Copper-catalyzed direct oxidative annulation of N-iminopyridinium ylides with terminal alkynes using O<sub>2</sub>as oxidant

Ding, Shengtao; Yan, Yuepeng; Jiao, Ning

doi:10.1039/c2cc33706a

Cited by 90 publications

(29 citation statements)

References 72 publications

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“…The mechanistic studies suggested that a Cu(I)/Cu(III) catalytic cycle was involved, where Cu(I) was oxidized by O 2 to form the Cu(III) exocyclic species 32 . During the process, silver carbonate would serve as a cocatalyst to promote the formation of intermediate alkynyl copper(I) species 35 (Scheme ) 19…”

Section: Ch Functionalization Of N‐imide Ylidesmentioning

confidence: 99%

Graphene Nanoplatelets: Electrochemical Properties and Applications for Oxidation of Endocrine‐Disrupting Chemicals

Wan

Cai

Liu

et al. 2013

Chemistry A European J

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In most graphene-based electrochemical applications, graphene nanoplatelets (GNPs) have been applied. Now, for the first time, electrochemical properties of GNPs, namely, its electrochemical activity, potential window, and double-layer capacitance, have been investigated. These properties are compared with those of carbon nanotubes (CNTs). GNP- and CNT-coated electrodes were then applied for electrochemical oxidation of endocrine-disrupting chemicals. The GNP-coated electrode was characterized by atomic force microscopy and electrochemical techniques. Compared with the CNT-coated electrode, higher peak current for the oxidation of 4-nonylphenol is achieved on the GNP-coated electrode, together with lower capacitive current. Electrochemical oxidation of 2,4-dichlorophenol, bisphenol A, and octylphenol in the absence or presence of 4-nonylphenol was studied on the GNP-coated electrode. The results suggest that GNPs have better electrochemical performance than CNTs and are thus more promising for electrochemical applications, for example, electrochemical detection and removal of endocrine-disrupting chemicals.

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Section: Ch Functionalization Of N‐imide Ylidesmentioning

confidence: 99%

Graphene Nanoplatelets: Electrochemical Properties and Applications for Oxidation of Endocrine‐Disrupting Chemicals

Wan

Cai

Liu

et al. 2013

Chemistry A European J

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“…Of particular relevance is the propensity of these aminides to undergo intermolecular [3+ +2] dipolarc ycloadditions with electron-deficient alkynes [28] or terminal alkynes in the presence of silver salts andp alladium [29] or copper [30] catalysts to yield pyrazolo[1,5-a]pyridines,o rp yrido[1,2-a]indazolesf rom benzyne precursors. [31] Stereoselective [3+ +3]-couplings with vinylogous rhodium carbenes, [32] or between cyclopropanesa nd (iso)quinolinium-N-aminides [33] are also known.O ther transformationsi nclude stereoselective reductions, [34] directed C À Hf unctionalisations, [35] intramolecular cyclisations with tethered enolates or thiocyanates, [36] as well as photochemicale limination of pyridine to form electrophilic acyl nitrenes, or ringexpansion to diazepines.…”

mentioning

confidence: 99%

Efficient and Flexible Synthesis of Highly Functionalised 4‐Aminooxazoles by a Gold‐Catalysed Intermolecular Formal [3+2] Dipolar Cycloaddition

2016

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Oxazolesa re important motifs within bioactive and functional materials.C omplex, fully substituteda nd functionalised 4-aminooxazoles are accessed by an efficienti ntermolecular reactionb etween an ynamide and an N-acylpyridinium N-aminide in the presence of ag old catalyst. Thef ormal [3+ +2] dipolar cycloaddition employs an ucleophilic nitrenoid approach to access the 1,3-N,O-dipole character in ac ontrollable fashion.T he selectivity for ac ycloaddition pathwayp rovides as tark contrast against the indiscriminate reactivity of electrophilic acyl nitrenes.P rotocolsf or the formation of acylfunctionalised aminides are reported from accessible precursors including carboxylic estersa nd acids.T he function of these aminides in the oxazole-forming reaction has been exploreda nd it is shown that substantial elaboration is accommodated despite proximity to the reactivec entre.A saresult functional oxazole-based motifs,s uch as chiral oxazoles with biologically pertinent substitution patterns,a re readily accessible.T he use of ynamide types that are unexplored or little used in gold catalysis has been evaluated. Unusual all-heteroatom substitution patterns around the oxazole are shown to be accessible using thio-ynamides.T he studys hows that ac lose stoichiometry of reactantsi ss uitable alongsider elatively low loadings of the bench-stable precatalysts in practicallys traightforward multi-mmol scale reactions.T he efficiency and flexibility of this regioselective intermolecular preparation is demonstrated in the ready synthesis of oxazoles with substantial structural and functional group variation.

