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Journal ArticleDOI

TfOH-Catalyzed N-H Insertion of α-Substituted-α-Diazoesters with Anilines Provides Access to Unnatural α-Amino Esters.

19 Feb 2021-Journal of Organic Chemistry (American Chemical Society (ACS))-Vol. 86, Iss: 4, pp 3223-3231
TL;DR: A time-economical TfOH-catalyzed N-H insertion between anilines and α-alkyl and αaryl-α-diazoacetates was proposed in this article.
Abstract: A time-economical TfOH-catalyzed N-H insertion between anilines and α-alkyl and α-aryl-α-diazoacetates provides a straightforward approach to access unnatural α-amino esters, which readily undergo various transformations and can thus be used for the synthesis of pharmaceutically relevant molecules. The α-amino esters were obtained in moderate to excellent yields.
Citations
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Journal ArticleDOI
TL;DR: In this paper, the authors developed a methodology for the construction of significant 2,3-dihydrobenzofuran scaffolds bearing a quaternary carbon center at the C2 position by means of [4 + 1] annulation reactions between p-quinone methides and α-aryl diazoacetates as C1 synthons through organocatalysis by readily accessible TfOH catalyst under mild and transition metal-free conditions.
Abstract: We have developed a methodology for the greatly efficient construction of significant 2,3-dihydrobenzofuran scaffolds bearing a quaternary carbon center at the C2 position by means of [4 + 1] annulation reactions between p-quinone methides and α-aryl diazoacetates as C1 synthons through organocatalysis by readily accessible TfOH catalyst under mild and transition metal-free conditions. This metal-free protocol furnishes an operationally simple and swift process for the free assembly of diverse highly functionalized 2,3-dihydrobenzofurans and also features broad substrate scope, excellent functional group compatibility, and environmental friendliness. Mechanistic investigation suggested that the reaction undergoes a rapid cascade protonation/intermolecular Michael addition/intramolecular substitution process.

14 citations

Journal ArticleDOI
TL;DR: In this article , a triflic acid promoted multi-component synthesis of functionalized S-benzyl dithiocarbamates from diazo compounds, carbon disulfide and secondary amines is reported.
Abstract: Triflic acid promoted multi-component synthesis of functionalized S-benzyl dithiocarbamates from diazo compounds, carbon disulfide and secondary amines is reported. The reactions proceeded at room temperature and gave the desired dithiocarbamates in good yields. Wide-substrate scope and easy operation are the important features of this methodology.

5 citations

Journal ArticleDOI
TL;DR: In this article, a newly developed, facile and sustainable strategy, in which zinc salt, melamine and ethyl cellulose are applied as pore-forming agent, nitrogen and carbon source respectively, has been disclosed for the synthesis of Fe/N-codoped carbon materials.

5 citations

Journal ArticleDOI
TL;DR: This protocol highlights the regioselectivity of alkylation of indazoles and a metal-free catalysis system, affording N2-alkylated products in good to excellent yields with high regiOSElectivity (N2/N1 up to 100/0) and excellent functional group tolerance.

5 citations

Journal ArticleDOI
TL;DR: In this article , a TBAI-catalyzed S-H and N-H insertion reaction of α-diazoesters with thiophenols and aromatic amines under metal-free conditions has been described, furnishing a straightforward and general platform for the synthesis of various thioethers and 2-amino-2-oxoacetates.
Abstract: Mild, convenient, and effective TBAI-catalyzed S-H and N-H insertion reactions of α-diazoesters with thiophenols and aromatic amines under metal-free conditions have been described, furnishing a straightforward and general platform for the synthesis of various thioethers and 2-amino-2-oxoacetates in moderate to excellent yields. Moreover, this strategy features simple operation, mild conditions, broad substrate scope, and easy scale-up.

5 citations

References
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Journal ArticleDOI
TL;DR: The following review will explore the historical development of X-H insertion and give an up-to-date account of the metal catalysts most often employed, including an assessment of their strengths and weaknesses.
Abstract: Catalysed X–H insertion reactions into diazo compounds (where X is any heteroatom) are a powerful yet underutilized class of transformations. The following review will explore the historical development of X–H insertion and give an up-to-date account of the metal catalysts most often employed, including an assessment of their strengths and weaknesses. Despite decades of development, recent work on enantioselective variants, as well as applying catalytic X–H insertion towards problems in chemical biology indicate that this field has ample room for innovation.

