Silver‐Catalyzed Isocyanide‐Alkyne Cycloaddition: A General and Practical Method to Oligosubstituted Pyrroles

Liu, Jianquan; Fang, Zhongxue; Zhang, Qian; Li, Qun; Bi, Xihe

doi:10.1002/ange.201302024

Cited by 77 publications

(8 citation statements)

References 55 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The pioneering works of Yamamoto and de Meijere in 2005 opened up the copper‐catalyzed alkyne‐isocyanide [3+2] cycloaddition reactions, where the phosphine‐catalyzed reaction provided the regiodivergent synthesis of highly substituted pyrroles (Scheme a). In 2013, the groups of Bi and Lei independently reported the silver‐catalyzed alkyne‐isocyanide [3+2] cycloaddition reactions, expanding the alkyne substrate scope to terminal alkynes . Mechanistically, whereas the cationic phosphonium and the anionic carbanion intermediate species were postulated for the Lewis basic phosphine catalysts, the formation of C‐metallated isocyanides has been proposed by a recent experimental and theoretical study .…”

Section: Methodsmentioning

confidence: 99%

“…Based on our experimental observations on the 1,2‐migration of electron‐withdrawing groups, it is reasonable to assume two different mechanistic pathways of 2 H ‐pyrroles (Figure ). When the sp 3 ‐carbon of 2 H ‐pyrrole is substituted with an electron‐withdrawing group and a hydrogen, the preferential reaction pathway involves 1,5‐hydrogen shift to provide pyrroles with two EWGs at the 2‐ and 4‐carbon atoms (Figure a) . The replacement of hydrogen at the sp 3 ‐carbon of 2 H ‐pyrrole with smaller substituents such as a methyl group provides the inert structure of 2 H ‐pyrrole with a smaller bond angle for MeO 2 C–C–CH 3 that is free from the bond migration.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Regioselective Synthesis of Pyrroles from Alkyne‐Isocyanide Click Reactions: An Angle Strain‐Induced Bond Migration Approach

George

Kim

2016

Adv Synth Catal

View full text Add to dashboard Cite

Thed irect regioselective synthesis of highly functionalized pyrrolesw ith twod ifferent electron-withdrawing groups has been developed using an angle strain-induced 1,2-shift of an electron-withdrawing group in 2H-pyrroles.T he preferential migration aptitude of an electron-withdrawing group over alkyla nd aryl groups is believed to be the result of the orbital overlap between the internal alkene and the electron-withdrawing group. Then ewly developed regioselective synthesis of pyrroles featuresawide substrate scope,s imple reaction set-up, andh igh yields( 60-82%), capturing the essence of alkyne-isocyanide "click" reactions.Scheme1.Alkyne-isocyanide "click" reactions and angle strain-induced bond migration to substituted pyrroles.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Regioselective Synthesis of Pyrroles from Alkyne‐Isocyanide Click Reactions: An Angle Strain‐Induced Bond Migration Approach

George

Kim

2016

Adv Synth Catal

View full text Add to dashboard Cite

show abstract

“…72 In 2013, our group overcame this difficulty using silver catalysis, thereby establishing a practical approach for accessing pyrroles 19 (Scheme 17b). 73 After extensively screening the reaction conditions, we found that Ag 2 CO 3 in hot 1,4-dioxane was a suitable system for the synthesis of pyrroles. A variety of terminal alkynes, including aryl, heteroaryl, alkyl, cyclopropyl, alkynyl, hydroxyalkyl, alkenyl, alkoxy, and acetyl acetylenes, smoothly underwent cycloaddition with ethyl isocyanoacetate to afford the desired pyrroles 19 in excellent yields (Scheme 18).…”

Section: Coupling Of Terminal Alkynes With Isocyanidesmentioning

confidence: 99%

Silver-Catalyzed Activation of Terminal Alkynes for Synthesizing Nitrogen-Containing Molecules

