The N-alkylation of sulfonamides with alcohols in water catalyzed by a water-soluble metal–ligand bifunctional iridium complex [Cp*Ir(biimH2)(H2O)][OTf]2

Ai, Yao; Liu, Pengcheng; Ran, Liang; Liu, Yan; Li, Feng

doi:10.1039/c9nj02542a

Cited by 20 publications

(16 citation statements)

References 102 publications

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“…The catalysts bearing these ligands effectively promote the reactions that involve hydride and proton management, such as (de)hydrogenation [1][2][3][4][5][6][7][8][9][10][11] and borrowing-hydrogenation. [12][13][14][15][16] The nature (acid-base properties) and the position/orientation of proton-responsive unit, along with the metal-hydricity, [17] are the key considerations to enable metal-ligand cooperation (MLC) [18][19][20] for efficient hydrogen delivery/acceptance. [21][22][23][24] Among the various designs explored, the protic catalysts based on the reversible (de)protonation of bipyridonate ligand (Scheme 1a) for catalyzing dehydrogenative oxidation of alcohols under mild conditions.…”

Section: Introductionmentioning

confidence: 99%

“…The ligand electronics controls proton transfer at proton‐responsive unit and hydride transfer at metal center to/from a suitable acceptor/donor. The catalysts bearing these ligands effectively promote the reactions that involve hydride and proton management, such as (de)hydrogenation [1–11] and borrowing‐hydrogenation [12–16] . The nature (acid‐base properties) and the position/orientation of proton‐responsive unit, along with the metal‐hydricity, [17] are the key considerations to enable metal‐ligand cooperation (MLC) [18–20] for efficient hydrogen delivery/acceptance [21–24] .…”

Section: Introductionmentioning

confidence: 99%

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A Proton‐Responsive Pyridyl(benzamide)‐Functionalized NHC Ligand on Ir Complex for Alkylation of Ketones and Secondary Alcohols

Kaur

Reshi

Patra

et al. 2021

Chemistry A European J

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A Cp*Ir(III) complex (1) of a newly designed ligand L 1 featuring a proton-responsive pyridyl(benzamide) appended on N-heterocyclic carbene (NHC) has been synthesized. The molecular structure of 1 reveals a dearomatized form of the ligand. The protonation of 1 with HBF 4 in tetrahydrofuran gives the corresponding aromatized complex [Cp*Ir(L 1 H)Cl]BF 4 (2). Both compounds are characterized spectroscopically and by X-ray crystallography. The protonation of 1 with acid is examined by 1 H NMR and UV-vis spectra. The proton-responsive character of 1 is exploited for catalyzing α-alkylation of ketones and β-alkylation of secondary alcohols using primary alcohols as alkylating agents through hydrogen-borrowing methodology. Compound 1 is an effec-tive catalyst for these reactions and exhibits a superior activity in comparison to a structurally similar iridium complex [Cp*Ir(L 2 )Cl]PF 6 (3) lacking a proton-responsive pendant amide moiety. The catalytic alkylation is characterized by a wide substrate scope, low catalyst and base loadings, and a short reaction time. The catalytic efficacy of 1 is also demonstrated for the syntheses of quinoline and lactone derivatives via acceptorless dehydrogenation, and selective alkylation of two steroids, pregnenolone and testosterone. Detailed mechanistic investigations and DFT calculations substantiate the role of the proton-responsive ligand in the hydrogen-borrowing process.À OH/=O, À CH 2 /=CH and À NH/ = N motifs on pyridine, [25][26][27] bipyridine, [28][29][30][31][32] bipyrimidine [33] and azole-pyridine/ pyrimidine [34][35][36][37] are particularly effective. Some of the representative examples that have been employed for catalyzing (de) hydrogenation and alkylation reactions are given in Scheme 1. Yamaguchi and co-workers reported a Cp*Ir(III) compound with

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Proton‐Responsive Pyridyl(benzamide)‐Functionalized NHC Ligand on Ir Complex for Alkylation of Ketones and Secondary Alcohols

Kaur

Reshi

Patra

et al. 2021

Chemistry A European J

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“…Subsequent, Yu and Xu studied the use of various metal‐based precursors, among others, IrCl 3 and IrO 2 [9g] . Later, Li and co‐workers developed reaction conditions that allowed to perform the mono‐ N ‐alkylation of sulfonamides in water using water‐soluble iridium complexes [9j,n] …”

Section: Introductionmentioning

confidence: 99%

Mono‐N‐Alkylation of Sulfonamides with Alcohols Catalyzed by Iridium N‐Heterocyclic Carbene‐Phosphine Complexes

Peters

Tan

et al. 2022

Asian J Org Chem

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A N‐heterocyclic carbene‐phosphine iridium complex is presented for the efficient and selective mono‐N‐alkylation of sulfonamides with alcohols based on a borrowing hydrogenation strategy. Herein, water is the only by‐product and this methodology thus offers a more environmentally benign and interesting alternative to the use of traditional alkylating reagents. This facile protocol tolerates a large number of (hetero) aromatic and aliphatic sulfonamides as well as (hetero) aromatic and aliphatic alcohols to obtain the desired product is high isolated yield (up to 98%). The alkylation completely retards after the formation of the secondary sulfonamide and no over‐alkylation was observed in all cases. The option to run the reaction under solvent‐free conditions as well as the scalability of this borrowing hydrogenation are key features of this protocol.

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“…Despite these advances, the N-alkylation of amines with methanol in aqueous solution is regarded to be an extremely challenging subject and remained unexplored till date. As a continuing effort in the development of iridium-catalyzed environmentally friendly reactions, , we herein wish to report the first example of N-methylation of amines with methanol in aqueous solution catalyzed by a water-soluble iridium complex.…”

Section: Introductionmentioning

confidence: 99%

N-Methylation of Amines with Methanol in Aqueous Solution Catalyzed by a Water-Soluble Metal–Ligand Bifunctional Dinuclear Iridium Catalyst

et al. 2020

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The N-methylation of amines with methanol in aqueous solution was proposed and accomplished by using a watersoluble metal−ligand bifunctional dinuclear iridium catalyst. In the presence of [(Cp*IrCl) 2 (thbpym)][Cl] 2 (1 mol %), a range of desirable products were obtained in high yields under environmentally benign conditions. Notably, this research exhibited the potential of transition metal-catalyzed activation of methanol as a C1 source for the construction of the C−N bond in aqueous solution.

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The N-alkylation of sulfonamides with alcohols in water catalyzed by a water-soluble metal–ligand bifunctional iridium complex [Cp*Ir(biimH₂)(H₂O)][OTf]₂

Abstract: A water-soluble dinuclear Cp*Ir complex bearing 4,4′,6,6′-tetrahydroxy-2,2′-bipyrimidine as a bridging ligand was found to be a highly effective catalyst for the N-alkylation of ketones with alcohols in water.

Cited by 20 publications

References 102 publications

A Proton‐Responsive Pyridyl(benzamide)‐Functionalized NHC Ligand on Ir Complex for Alkylation of Ketones and Secondary Alcohols

A Proton‐Responsive Pyridyl(benzamide)‐Functionalized NHC Ligand on Ir Complex for Alkylation of Ketones and Secondary Alcohols

Mono‐N‐Alkylation of Sulfonamides with Alcohols Catalyzed by Iridium N‐Heterocyclic Carbene‐Phosphine Complexes

N-Methylation of Amines with Methanol in Aqueous Solution Catalyzed by a Water-Soluble Metal–Ligand Bifunctional Dinuclear Iridium Catalyst

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