Hydroamination Of Alkenes Research Articles

Formaldehyde as Tethering Organocatalyst: Highly Diastereoselective Hydroaminations of Allylic Amines.

Catalysts possessing sufficient activity to achieve intermolecular alkene hydroaminations under mild conditions are rare, and this likely accounts for the scarcity of asymmetric variants of this reaction. Herein, highly diastereoselective hydroaminations of allylic amines utilizing hydroxylamines as reagents and formaldehyde as catalyst are reported. This catalyst induces temporary intramolecularity, which results in high rate accelerations, and high diastereocontrol with either chiral allylic amines or chiral hydroxylamines. The reaction scope includes internal alkenes. Overall this work provides a new, stereocontrolled route to form complex vicinal diamines.

Hydroaminations of alkenes: a radical, revised, and expanded version.

Radical changes: The applicability of alkene hydroamination has recently been significantly expanded by the development of radical variants that are based on initial hydrogen atom transfer to the alkene. This Highlight assesses the current state of the art, focusing on an iron-catalyzed reaction that utilizes stable nitroarenes as the electrophilic N component and is based on the dual catalytic activation of both starting materials.

Well-Defined Noble Metal Single Sites in Zeolites as an Alternative to Catalysis by Insoluble Metal Salts.

Insoluble precious metal chlorides in polymeric form (i.e., PtCl2, PdCl2, AuCl, RhCl3) are commonly used as catalysts for a plethora of organic reactions in solution. Here we show that only the minor soluble fraction of these precious metal chlorides (typically 5-30%) is catalytically active for the hydroamination, hydroalkoxylation, hydrosilylation, and cycloisomerization of alkynes and alkenes, and that the resting insoluble metal is catalytically useless. To circumvent this waste of precious metal and follow a rational design, we generate here well-dispersed Pt(II) and Pd(II) single sites on zeolite Y, with an exquisite control of the Lewis acidity, to catalyze different hydroaddition reactions to alkynes and alkenes with up to 10(4) catalytic cycles (at least 2 orders of magnitude superior to precious metal chlorides) and with high isolated yields (82-99%, >15 examples).

ChemInform Abstract: Practical Olefin Hydroamination with Nitroarenes.

AbstractAn operationally simple radical hydroamination of olefins with nitro(hetero)arenes is presented, giving access even to hindered amines.

Formal Hydroamination of Alkenes with Nitro- and Heteroarenes

Formal Hydroamination of Alkenes with Nitro- and Heteroarenes

A New N‐Trityl‐Substituted Aminopyridinato Titanium Catalyst for Hydroamination and Hydroaminoalkylation Reactions – Unexpected Intramolecular C–H Bond Activation

AbstractSterically demanding 2,6‐bis(tritylamino)pyridine is used for the synthesis of a mono(2,6‐diaminopyridinato) titanium complex that undergoes unexpected intramolecular C–H bond activation to give access to an unusual 1‐titanaisoindoline derivative. Both titanium complexes do not show high catalytic activity for hydroaminoalkylation reactions of alkenes but exceptional results are obtained in the field of alkene, alkyne, and allene hydroamination including room temperature activity for intramolecular alkene hydroamination, excellent regioselectivity of intermolecular alkyne and allene hydroamination as well as selectivity for hydroamination over hydroaminoalkylation during cyclization reactions of primary aminoalkenes.

Design of Modified Amine Transfer Reagents Allows the Synthesis of α-Chiral Secondary Amines via CuH-Catalyzed Hydroamination.

The CuH-catalyzed hydroamination of alkenes and alkynes using a silane and an amine transfer reagent represents a simple strategy to access chiral amine products. We have recently reported methods to prepare chiral amines with high efficiency and stereoselectivity using this approach. However, the current technology is limited to the synthesis of trialkylamines from dialkylamine transfer reagents (R2NOBz). When monoalkylamine transfer reagents [RN(H)OBz] were used for the synthesis of chiral secondary amines, competitive, nonproductive consumption of these reagents by the CuH species resulted in poor yields. In this paper, we report the design of a modified type of amine transfer reagent that addresses this limitation. This effort has enabled us to develop a CuH-catalyzed synthesis of chiral secondary amines using a variety of amine coupling partners, including those derived from amino acid esters, carbohydrates, and steroids. Mechanistic investigations indicated that the modified amine transfer reagents are less susceptible to direct reaction with CuH.

