Palladium-Catalyzed Oxidative Amination of Alkenes:  Improved Catalyst Reoxidation Enables the Use of Alkene as the Limiting Reagent

Abstract

Palladium-catalyzed methods for intermolecular aerobic oxidative amination of alkenes have been identified that are compatible with the use of alkene as the limiting reagent. These procedures, which enhance the utility of this reaction with alkenes that are not commercially available, are demonstrated with substrates bearing dialkyl ether, carboxyester, epoxide, and silyl ether groups.

PdII‐Catalyzed Monoselective ortho Halogenation of CH Bonds Assisted by Counter Cations: A Complementary Method to Directed ortho Lithiation

“…However, we were pleased to find that tetraalkyl ammonium salts not only promote the C À H insertion in the absence of another base, but also drastically improve the monoselectivity (Table 4, entries [1][2][3][4]. [18][19][20] A significant improvement in monoselectivity in favor of the less-hindered ortho position was also observed with substrates 22, 24, and 25. The lower monoselectivity with substrates 13 and 23 is most likely a result of noncatalyzed electrophilic iodination of the electron-rich arenes.…”

“…The proposed catalytic cycle in Scheme 2 shows the role of the tetraalkyl ammonium salt. The formation of an ion pair is crucial for the reaction, [18][19][20] although it is not clear at this stage whether the Pd II center initiates the CÀH cleavage by coordinating with the lone pair of the carbonyl group or simply by displacing the ammonium cation to form a Pd carboxylate. Both pathways would lead to the formation of the same intermediate B.…”

Palladium-Catalyzed Intermolecular Oxidative Amination of Alkenes with Amines, Using Molecular Oxygen as Terminal Oxidant

“…Although significant developments in aza-Wacker-type reactions have been achieved, the existing aza-Wacker process generally requires non-basic nitrogen nucleophiles such as carboxamides, carbamates, and sulfonamides as amination reagents, under relatively high oxygen pressures (4-10 atm.) or in the presence of an external oxidant source such as benzoquinone (BQ), PhBQ, PhI(OAc) 2 , or PhI(OPiv) 2 [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]. In contrast, the oxidative amination of olefins using more basic, simple amines as substrates has been less explored, and is generally limited to intramolecular reactions [34][35][36][37][38], because of the strong coordination of amines to Pd, which results in catalyst deactivation.…”

Palladium‐Catalyzed Intermolecular Aerobic Oxidative Amination of Terminal Alkenes: Efficient Synthesis of Linear Allylamine Derivatives

“…[4][5][6] Palladium-catalyzed methods for intermolecular aerobic oxidative amination of unactivated olefins, known as azaWacker reactions, have been recently reported to yield enamide derivatives (Scheme 1, left arrow).[2e, 4, 6] These reactions are proposed to proceed by Markovnikov aminopalladation of the alkene with subsequent bhydride elimination, resulting in the functionalization of the olefin at the C2 position. Herein we describe a new method for intermolecular dioxygen-coupled oxidative amination of unactivated olefins under cocatalyst free reaction conditions, which affords linear allylic amine derivatives with high regioselectivity (Scheme 1, right arrow).…”