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“…Through oxidative Cu-catalysis, we developed an aerobic oxidative dehydrogenative annulation of N-iminopyridinium ylides with terminal alkynes via C-H bond direct alkynylation leading to pyrazolo[1,5-a]pyridine derivatives (Scheme 1a). [6] zation. Intermediate B undergoes reductive elimination to afford the direct alkynylation intermediate C, in which the alkyne can be activated by copper catalyst.…”

Section: Methodologies Through C-h Bond Cleavagementioning

confidence: 99%

Reoxidation of Transition‐metal Catalysts with O₂

Jiao

2017

Chin. J. Chem.

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Transition‐metal catalyzed oxidation reactions are central components of organic chemistry. On behalf of green and sustainable chemistry, molecular oxygen (O2) has been considered as an ideal oxidant due to its natural, inexpensive, and environmentally friendly characters, and therefore offers attractive academic and industrial prospects. In recent years, some powerful organic oxidation methods have been continuously developed. Among them, the use of molecular oxygen (O2) as a green and sustainable oxidant has attracted considerable attentions. However, the development of new transition metal‐catalyzed protocols using O2 as an ideal oxidant is highly desirable but very challenging because of the low standard electrode potential of O2 to reoxidize the transition‐metal catalysts. In this Account, we highlight some of our progress toward the use of transition‐metal catalyzed aerobic oxidation reactions. Through the careful selection of ligand and the acidic additives, we have successfully realized the reoxidation of Cu, Pd, Mn, Fe, Ru, Rh, and bimetallic catalysts under O2 or air atmosphere (1 atm) for the oxidative coupling, oxygenation reactions, oxidative C‐H/C‐C bond cleavage, oxidative annulation, and olefins difunctionalization reactions. Most of the reactions can tolerate a range of functional groups. These methods provide new strategies for the green synthesis of alkynes, (α‐keto)amides/esters, ketones/diones, O/N‐heterocycles, β‐azido alcohols, and nitriles. The high efficiency, low cost, and simple operation under air make these methodologies very attractive and practical. We will also discuss the mechanisms of these reactions which might be useful to promote the new type of aerobic oxidative reaction design.

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Copper-catalyzed direct oxidative annulation of N-iminopyridinium ylides with terminal alkynes using O₂as oxidant

Abstract: The aerobic direct dehydrogenative annulation of N-iminopyridinium ylides with terminal alkynes leading to pyrazolo[1,5-a]pyridine derivatives has been developed.

Cited by 90 publications

References 72 publications

Graphene Nanoplatelets: Electrochemical Properties and Applications for Oxidation of Endocrine‐Disrupting Chemicals

Graphene Nanoplatelets: Electrochemical Properties and Applications for Oxidation of Endocrine‐Disrupting Chemicals

Efficient and Flexible Synthesis of Highly Functionalised 4‐Aminooxazoles by a Gold‐Catalysed Intermolecular Formal [3+2] Dipolar Cycloaddition

Reoxidation of Transition‐metal Catalysts with O₂

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Copper-catalyzed direct oxidative annulation of N-iminopyridinium ylides with terminal alkynes using O2as oxidant

Abstract: The aerobic direct dehydrogenative annulation of N-iminopyridinium ylides with terminal alkynes leading to pyrazolo[1,5-a]pyridine derivatives has been developed.

Cited by 90 publications

References 72 publications

Graphene Nanoplatelets: Electrochemical Properties and Applications for Oxidation of Endocrine‐Disrupting Chemicals

Graphene Nanoplatelets: Electrochemical Properties and Applications for Oxidation of Endocrine‐Disrupting Chemicals

Efficient and Flexible Synthesis of Highly Functionalised 4‐Aminooxazoles by a Gold‐Catalysed Intermolecular Formal [3+2] Dipolar Cycloaddition

Reoxidation of Transition‐metal Catalysts with O2

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Copper-catalyzed direct oxidative annulation of N-iminopyridinium ylides with terminal alkynes using O₂as oxidant

Reoxidation of Transition‐metal Catalysts with O₂