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.

Enzymatic assembly of carbon-carbon bonds via iron-catalysed sp 3 C-H functionalization.

Abstract: Although abundant in organic molecules, carbon–hydrogen (C–H) bonds are typically considered unreactive and unavailable for chemical manipulation. Recent advances in C–H functionalization technology have begun to transform this logic, while emphasizing the importance of and challenges associated with selective alkylation at a sp^3 carbon. Here we describe iron-based catalysts for the enantio-, regio- and chemoselective intermolecular alkylation of sp^3 C–H bonds through carbene C–H insertion. The catalysts, derived from a cytochrome P450 enzyme in which the native cysteine axial ligand has been substituted for serine (cytochrome P411), are fully genetically encoded and produced in bacteria, where they can be tuned by directed evolution for activity and selectivity. That these proteins activate iron, the most abundant transition metal, to perform this chemistry provides a desirable alternative to noble-metal catalysts, which have dominated the field of C–H functionalization. The laboratory-evolved enzymes functionalize diverse substrates containing benzylic, allylic or α-amino C–H bonds with high turnover and excellent selectivity. Furthermore, they have enabled the development of concise routes to several natural products. The use of the native iron-haem cofactor of these enzymes to mediate sp^3 C–H alkylation suggests that diverse haem proteins could serve as potential catalysts for this abiological transformation, and will facilitate the development of new enzymatic C–H functionalization reactions for applications in chemistry and synthetic biology.

Replacing conventional carbon nucleophiles with electrophiles: nickel-catalyzed reductive alkylation of aryl bromides and chlorides

Abstract: A general method is presented for the synthesis of alkylated arenes by the chemoselective combination of two electrophilic carbons Under the optimized conditions, a variety of aryl and vinyl bromides are reductively coupled with alkyl bromides in high yields Under similar conditions, activated aryl chlorides can also be coupled with bromoalkanes The protocols are highly functional-group tolerant (−OH, −NHTs, −OAc, −OTs, −OTf, −COMe, −NHBoc, −NHCbz, −CN, −SO2Me), and the reactions are assembled on the benchtop with no special precautions to exclude air or moisture The reaction displays different chemoselectivity than conventional cross-coupling reactions, such as the Suzuki–Miyaura, Stille, and Hiyama–Denmark reactions Substrates bearing both an electrophilic and nucleophilic carbon result in selective coupling at the electrophilic carbon (R–X) and no reaction at the nucleophilic carbon (R–[M]) for organoboron (−Bpin), organotin (−SnMe3), and organosilicon (−SiMe2OH) containing organic halides (X–R–[M