The addition of an N-H bond to an olefin is the most direct route for the synthesis of alkylamines. Currently, intermolecular hydroamination is limited to reactions of a narrow range of reagents containing N-H bonds or activated alkenes, and all the examples of additions to unactivated alkenes require large excesses of alkene. We report intermolecular hydroamination reactions of indoles with unactivated olefins. The reactions occur with as few as 1.5 equiv of olefin to form N-alkylindoles exclusively and in good yield. Characterizations of the catalyst resting state, kinetic data, labeling studies, and computational data imply that the addition occurs by olefin insertion into the Ir-N bond of an N-indolyl complex and that this insertion reaction is faster than insertion of olefin into the Ir-C bond of the isomeric C-2-indolyl complex.
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http://dx.doi.org/10.1021/ja412116d | DOI Listing |
Org Biomol Chem
December 2024
School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, P. R. China.
Herein, we report a novel Al compound supported by a NacNac ligand that facilitates the anti-Markovnikov hydroamination of aromatic alkenes and primary amines. This represents the first instance of an aluminum-catalyzed intermolecular hydroamination of alkenes, successfully synthesizing a variety of aromatic imine derivatives. The proposed mechanism suggests that the coordination activation of BuOK by ether solvents is crucial, allowing the BuO anion to coordinate with the catalyst's Al center, thus forming a key intermediate.
View Article and Find Full Text PDFJ Mol Model
December 2024
College of Chemistry and Material Science, Shandong Agricultural University, Taian, Shandong, 271018, People's Republic of China.
Context: Nickel-catalyzed hydroamination of dienes with phenylmethanamines was studied theoretically to investigate reaction mechanism. These calculated results revealed that Ni-catalyzed hydroamination began with the O - H bond activation of trifluoroethanol, including three important elementary steps: the ligand-to-ligand hydrogen migration, the nucleophilic attack of phenylmethanamine, and hydrogen migration. The nucleophilic attack of phenylmethanamine was the rate-determining step, and the branched product of 3,4-addition with (S)-chirality was the most dominant.
View Article and Find Full Text PDFChem Commun (Camb)
December 2024
College of Chemistry and Pharmaceutical Engineering, Nanyang Normal University, Nanyang 473061, China.
A palladium-catalyzed divergent reaction of primary benzamides using norbornene (NBE) derivatives as a controlled switch is reported. When NBE is used as a mediator, indanones are synthesized with moderate to good yields a Catellani reaction that involves sequential -C-H alkylation and -C-N bond cleavage annulation of primary benzamides. Employing norbornadiene (NBD) instead of NBE enables the assembly of -alkylamines by an intermolecular hydroamination reaction.
View Article and Find Full Text PDFOrg Lett
November 2024
Key Laboratory for Green Organic Synthesis and Application of Hunan Province, Key Laboratory of Environmentally Friendly Chemistry and Application of Ministry of Education, College of Chemistry, Xiangtan University, Xiangtan, 411105, China.
A visible-light induced intermolecular hydroamination of alkenes with azoles is reported, delivering pharmaceutically valuable N-benzyl azoles in high yields with excellent Markovnikov selectivity. Mechanistic studies suggest that the process is initiated by the energy transfer of the excited photocatalyst with alkenes, followed by the single electron reduction, protonation, and subsequent single electron oxidation to afford the key alkyl carbocation intermediate. This protocol exhibits advantages of broad functional group tolerance, excellent atom economy, high efficiency, and mild reaction conditions.
View Article and Find Full Text PDFChem Commun (Camb)
November 2024
TUM School of Natural Sciences, Department of Chemistry, Catalysis Research Center and Wacker-Institute of Silicon Chemsitry, Technische Universität München (TUM), Lichtenbergstrasse 4, 85748 Garching bei München, Germany.
Herein, we report the reactivity of N-heterocyclic carbene stabilized silylene-phosphinidene IDippPSi(TMS)SiTol (IDipp = 1,3-bis(2,6-diisopropylphenyl)-imidazolin-2-ylidene) with ammonia, which results in an intermolecular 1,5-hydroamination and dearomatization of the NHC wingtip. DFT calculations reveal an unprecedented mechanism involving ammonia coordination to the silicon center, Meisenheimer-type complex formation, and a proton abstraction by the dearomatized aryl moiety.
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