The α-alkylation of ketones with alcohols in pure water catalyzed by a water-soluble Cp*Ir complex bearing a functional ligand

Meng, Chong; Xu, Jing; Tang, Yawen; Ai, Yao; Li, Feng

doi:10.1039/c9nj03345a

Cited by 17 publications

(8 citation statements)

References 96 publications

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“…In 2019, a water‐soluble dinuclear Cp*Ir complex bearing 4, 40, 6, 60‐tetrahydroxy‐2,20‐bipyrimidine as a bridging ligand was developed for the α‐alkylation of ketones with alcohols in pure water (Scheme 11). [18] The importance of the hydroxy group in the ligand for catalytic hydrogen transfer was confirmed by mechanism experiments. Reaction of acetophenone with benzylic alcohols bearing electron‐donating and electron‐withdrawing substituents generated the desired products in 79–84% yields.…”

Section: The α‐Alkylation Of Ketonesmentioning

confidence: 89%

Recent Advances for Alkylation of Ketones and Secondary Alcohols Using Alcohols in Homogeneous Catalysis

2022

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The alkylation of ketones or secondary alcohols using alcohols as alkylating agents via hydrogen borrowing strategy presents a powerful method for the synthesis of �-alkylated ketones. In this review, we summarize the progress catalyzed by Ir, Pd, Rh, Ru, Mn, Fe, Co, Ni, and Cu catalysts for the α-alkylation of ketones with alcohols and crosscoupling of secondary alcohols with alcohols from 2017 to 2021. A wide range of ketones (aromatic and aliphatic ketones) and alcohols (benzylic and aliphatic primary alcohols, aromatic and aliphatic secondary alcohols, alkenyl alcohols, and diols) are well tolerated. Furthermore, we also discuss current challenges and propose perspectives on the coming development in this filed. The objective of the present review is to give an overview on recent advances for α-alkylation of ketones with alcohols and β-alkylation of secondary alcohols with alcohols. Finally, we hope that this review will give inspirations on alkylation of ketones or secondary alcohols with alcohols.

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Section: The α‐Alkylation Of Ketonesmentioning

confidence: 89%

Recent Advances for Alkylation of Ketones and Secondary Alcohols Using Alcohols in Homogeneous Catalysis

2022

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“…A comparison of the performances of reported protonresponsive catalysts was made (see, Scheme S2). It is apparent that 1 exhibits better catalytic efficacy in terms of lower base loading and higher TON and TOF values for both α-alkylation of ketones [38,110,121,[135][136][137][138] and β-alkylation of secondary alcohols. [87,94,104,106,139]…”

Section: β-Alkylation Of Secondary Alcohols Using Primary Alcoholsmentioning

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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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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“…Then addition of C=C bond of unsaturated ketones to obtain carbanion‐iridium species Int‐V . Finally, the target products are obtained and alkoxy iridium species Int‐I and Int‐I ’ recycle under the action of alcohols [25d,e] . Simultaneously, the iridium hydride Int‐III decomposes into alkoxy iridium species Int‐I and Int‐I ’ under the action of alcohol 1 a and 2 a , which releases one molecule of hydrogen respectively.…”

Section: Resultsmentioning

confidence: 99%

Iridium Complexes as Efficient Catalysts for Construction of α‐Substituted Ketones via Hydrogen Borrowing of Alcohols in Water

et al. 2021

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Ketones are of great importance in synthesis, biology, and pharmaceuticals. This paper reports an iridium complexes‐catalyzed cross‐coupling of alcohols via hydrogen borrowing, affording a series of α‐alkylated ketones in high yield (86 %–95 %) and chemoselectivities (>99 : 1). This methodology has the advantages of low catalyst loading (0.1 mol%) and environmentally benign water as the solvent. Studies have shown the amount of base has a great impact on chemoselectivities. Meanwhile, deuteration experiments show water plays an important role in accelerating the reduction of the unsaturated ketones intermediates. Remarkably, a gram‐scale experiment demonstrates this methodology of iridium‐catalyzed cross‐coupling of alcohols has potential application in the practical synthesis of α‐alkylated ketones.

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The α-alkylation of ketones with alcohols in pure water catalyzed by a water-soluble Cp*Ir complex bearing a functional ligand

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 α-alkylation of ketones with alcohols in water.

Cited by 17 publications

References 96 publications

Recent Advances for Alkylation of Ketones and Secondary Alcohols Using Alcohols in Homogeneous Catalysis

Recent Advances for Alkylation of Ketones and Secondary Alcohols Using Alcohols in Homogeneous Catalysis

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

Iridium Complexes as Efficient Catalysts for Construction of α‐Substituted Ketones via Hydrogen Borrowing of Alcohols in Water

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