A General and Mild Catalytic α‐Alkylation of Unactivated Esters Using Alcohols

Guo, Lingling; Ma, Xiaochen; Fang, Huaquan; Jia, Xiangqing; Huang, Zheng

doi:10.1002/anie.201410293

Cited by 64 publications

(36 citation statements)

References 49 publications

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“…[6,7] Thus, the results in this manuscript provide an effective and green method for α-alkylation of unactivated amides and esters, using a new type of Ru catalysts. [6,7] Thus, the results in this manuscript provide an effective and green method for α-alkylation of unactivated amides and esters, using a new type of Ru catalysts.…”

Section: Discussionmentioning

confidence: 87%

“…[16c-d] As an extension, herein we present a bidentate Ru(II)-NC complex {(C 5 H 4 N)-(C 6 H 4 )}RuCl(CO)(PPh 3 ) 2 (1), which is active for the dehydrogenative reaction from primary alcohols to carboxylic acids, [17] for α-alkylation of unactivated amides and esters with alcohols (Scheme 1). [6,7] It is worth noting that complex 1 is easily synthesized from a commercially cheap ligand in high yield, and its efficiency is comparable to the best Ir catalyst reported up to date.…”

Section: Introductionmentioning

confidence: 82%

“…In 2010, Ishii's group reported the first catalytic α-alkylation of unactivated esters catalyzed by [IrCl(cod)] 2 /PPh 3 (Scheme 1). [6,7] For amide alkylation, the reactions proceeded well at 80°C with 0.5 mol% catalyst, [7] and when the substrates were esters, 60°C was even enough. [5] Since then, several other transition-metal catalysts, including Ir, [6,7] Ru, [8][9][10] Co, [11] Ni [12] and Mn [13][14][15] complexes, have been developed, most of which are based on pincer-type ligands.…”

Section: Introductionmentioning

confidence: 99%

“…[4] Later in 2013, Huang et al developed the α-alkylation of unactivated amides using an Ir-pincer complex (Scheme 1). [6] Some other noble metal catalysts, such as the NNNÀ Ru complex developed by Ryu's group, [8] and the PNP-Ru [9] and NHCÀ Ru(p-cym) [10] complexes developed by Gnanaprakasam et al, were not as effective as Huang's catalyst, and 140°C were needed for amide alkylation (Scheme 1). For earth-abundant base metal catalysts, harsh reaction conditions and high catalyst loadings were needed for good conversion in most of the cases, and sometimes the substrates were limited.…”

Section: Introductionmentioning

confidence: 99%

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Bidentate Ru(II)‐NC Complexes as Catalysts for α‐Alkylation of Unactivated Amides and Esters

Gong

Yang

et al. 2019

ChemCatChem

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Five Ru(II)-NC complexes were tested as catalysts for αalkylation of unactivated amides using alcohols as alkylating agents, and complex {(C 5 H 4 N)-(C 6 H 4 )}RuCl(CO)(PPh 3 ) 2 (1) showed the highest activity. With 0.5 mol% catalyst loading, a series of α-alkylated amides were isolated at 80°C within 6 hours.Furthermore, under similar conditions, complex 1 was also active for α-alkylation of unactivated esters with alcohols, and the reaction time was shortened to 1.5 hours. The catalytic performance of 1 is comparable to the best reported catalyst. Reaction of N,N-dimethylcinnamamide with benzyl alcohol:Ruthenium catalyst (0.005 mmol), t-BuOK (1.5 mmol), internal standard (dodecane, 0.5 mmol), benzyl alcohol (1 mmol) and N,Ndimethylcinnamamide (1 mmol) were dissolved in toluene (3 mL) and the solution was heated to 80°C for 6 h under an Ar atmosphere. The yield was calculated by GC using dodecane as the internal standard.

