactions.

New Iridium Catalysts for the Selective Alkylation of Amines by Alcohols under Mild Conditions and for the Synthesis of Quinolines by Acceptor-less Dehydrogenative Condensation

Abstract: A novel family of iridium catalysts stabilised by P,N-ligands have been introduced. The ligands are based on imidazo[1,5-b]pyridazin-7-amines and can be synthesised with a broad variety of substitution patterns. The catalysts were synthesised quantitatively from the protonated ligands and a commercially available iridium precursor. The catalysts mediate the alkylation of amines by alcohols under mild conditions (70 °C). In addition, the synthesis of quinolines from secondary or primary alcohols and amino alcohols is reported. This sustainable synthesis proceeds through the liberation of two equivalents of water and two equivalents of dihydrogen. The investigations indicate that catalysts suitable for hydrogen autotransfer or borrowing hydrogen chemistry might also be suitable for acceptor-less dehydrogenative condensation reactions.

Nickel-catalyzed allylic defluorinative alkylation of trifluoromethyl alkenes with reductive decarboxylation of redox-active esters

Abstract: Herein, we report a nickel-catalyzed allylic defluorinative alkylation of trifluoromethyl alkenes through reductive decarboxylation of redox-active esters. The present reaction enables the preparation of functionalized gem-difluoroalkenes with the formation of sterically hindered C(sp3)–C(sp3) bonds under very mild reaction conditions, while tolerating many sensitive functional groups and requiring minimal substrate protection. Therefore, this method provides an efficient and convenient approach for late-stage modification of biologically interesting molecules.

[12] Reductive alkylation of lysine residues to alter crystallization properties of proteins.

Abstract: Publisher Summary This chapter discusses the reductive alkylation of lysine residues to alter the crystallization properties of proteins. Chemical modification has played an essential role in the development of protein function. The reductive alkylation of lysine residues involves the initial formation of a Schiff base between the ɛ-amino group of a lysine residue and a ketone or aldehyde that is then reduced to a secondary or tertiary amine. In principle, a wide variety of alkyl moieties can be added to an amino group by reductive alkylation. In practice, the majority of cases employing this chemical modification have focused on adding methyl groups using formaldehyde because of the greater reactivity of formaldehyde than other ketones or aldehydes and because this modification has the mildest effect on the biochemical properties of a protein. The protocols described in the chapter are designed for complete modification of all available lysine residues. Amino acid analysis is the best way of determining the degree of modification of the lysine residues after reductive alkylation. It has the advantage of quantitatively defining the number of non-, mono-, di-, and tri-methylated lysine residues. It reveals the presence of any side reactions with other reactive amino acid side chains in a protein.