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Dinitrogen heterocycles are among the most important molecular structures, and the synthesis of these types of structures through intermolecular 1,2-diamination of olefins is a direct and efficient method. However, the types of nitrogen sources are mostly derived from ureas or arylamines, and nitrogen sources from aliphatic amines are still limited due to their distinct electronic and steric effects. Herein, we report a palladium-catalyzed aerobic intermolecular 1,2-diamination of conjugated dienes, using ethanediamine and α-amino amide derivatives as nitrogen sources respectively, for the synthesis of piperazines and 2-piperazinones in good yields (up to 95 %) and with high regio- and chemoselectivities., (© 2022 Wiley-VCH GmbH.)

Amines are widely applied in the chemical and pharmaceutical industries, and the development of synthetic methods for their preparation is driven by their importance. The amination of alkenes is a direct and efficient method for the construction of amines, of which oxidative amination is more valuable because it can give the desired products with greater functionality and flexibility. In oxidative amination, using molecular oxygen (O2) as a terminal oxidant has promising industrial application prospects. In recent years, the palladium‐catalyzed aerobic oxidation of alkenes has seen significant progress, and its related research has also been extended to the aerobic oxidative amination of alkenes. The corresponding oxidation systems have been developed from early research involving the introduction of cocatalysts to the more recent systems which utilize auxiliary ligands instead of cocatalysts. In this review, the advancements in the palladium‐catalyzed aerobic oxidative amination of monoalkenes and conjugated dienes over the last two decades are discussed, with emphasis on aerobic oxidation process and their associated mechanisms. [ABSTRACT FROM AUTHOR]

Dinitrogen heterocycles are among the most important molecular structures, and the synthesis of these types of structures through intermolecular 1,2‐diamination of olefins is a direct and efficient method. However, the types of nitrogen sources are mostly derived from ureas or arylamines, and nitrogen sources from aliphatic amines are still limited due to their distinct electronic and steric effects. Herein, we report a palladium‐catalyzed aerobic intermolecular 1,2‐diamination of conjugated dienes, using ethanediamine and α‐amino amide derivatives as nitrogen sources respectively, for the synthesis of piperazines and 2‐piperazinones in good yields (up to 95 %) and with high regio‐ and chemoselectivities. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Long‐range olefin isomerization could lead to the remote functionalization of hydrocarbon chains, which is advantageous with regards to atom‐, step‐, and redox economy. However, present methodologies for long‐range olefin isomerization are mainly focused on heteroatom directed remote olefin migration; studies using aryl groups as the directing group are limited. The limited examples either utilize aryl olefins with special substituted groups on a benzene ring, or use elaborately optimized ligands or co‐catalysts to accelerate the isomerization. A more simple catalytic system for general aryl olefins, without the need for special ligands or co‐catalysts, was to be developed. Herein, we report a Pd‐catalyzed long‐range olefin isomerization (up to 15 units) for general aryl olefins via a 1,2‐hydrogen shift mechanism. This methodology provides a simple pathway to long‐range olefin isomerization without the participation of special ligands or co‐catalysts. [ABSTRACT FROM AUTHOR]

The first metal-catalyzed oxidative intermolecular 1,4-diamination of conjugated dienes has been developed. A series of medium ring compounds were constructed via palladium-catalyzed intermolecular [4+4] annulations. Oxygen was successfully used as an oxidant instead of the existing stoichiometric metals or hypervalent iodine reagents. 20 examples are reported, and good yields and regioselectivities could be obtained for the majority of diamines and conjugated diene substrates. [ABSTRACT FROM AUTHOR]

A method for the preparation of indolines via palladium-catalyzed aerobic intramolecular allylic C H activation was developed. Oxygen was successfully used as oxidant with catalytic amount of 1,4-benzoquinone. 16 examples were reported, the majority of substrates gave moderate to good yields. [ABSTRACT FROM AUTHOR]

A Pd(II)-catalyzed oxidative cyclization of olefinic tosylamides was developed for the preparation of aryl-fused and N-containing six-membered heterocycles. Under optimized conditions the reaction proceeded with high activity and selectivity, with yields of up to 83% being obtained. This procedure provides a facile and efficient route to the aforementioned heterocycles with 2-acetoxy functionality. [ABSTRACT FROM AUTHOR]

Vinylaziridines are important building blocks in organic chemistry, especially in the synthesis of nitrogen‐containing heterocycles. The direct and efficient transfer of an appropriate nitrogen source to readily accessible conjugated dienes is a notable methodology. The Pd‐catalyzed oxidative 1,2‐difunctionalization of conjugated dienes through a π‐allyl‐palladium species should be an ideal method for the selective synthesis of vinylaziridines. However, this method faces the challenge of regioselectivity, often resulting in 1,4‐difunctionalization instead. In this study, we developed a Pd‐catalyzed aerobic 1,2‐difunctionalization of conjugated dienes via a π‐allyl‐palladium species to achieve regio‐, site‐ and stereo‐selective aziridination under the synergistic effects of PdII, CuI, I−, and O2. The π‐allyl palladium species formed in the system undergoes an unusual iodination process, leading to the formation of an allyl iodide intermediate. Subsequently, the vinylaziridine is obtained through intramolecular SN2′ substitution of the allyl iodide. [ABSTRACT FROM AUTHOR]

Abstract: This article describes an efficient method for the preparation of chiral chroman derivatives by the Pd(II)-catalyzed asymmetric Wacker-type cyclization using a chelation-induced axially chiral tetraoxazoline ligand. Under the optimized conditions, up to 80% yield and up to 92% ee were obtained. This is the first example to utilize o-trisubstituted 3-butenylphenols as substrates in such transformation. [Copyright &y& Elsevier]