The effect of hydrogen bond on Brønsted acid-catalyzed intramolecular hydroamination of unfunctionalized olefins

The catalytic activity of benzoic acid could be increased by introducing a hydrogen bond donor group at the ortho-position. Preliminary DFT calculation indicated that the activation of CC double bond was realized by the action of both the carboxyl group and the hydrogen bond donor. The amino group was brought to the activated CC bond by the interaction between the carboxyl oxygen and amino proton. This interaction also increased the nucleophilicity of the amino group. Thus, in the presence of 20 mol % of 2-(trifluoromethanesulfonamido)benzoic acid, intramolecular hydroamination of unfunctionalized olefins gave the corresponding products in up to 95% isolated yields.

ChemInform Abstract: Synthetic Efforts Toward the Lycopodium Alkaloids Inspires a Hydrogen Iodide Mediated Method for the Hydroamination and Hydroetherification of Olefins.

AbstractThe synthesis of the tricyclus (VI), which is a useful precursor for the preparation of Lycopodium alkaloids involves a Diels—Alder cycloaddition and the cyclization of amine (V) as the key steps.

ChemInform Abstract: Formal Intermolecular Hydroamination of Unbiased Olefins for Primary Amine Formation.

A Pd/Ir dual metal tandem catalyst system was found to be active in catalyzing the one-pot, two-step formal hydroamination of unbiased olefins such as 1-dodecene with an ammonia source to give branched primary amines in high yields of >85 % by using only 1 mol-% of the Ir catalyst. This is the first report of the formal one-pot intermolecular hydroamination of olefins to obtain primary amines.

Brønsted Acid Catalyzed Asymmetric Hydroamination of Alkenes: Synthesis of Pyrrolidines Bearing a Tetrasubstituted Carbon Stereocenter

AbstractThe first highly enantioselective Brønsted acid catalyzed intramolecular hydroamination of alkenes enables the efficient construction of a series of chiral (spirocyclic) pyrrolidines with an α‐tetrasubstituted carbon stereocenter with excellent functional group tolerance. A unique feature of this strategy is the use of a thiourea group acting as both the activating and the directing group through cooperative multiple hydrogen bonding with a Brønsted acid and the double bond. The utility of this method is highlighted by the facile construction of chiral synthetic intermediates and important structural motifs that are widely found in organic synthesis.

Brønsted Acid Catalyzed Asymmetric Hydroamination of Alkenes: Synthesis of Pyrrolidines Bearing a Tetrasubstituted Carbon Stereocenter.

The first highly enantioselective Brønsted acid catalyzed intramolecular hydroamination of alkenes enables the efficient construction of a series of chiral (spirocyclic) pyrrolidines with an α-tetrasubstituted carbon stereocenter with excellent functional group tolerance. A unique feature of this strategy is the use of a thiourea group acting as both the activating and the directing group through cooperative multiple hydrogen bonding with a Brønsted acid and the double bond. The utility of this method is highlighted by the facile construction of chiral synthetic intermediates and important structural motifs that are widely found in organic synthesis.

ChemInform Abstract: Heavier Alkaline Earth Catalyzed Ene‐yne Cyclizations: Atom‐Efficient Access to Tetrahydroisoquinoline Frameworks.

AbstractIntermolecular alkene hydroamination may be coupled with intramolecular alkyne hydroamination, catalyzed by inexpensive and abundant alkaline earth precatalysts to provide entry to a variety of tetrahydroisoquinoline frameworks.

Expanding the Forefront of Strong Organic Brønsted Acids: Proton-Catalyzed Hydroamination of Unactivated Alkenes and Activation of Au(I) for Alkyne Hydroamination

The synthesis of a solid, bench-stable, strong organic Brønsted acid with a computed pKa of 0.9 is reported. An X-ray crystal structure and DFT calculations are provided which offer insight into the bonding of this acid. The application of this strong organic Brønsted acid as a catalyst for the intermolecular hydroamination of unactivated alkenes and as an activator for Au(I)-catalyzed alkyne hydroamination with anilines is described.