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Section: Discussionmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 82%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Bidentate Ru(II)‐NC Complexes as Catalysts for α‐Alkylation of Unactivated Amides and Esters

Gong

Yang

et al. 2019

ChemCatChem

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“…46 This novel method could be applied to the synthesis of carboxylic acid derivatives with diverse structures and functional groups, some of which would be impossible to access using conventional enolate alkylations with alkyl halides. 46…”

Section: Scheme 40 Palladium-catalyzed Arylation Of Sp 3 -Carbon-hydrmentioning

confidence: 99%

Advances in Transition-Metal-Catalyzed Direct sp3-Carbon–Hydrogen Bond Functionalization

Zhang

Wang

Xing

2015

Synlett

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Transition-metal-catalyzed direct carbon-hydrogen bond functionalization has made significant advances in the field of carbonhydrogen bond activation over the past decades. This methodology has the potential to be used in many different areas of chemistry; for example, it can provide an opportunity for the synthesis of various kinds of complex compounds. This account mainly focuses on recent advances in transition-metal-catalyzed direct sp 3 -carbon-hydrogen bond functionalization to form carbon-carbon bonds. 1 Introduction 2 Carbon-Carbon Bond Formation via Direct sp 3 -Carbon-Hydrogen Bond Functionalization 2.1 Coupling of sp 3 -Carbon-Hydrogen and sp-Carbon-Hydrogen Bonds 2.2 Coupling of sp 3 -Carbon-Hydrogen and sp 2 -Carbon-Hydrogen Bonds 2.3 Coupling of sp 3 -Carbon-Hydrogen and sp 3 -Carbon-Hydrogen Bonds 2.4 Coupling of sp 3 -Carbon-Hydrogen and C-X Bonds 3 Conclusion Key words transition metals, catalysis, carbon-carbon bond formations, cross-dehydrogenative coupling, direct bond functionalizations Carbon-Carbon Bond Formation via Direct sp 3 -Carbon-Hydrogen Bond FunctionalizationThe oxidative coupling of two different carbon-hydrogen bonds was termed cross-dehydrogenative coupling (CDC) by Li's group 4 in 2004, and it has become an increasing field of interest. In the past decade, a growing number of efficient procedures and novel methods have been introduced. These methods make the connection of sp 3 -carbonhydrogen with sp-carbon-hydrogen, sp 2 -carbon-hydrogen, sp 3 -carbon-hydrogen, and C-X bonds a reality (Scheme 1). 4,5 However, the development of chemo-, regio-, and stereoselective sp 3 -carbon-carbon bond formation reactions is still one of the most challenging tasks in organic synthesis.

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A Convenient Ruthenium‐Catalysed α‐Methylation of Carbonyl Compounds using Methanol

Dang

Seayad

2016

Adv Synth Catal

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An efficient ruthenium catalyst is reported, for the first time, to catalyse the α‐methylation of ketones and esters using methanol as a green methylating agent. The in situ generated catalyst from the complexes [RuCp*Cl2]2 or [RuCp*Cl2]n with dpePhos provided up to quantitative yields in the presence of only 20 mol% of lithium tert‐butoxide (LiO‐t‐Bu) as a base. Regioselective mono‐ or multi‐methylation could be effectively controlled by temperature. This catalyst system was also effective for the one‐pot sequential α‐alkylation–α‐methylation of methyl ketones and conjugate reduction–α‐methylation of α,β‐unsaturated ketones to synthesise α‐branched ketones. An application of the α‐methylation of esters using the ruthenium catalyst was demonstrated for an alternative catalytic synthesis of Ketoprofen.magnified image

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A General and Mild Catalytic α‐Alkylation of Unactivated Esters Using Alcohols

Cited by 64 publications

References 49 publications

Bidentate Ru(II)‐NC Complexes as Catalysts for α‐Alkylation of Unactivated Amides and Esters

Bidentate Ru(II)‐NC Complexes as Catalysts for α‐Alkylation of Unactivated Amides and Esters

Advances in Transition-Metal-Catalyzed Direct sp3-Carbon–Hydrogen Bond Functionalization

A Convenient Ruthenium‐Catalysed α‐Methylation of Carbonyl Compounds using Methanol

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