et al. 2020

Self Cite

View full text Add to dashboard Cite

Conspectus Alkynes are one of the most abundant chemicals in organic chemistry, and therefore the development of catalytic reactions to transform alkynes into other useful functionalities is of great value. In recent decades, extraordinary advances have been made in this area with transition-metal catalysis, and silver-based reagents are ideal for the activation of alkynes. This high reactivity is probably due to the superior π-Lewis acidic, carbophilic behavior of silver(I), allowing it to selectively activate carbon–carbon triple bonds (CC) through the formation of a silver−π complex. Within this field, we have been interested in the activation and subsequent reactions of readily accessible terminal alkynes for the synthesis of nitrogen-containing compounds, which has generally received less attention than methods involving internal alkynes. This is possibly due to the lack of suitable reactive reaction partners that are compatible under transition metals. Therefore, a thorough understanding of the factors that influence homogeneous silver catalysis and the identification of the appropriate reaction partners can provide a powerful platform for designing more efficient silver-catalyzed reactions of terminal alkynes. In this context, we envisioned that using readily available, environmentally benign, and inexpensive trimethylsilyl azide (TMSN3) or an isocyanide as the nitrogen-donor would be the key to develop novel reactions of terminal alkynes. This Account describes our efforts since 2013 toward the development of novel silver-catalyzed tandem reactions of terminal alkynes with either TMSN3 or isocyanides for the assembly of various nitrogen-containing compounds. The first section of this Account discusses the initial developments in the silver-catalyzed hydroazidation of terminal alkynes with TMSN3 and the subsequent advances made in our laboratory. We first describe the discovery and experimental and computational mechanistic investigations of silver-catalyzed hydroazidation reactions, which is the most efficient strategy reported to date for accessing vinyl azides. Mechanistic study of this hydroazidation reaction provides an alternative activation mode for terminal alkyne conversion in transition metal catalysis. We then present the chemistry of in situ generated vinyl azides, including one-pot tandem radical addition/cyclization or migration reactions of terminal alkynes to access a variety of nitrogen-containing molecules. Finally, we discuss the one-pot, multistep tandem hydroazidation and 1,2-azide migratory gem-difluorination of terminal alkynes for the synthesis of β-difluorinated alkyl azides. The second section describes the silver-catalyzed coupling reactions between terminal alkynes and isocyanides, which offer a straightforward method for accessing synthetically useful building blocks, such as pyrroles, allenamides, benzofuran, vinyl sulfones, indazolines, propiolonitriles, and pyrazoles. The high efficiency, mild conditions, low cost, broad substrate scope, high chemo- and regioselectivity, s...

show abstract

“…During our preparation of this manuscript, Echavarren and Gaydou reported another chemoselective reaction of terminal alkynes with trimethylsilyl azide (TMSÀN 3 ) using gold catalysis, affording tetrazoles (Figure 1 b). [6] Inspired by Jiaos pioneering work and by our long-standing interest in developing transition-metal-catalyzed organic reactions, [7] we herein wish to report an unprecedented chemo-and regioselective hydroazidation of ethynyl carbinols. A general and efficient method to access 2-azidoallyl alcohols has thus been developed (Figure 1 c).…”

mentioning

confidence: 99%

Silver(I)‐Catalyzed Hydroazidation of Ethynyl Carbinols: Synthesis of 2‐Azidoallyl Alcohols

Liu

Zhang

et al. 2014

Angewandte Chemie

Self Cite

View full text Add to dashboard Cite

The hydroazidation of alkynes is the most straightforward pathway to synthetically useful vinyl azides. However, a general hydroazidation of alkynes remains elusive. Herein, a chemo-and regioselective transformation of ethynyl carbinols into vinyl azides is described. This reaction produces a wide variety of 2-azidoallyl alcohols with high efficiency and in good to excellent yields. These compounds constitute a new class of densely functionalized synthetic intermediates. Their synthetic potential has been demonstrated by further transformations into NH aziridines. The mechanistic aspects of the reaction will attract the attention of chemists working on alkyne chemistry and silver catalysis. The findings that are described in this paper represent significant advances in the regioselective hydroelementation of alkynes and open a new reaction manifold for exploitation.

show abstract

Silver‐Catalyzed Isocyanide‐Alkyne Cycloaddition: A General and Practical Method to Oligosubstituted Pyrroles

Cited by 77 publications

References 55 publications

Regioselective Synthesis of Pyrroles from Alkyne‐Isocyanide Click Reactions: An Angle Strain‐Induced Bond Migration Approach

Regioselective Synthesis of Pyrroles from Alkyne‐Isocyanide Click Reactions: An Angle Strain‐Induced Bond Migration Approach

Silver-Catalyzed Activation of Terminal Alkynes for Synthesizing Nitrogen-Containing Molecules

Silver(I)‐Catalyzed Hydroazidation of Ethynyl Carbinols: Synthesis of 2‐Azidoallyl Alcohols

Contact Info

Product

Resources

About