ChemInform Abstract: Catalytic Hydroamination of Unactivated Olefins Using a Co Catalyst for Complex Molecule Synthesis.

Functional group tolerance is one of the important requirements for chemical reactions, especially for the synthesis of complex molecules. Herein, we report a mild, general, and functional group tolerant intramolecular hydroamination of unactivated olefins using a Co(salen) complex, an N-fluoropyridinium salt, and a disiloxane reagent. This method, which was carried out at room temperature (or 0 °C), afforded three-, five-, six-, and seven-membered ring nitrogen-containing heterocyclic compounds and was compatible with diverse functional groups.

ChemInform Abstract: Enantioselective Intramolecular Hydroamination of Unactivated Alkenes Catalyzed by Mono‐ and Bis(gold) Phosphine Complexes.

AbstractThe title process allows the cyclization of unactivated alkenes with carbamates and ureas to form pyrrolidine derivatives with enantioselectivities up to 85%.

ChemInform Abstract: Catalytic Olefin Hydroamination with Aminium Radical Cations: A Photoredox Method for Direct C—N Bond Formation.

While olefin amination with aminium radical cations is a classical method for C–N bond formation, catalytic variants that utilize simple 2° amine precursors remain largely undeveloped. Herein we report a new visible-light photoredox protocol for the intramolecular anti-Markovnikov hydroamination of aryl olefins that proceeds through catalytically generated aminium radical intermediates. Mechanistic studies are consistent with a process involving amine oxidation via electron transfer, turnover-limiting C–N bond formation, and a second electron transfer step to reduce a carbon-centered radical, rendering the overall process redox-neutral. A range of structurally diverse N-aryl heterocycles can be prepared in good to excellent yields under conditions significantly milder than those required by conventional aminium-based protocols.

Synthetic efforts toward the Lycopodium alkaloids inspires a hydrogen iodide mediated method for the hydroamination and hydroetherification of olefins.

Progress toward the total syntheses of a diverse set of fawcettimine-type Lycopodium alkaloids via a "Heathcock-type" 6-5-9 tricycle is disclosed. This route features an intermolecular Diels-Alder cycloaddition to rapidly furnish the 6-5-fused bicycle and a highly chemoselective directed hydrogenation to build the azonane fragment. While conducting these synthetic studies, trimethylsilyl iodide was found to effect a hydroamination reaction to furnish the tetracyclic core of serratine and related natural products. This observation has been expanded into a general method for the room temperature hydroamination of unactivated olefins with tosylamides utilizing catalytic "anhydrous" HI (generated in situ from trimethylsilyl iodide and water). The presence of the iodide anion is critical to the success of this Brønsted acid catalyzed protocol, possibly due to its function as a weakly coordinating anion. These conditions also effect the analogous hydroetherification reaction of alcohols with unactivated olefins.

Formal Intermolecular Hydroamination of Unbiased Olefins for Primary Amine Formation

AbstractA Pd/Ir dual metal tandem catalyst system was found to be active in catalyzing the one‐pot, two‐step formal hydroamination of unbiased olefins such as 1‐dodecene with an ammonia source to give branched primary amines in high yields of >85 % by using only 1 mol‐% of the Ir catalyst. This is the first report of the formal one‐pot intermolecular hydroamination of olefins to obtain primary amines.

Ruthenium diphosphine complexes as an efficient hydroamination catalyst

Ruthenium-catalyzed hydroamination of alkenes and alkynes with substituted anilines in the presence of various phosphine ligands have been investigated and catalyst activity and selectivity is improved. Ruthenium(II) complexes of diphenylphosphinomethane, diphenylphosphinoethane, diphenylphosphinopropane, diphenylphosphinobutane and diphenylphosphinopentane showed 50–90 % conversion under mild conditions. The effect of diphosphine ligands, substituent groups on anilines and reaction condition on the selectivity of hydroamination reaction were studied and the possible reaction mechanism was discussed. The reaction products were monitored by GC–MS and a mechanism for the hydroamination of alkenes and alkynes by ruthenium diphosphine complexes was proposed and discussed. The structures of two new complexes, C49H58Cl4P2Ru2 and C35H36Cl2P2Ru, as hydroamination catalysts were determined by X-ray crystallography.