394 citations

Journal ArticleDOI
Bin Liu1, Shou-Fei Zhu1, Wei Zhang1, Chao Chen1, Qi-Lin Zhou1 
TL;DR: A highly efficient copper-catalyzed asymmetric insertion of α-diazoesters into N−H bonds has been realized by using chiral spiro bisoxazoline ligands, affording α-amino acid derivatives in high yields with excellent enantioselectivities.
Abstract: A highly efficient copper-catalyzed asymmetric insertion of α-diazoesters into N−H bonds has been realized by using chiral spiro bisoxazoline ligands, affording α-amino acid derivatives in high yields with excellent enantioselectivities.

201 citations

Journal ArticleDOI
27 Jul 2020
TL;DR: In this article, the authors illustrate three distinct green approaches, studying the novel reactivities with environmentally innocuous reagents to improve the synthetic efficiency, utilization of natural feedstocks, and employment of green energy to facilitate various important chemical transformations.
Abstract: Despite their impressive capacity to access diverse functional groups and to synthesize structurally complex molecules, the majority of the organic reactions suffers from harsh conditions, low atom economy, and hazardous waste production. The goal of our research is geared towards developing efficient methods to minimize the adverse environmental impact and contributing to chemical sustainability. Herein, we illustrate three distinct green approaches, studying the novel reactivities with environmentally innocuous reagents to improve the synthetic efficiency, utilization of natural feedstocks, and employment of green energy to facilitate various important chemical transformations. From this perspective article, we hope to provide an overview of green synthetic chemistry and inspire the expansion of the field in the future.

141 citations

Journal ArticleDOI
Mao-Lin Li1, Jin-Han Yu1, Yi-Hao Li1, Shou-Fei Zhu1, Qi-Lin Zhou1 
22 Nov 2019-Science
TL;DR: High enantioselective carbene insertion into N–H bonds of aliphatic amines using two catalysts in tandem: an achiral copper complex and chiral amino-thiourea, compatible with a broad range of diazo ester and amine coupling partners.
Abstract: Aliphatic amines strongly coordinate, and therefore easily inhibit, the activity of transition-metal catalysts, posing a marked challenge to nitrogen-hydrogen (N-H) insertion reactions. Here, we report highly enantioselective carbene insertion into N-H bonds of aliphatic amines using two catalysts in tandem: an achiral copper complex and chiral amino-thiourea. Coordination by a homoscorpionate ligand protects the copper center that activates the carbene precursor. The chiral amino-thiourea catalyst then promotes enantioselective proton transfer to generate the stereocenter of the insertion product. This reaction couples a wide variety of diazo esters and amines to produce chiral α-alkyl α-amino acid derivatives.

134 citations

Journal ArticleDOI
TL;DR: Chiral spiro phosphoric acids as chiral proton-transfer shuttle (CPTS) catalysts are proven to be efficient catalysts for the proton transfer of active intermediates in carbene insertion reactions, and upon combining with achiral dirhodium catalysts, the CPTS catalysts accomplish highly enantioselective insertions of N-h, S-H, and C-H bonds.
Abstract: Transition metal-catalyzed carbene insertion into X-H bonds (X = N, O, S, and C) represents a typical carbene transfer reaction and has been widely used in organic synthesis. The enantioselectivity-determining step in some of these insertion reactions is the proton transfer of active intermediates such as ylides, metal enolates, or free enols. Since most of the traditional chiral transition metal catalysts tend to dissociate from these active intermediates and cannot be involved in the proton-transfer step, enantiocontrol of these insertion reactions has long been a challenging task. Since 2011, we have developed chiral spiro phosphoric acids as chiral proton-transfer shuttle (CPTS) catalysts, which have been proven to be efficient catalysts for the proton transfer of active intermediates in carbene insertion reactions. Upon combining with achiral dirhodium catalysts, the CPTS catalysts accomplish highly enantioselective insertions of N-H, S-H, and C-H bonds. Herein, a number of important chiral building blocks, including α-amino acid derivatives, α-amino ketones, α-thioesters, and α,α-diaryl acetates, were prepared with high yields and high enantioselectivities through these insertion reactions.

130 citations