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.

Synthesis of novel quaternary amino acids using molybdenum-catalyzed asymmetric allylic alkylation.

Abstract: The Mo-catalyzed asymmetric allylic alkylation using azlactones provides extraordinary levels of selectivity. Thus, a wide range of cinnamyl-type substrates react with 2-methyl and 2-benzyl azlactones to give only the product resulting from attack at the more substituted carbon. Using other alkyl substituents such as 2-methylthioethyl, isobutyl, allyl, and isopropyl provides products that still retain excellent regioselectivity but small quantities of the linear product are also observed. In all cases, excellent diastereo- and enantioselectivity of the branched alkylated product are observed. This new asymmetric reaction provides ready access to unusual quarternary amino acids, important building blocks for biological applications. The reactions complements the Pd AAA wherein the cinnamyl substrate leads to only the product of attack at the primary terminus of the allyl moiety.

Visible‐Light‐Driven Palladium‐Catalyzed Radical Alkylation of C−H Bonds with Unactivated Alkyl Bromides

Abstract: Reported herein is a novel visible-light photoredox system with Pd(PPh3 )4 as the sole catalyst for the realization of the first direct cross-coupling of C(sp3 )-H bonds in N-aryl tetrahydroisoquinolines with unactivated alkyl bromides. Moreover, intra- and intermolecular alkylations of heteroarenes were also developed under mild reaction conditions. A variety of tertiary, secondary, and primary alkyl bromides undergo reaction to generate C(sp3 )-C(sp3 ) and C(sp2 )-C(sp3 ) bonds in moderate to excellent yields. These redox-neutral reactions feature broad substrate scope (>60 examples), good functional-group tolerance, and facile generation of quaternary centers. Mechanistic studies indicate that the simple palladium complex acts as the visible-light photocatalyst and radicals are involved in the process.

Catalytic Asymmetric Friedel-Crafts Alkylations

Abstract: GENERAL ASPECTS AND HISTORICAL BACKGROUND Introduction General Aspects and Historical Background Catalytic Enantioselective FC Reactions: An Introduction MICHAEL ADDITION Chelating Alpha, Beta-Unsaturated Compounds Simple Alpha, Beta-Unsaturated Substrates Nitroalkenes ADDITION TO CARBONYL COMPOUNDS Aldehydes/Ketones Imines NUCLEOPHILIC ALLYLIC ALKYLATION AND HYDROARYLATION OF ALLENES Introduction Allylic Alkylations Metallo-Catalyzed Hydroarylation of Allenes NUCLEOPHILIC SUBSTITUTION ON CSP3 CARBON ATOMS Ring-Opening of Epoxides Direct Activation of Alcohols UNACTIVATED ALKENES Introduction Early Studies Rh(I)-Catalyzed Enantioselective Hydroarylation of Iminoarenes Pt(II)-Catalyzed Enantioselective Hydroarylation of Alkenylidoles Au(II)-Catalyzed Enantioselective Hydroarylation of Allenylindoles Conclusions and Outlook Experimental: Selected Procedures CATALYTIC ASYMMETRIC FRIEDEL-CRAFTS ALKYLATIONS IN TOTAL SYNTHESIS Introduction Total Synthesis of Indole-Containing Compounds Total Synthesis of Pyrrole-Containing Compounds Friedel-Crafts Alkylation of Furan Derivatives in Total Synthesis Friedel-Crafts Alkylation of Arenes in Total Synthesis Asymmetric Synthesis of Natural Products Based on Diastereoselective Friedel-Crafts Reactions INDUSTRIAL FRIEDEL-CRAFTS IN CHEMISTRY Introduction Green Chemistry and the Friedel-Crafts Reaction Heterogeneous Catalysts for the Friedel-Crafts Reaction Large Scale Hydrocarbon Processing Conclusions and Perspectives

Organocalcium-mediated nucleophilic alkylation of benzene

Abstract: The electrophilic aromatic substitution of a C–H bond of benzene is one of the archetypal transformations of organic chemistry. In contrast, the electron-rich π-system of benzene is highly resistant to reactions with electron-rich and negatively charged organic nucleophiles. Here, we report that this previously insurmountable electronic repulsion may be overcome through the use of sufficiently potent organocalcium nucleophiles. Calcium n -alkyl derivatives—synthesized by reaction of ethene, but-1-ene, and hex-1-ene with a dimeric calcium hydride—react with protio and deutero benzene at 60°C through nucleophilic substitution of an aromatic C–D/H bond. These reactions produce the n- alkyl benzenes with regeneration of the calcium hydride. Density functional theory calculations implicate an unstabilized Meisenheimer complex in the C–H activation transition state.