Enabling Reductive C–N Cross-Coupling of Nitroalkanes and Boronic Acids by Steric Design of P(III)/P(V)═O Catalysts

Li, Gen; Kanda, Yuzuru; Hong, Sung You; Radosevich, Alexander T.

doi:10.1021/jacs.2c01487

Cited by 26 publications

(12 citation statements)

References 40 publications

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“…Note that the N–Me bond cleavage seems difficult. Although previous studies have attempted to explain the activity of 1PO in various reactions, the reaction mechanism of 1PO -mediated N–N reductive coupling remains unclear.…”

Section: Introductionmentioning

confidence: 99%

N–N Bond Formation by a Small-Ring Phosphine Catalyst via the P^III/P^V Cycle: Mechanistic Study and Guidelines to Obtain a Good Catalyst

Zhang

Sakaki

et al. 2023

ACS Catal.

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The mechanism of the N–N cross-coupling of nitroarene and aniline catalyzed by 1,2,2,3,4,4-hexamethylphosphetane oxide (1PO) as well as the prediction of a better catalyst was theoretically investigated using DFT and DLPNO-CCSD(T) calculations. An active species 1P is generated through deoxygenation of 1PO by diphenylsilane. Then, 1P extracts one oxygen atom from nitroarene to produce nitrosoarene. In this deoxygenation step, the [3 + 1] cheletropic addition is a rate-determining step with the ΔG 0≠ and ΔG 0 values of 28.8 and −7.3 kcal/mol, respectively. Next, nitrosoarene exclusively undergoes a dehydrative condensation reaction with aniline to form an azo-cation intermediate, which is the origin of the high selectivity in this cross-coupling reaction. In this step, 2,4,6-trimethylbenzoic acid plays an essential role to significantly reduce the ΔG 0≠ value from 41.1 to 14.8 kcal/mol. Subsequently, 1P reacts with the azo cation to form a stable hydrazinylphosphonium species through the nucleophilic attack of the phosphorus atom to the cationic nitrogen atom. The phosphonium center preferably accepts a hydroxyl group from water to ensure the formation of hydrazine in the subsequent step. In the [3 + 1] cheletropic addition step, the highest occupied molecular orbital (HOMO) of 1P plays an important role. The small-ring scaffold of 1P raises the HOMO energy compared to acyclic phosphorus compounds to achieve high activity of 1P. Substitution of a dimethylamino group for the methyl group in 1P was theoretically predicted to improve the activity by further increasing the HOMO energy.

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Section: Introductionmentioning

confidence: 99%

N–N Bond Formation by a Small-Ring Phosphine Catalyst via the P^III/P^V Cycle: Mechanistic Study and Guidelines to Obtain a Good Catalyst

Zhang

Sakaki

et al. 2023

ACS Catal.

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“…[25,26] Given their prevalence as inexpensive and readily available feedstocks, the development of innovative methodologies employing nitroarenes as the direct nitrogen source is of particular importance. [27,28] A number of reports exploring the reactivity of nitroarenes has been disclosed in recent years, for example, molybdenum, copper or P III /P V -catalyzed system for the reductive CÀ N cross-coupling of nitroarenes with arylboronic acids, [29][30][31][32][33][34][35][36][37] nickel-or manganese-catalysed amidation and amination, [38][39][40][41][42][43] iron-catalyzed olefin hydroamination, [44] electrophilic amination with organozinc compounds, [45] showcasing the potential for exploiting nitroarene compounds as simple precursors for the design of new atom-, step-and redoxeconomical reactions to form value-added products.…”

Section: Introductionmentioning

confidence: 99%

Direct Synthesis of Unprotected Indolines Through Intramolecular sp³ C−H Amination Using Nitroarenes as Aryl Nitrene Precursors

Sirvinskaite,

Nardo,

Müller

et al. 2023

Chemistry A European J

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Given the prevalence of molecules containing nitro groups in organic synthesis, innovative methods to expand the reactivity of this functional group are of interest in both industrial and academic settings. In this report, a metal‐free intramolecular benzylic sp3 C–H amination is disclosed using aryl nitro compounds as aryl nitrene precursors. Organosilicon reagent N,N’‐bis(trimethylsilyl)‐4,4’‐bipyridinylidene (Si‐DHBP) served as an efficient reductant in the transformation, enabling the in situ generation of aryl nitrene species for the direct, metal‐free synthesis of unprotected 2‐arylindolines from the corresponding nitroarene compounds.

