Project description:The hydrofunctionalization of alkenes, explored for over 100 years, offers the potential for a direct, atom-economical approach to value-added products. While thermodynamically favored, the kinetic barrier to such processes necessitates the use of catalysts to control selectivity and reactivity. Modern variants typically rely on noble metals that require different ligands for each class of hydrofunctionalization, thereby limiting generality. This Letter describes a general iron-based system that catalyzes the hydroamination and hydroetherification of simple unactivated olefins.

| S-EPMC6583794 | biostudies-literature

Rhodium-Catalyzed Asymmetric Hydroamination of Allyl Amines.

Project description:A Rh-catalyzed enantioselective hydroamination of allylamines using a chiral BIPHEP-type ligand is reported. Enantioenriched 1,2-diamines are formed in good yields and with excellent enantioselectivities. A diverse array of nucleophiles and amine directing groups are demonstrated, including deprotectable motifs. Finally, the methodology was demonstrated toward the rapid synthesis of 2-methyl-moclobemide.

| S-EPMC6693864 | biostudies-literature

Rhodium-catalyzed asymmetric hydroamination and hydroindolation of keto-vinylidenecyclopropanes.

Project description:We reported a highly regio- and enantioselective hydroamination and hydroindolation of keto-vinylidenecyclopropanes via cationic Rh(i) catalysis in this context. The combination of various secondary amines and indoles with keto-vinylidenecyclopropanes afforded the corresponding hydrofunctionalization products in good to excellent yields with outstanding ee values under mild conditions. A new TMM-Rh model complex was proposed, providing an atom economical Rh-π-allyl precursor at the same time. Moreover, the resulting products could easily be transformed into more complex polyheterocycles upon further synthetic manipulation.

| S-EPMC5994874 | biostudies-literature

Enantioselective Rhodium(III)-Catalyzed Markovnikov Hydroboration of Unactivated Terminal Alkenes.

Project description:We report the first enantioselective Rh-catalyzed Markovnikov hydroboration of unactivated terminal alkenes. Using a novel sp2-sp3 hybridized diboron reagent and water as a proton source, a broad range of alkenes undergo hydroboration to provide secondary boronic esters with high regio- and enantiocontrol.

| S-EPMC5515510 | biostudies-literature

Enantioselective hydroamination of unactivated terminal alkenes.

Project description:Asymmetric alkene hydroamination could be a direct route to valuable chiral amines from abundant feedstocks. However, most asymmetric hydroaminations have limited synthetic value because they require a large excess of alkene, occur with modest enantioselectivity, and proceed with limited tolerance of functional groups. We report an enantioselective, intermolecular hydroamination of unactivated terminal alkenes that occurs with equimolar amounts of alkene and amine, tolerates many functional groups, and occurs in high yield, with high enantioselectivity and turnover numbers. Mechanistic studies revealed factors, including reversibility of the addition, reversible oxidation of the product amine, competing isomerization of the alkene reactant, and unfavorable replacement of sacrificial ligands in standard catalyst precursors by the chiral bisphosphine, that needed to be addressed to achieve enantioselective N-H additions to alkenes.

| S-EPMC9140304 | biostudies-literature

Rhodium(III)-Catalyzed Three-Component 1,2-Diamination of Unactivated Terminal Alkenes.

Project description:We report a three-component diamination of simple unactivated alkenes using an electrophilic nitrene source and amine nucleophiles. The reaction provides rapid access to 1,2-vicinal diamines from terminal alkenes through a one-pot protocol. The transformation proceeds smoothly with excellent tolerance for a broad array of primary and secondary amines, affording the desired product with good yield and regioselectivity. The mechanism is proposed to proceed through a Rh(III)-catalyzed aziridination of alkenes with subsequent ring opening by primary or secondary amines.

| S-EPMC8290961 | biostudies-literature

Nickel-catalyzed asymmetric reductive aryl-allylation of unactivated alkenes.

Project description:Herein we report a nickel-catalyzed asymmetric reductive aryl-allylation of aryl iodide-tethered unactivated alkenes, wherein both acyclic allyl carbonates and cyclic vinyl ethylene carbonates can serve as the coupling partners. Furthermore, the direct use of allylic alcohols as the electrophilic allyl source in this reaction is also viable in the presence of BOC anhydride. Remarkably, this reaction proceeds with high linear/branched-, E/Z- and enantio-selectivity, allowing the synthesis of various chiral indanes and dihydrobenzofurans (50 examples) containing a homoallyl-substituted quaternary stereocenter with high optical purity (90-98% ee). In this reductive reaction, the use of pregenerated organometallics can be circumvented, giving this process good functionality tolerance and high step-economy.

| S-EPMC8133004 | biostudies-literature

Enantioselective, Aerobic Copper-Catalyzed Intramolecular Carboamination and Carboetherification of Unactivated Alkenes.

Project description:Reduction of waste is an important goal of modern organic synthesis. We report herein oxidase reactivity for enantioselective intramolecular copper-catalyzed alkene carboamination and carboetherification reactions where previously used stoichiometric MnO2 has been replaced with oxygen. This substitution was risky as the reaction mechanism is thought to involve C-C bond formation via addition of alkyl carbon radicals to arenes. Such intermediates are also susceptible to C-O bond formation via O2 addition. Control of absolute stereochemistry under aerobic conditions was also uncertain. The oxidative cyclization efficiencies appear to track with the ease of the radical addition to the arenes.

| S-EPMC8293922 | biostudies-literature

Intramolecular hydroamination of unbiased and functionalized primary aminoalkenes catalyzed by a rhodium aminophosphine complex.

Project description:We report a rhodium catalyst that exhibits high reactivity for the hydroamination of primary aminoalkenes that are unbiased toward cyclization and that possess functional groups incompatible with more electrophilic hydroamination catalysts. The rhodium catalyst contains an unusual diaminophosphine ligand (L1) that binds to rhodium in a κ(3)-P,O,P mode. The reactions catalyzed by this complex typically proceed at mild temperatures (room temperature to 70 °C) and occur with primary aminoalkenes lacking substituents on the alkyl chain that bias the system toward cyclization, with primary aminoalkenes containing chloride, ester, ether, enolizable ketone, nitrile, and unprotected alcohol functionality, and with primary aminoalkenes containing internal olefins. Mechanistic data imply that these reactions occur with a turnover-limiting step that is different from that of reactions catalyzed by late-transition-metal complexes of Pd, Pt, and Ir. This change in the turnover-limiting step and resulting high activity of the catalyst stem from favorable relative rates for protonolysis of the M-C bond to release the hydroamination product versus reversion of the aminoalkyl intermediate to regenerate the acyclic precursor. Probes of the origin of the reactivity of the rhodium complex of L1 imply that the aminophosphine groups lead to these favorable rates by effects beyond steric demands and simple electron donation to the metal center.

| S-EPMC2948069 | biostudies-literature

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