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“…Phosphines (P(III)) are ubiquitous as ligands for catalysts − and as catalysts themselves. − In an example of the latter, Stephan has demonstrated the utility of phosphonium cations, P(V), in the catalytic initiation of the hydrosilylation of ketones. − Exciting examples out of the Radosevich group demonstrate that a P(III)/P(V) redox cycle can be harnessed to accelerate novel reactions. − Both the Lewis basic properties of P(III) and the Lewis acidic properties of P(V) are demonstrably key components of frustrated Lewis pair chemistry. − Their broad utility make phosphine catalysis a rich area of research.…”

Section: Introductionmentioning

confidence: 99%

Iodenium or Phosphonium: The Ambi-Valent Character of Iodophosphonium Complexes

et al. 2022

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The ambi-valent character of the P–I bond in iodophosphonium complexes ensures that it can be electrophilic at either P or I. Herein, we use an ensemble of computational tools and methodologies to probe the nature of this ambi-valent bond. Geometric and atomic electron population analyses yielded strong trends between the electron donating ability of the phosphine and the strength and polarity of the P–I bond. Quasi-atomic orbital analysis demonstrated the near homo-polarity of the P–I bond, and energy decomposition analysis calculations demonstrated the ability to tune the polarization of the bond with only mild changes in secondary structural features. Finally, the ambi-valent nature of the P–I bond was demonstrated to follow hard–soft considerations in reactions with nucleophiles, with harder nucleophiles preferentially forming products of addition to P and softer nucleophiles to I.

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Enabling Reductive C–N Cross-Coupling of Nitroalkanes and Boronic Acids by Steric Design of P(III)/P(V)═O Catalysts

Cited by 26 publications

References 40 publications

N–N Bond Formation by a Small-Ring Phosphine Catalyst via the P^III/P^V Cycle: Mechanistic Study and Guidelines to Obtain a Good Catalyst

N–N Bond Formation by a Small-Ring Phosphine Catalyst via the P^III/P^V Cycle: Mechanistic Study and Guidelines to Obtain a Good Catalyst

Direct Synthesis of Unprotected Indolines Through Intramolecular sp³ C−H Amination Using Nitroarenes as Aryl Nitrene Precursors

Iodenium or Phosphonium: The Ambi-Valent Character of Iodophosphonium Complexes

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Enabling Reductive C–N Cross-Coupling of Nitroalkanes and Boronic Acids by Steric Design of P(III)/P(V)═O Catalysts

Cited by 26 publications

References 40 publications

N–N Bond Formation by a Small-Ring Phosphine Catalyst via the PIII/PV Cycle: Mechanistic Study and Guidelines to Obtain a Good Catalyst

N–N Bond Formation by a Small-Ring Phosphine Catalyst via the PIII/PV Cycle: Mechanistic Study and Guidelines to Obtain a Good Catalyst

Direct Synthesis of Unprotected Indolines Through Intramolecular sp3 C−H Amination Using Nitroarenes as Aryl Nitrene Precursors

Iodenium or Phosphonium: The Ambi-Valent Character of Iodophosphonium Complexes

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N–N Bond Formation by a Small-Ring Phosphine Catalyst via the P^III/P^V Cycle: Mechanistic Study and Guidelines to Obtain a Good Catalyst

N–N Bond Formation by a Small-Ring Phosphine Catalyst via the P^III/P^V Cycle: Mechanistic Study and Guidelines to Obtain a Good Catalyst

Direct Synthesis of Unprotected Indolines Through Intramolecular sp³ C−H Amination Using Nitroarenes as Aryl Nitrene Precursors