scholarly journals A combined experimental and theoretical study on the reactivity of nitrenes and nitrene radical anions

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Yujing Guo ◽  
Chao Pei ◽  
Rene M. Koenigs
Keyword(s):  
Radical Anion ◽  
Room Temperature ◽  
Theoretical Study ◽  
Transition Metal Catalysts ◽  
Transfer Reactions ◽  
Mechanistic Studies ◽  
Reaction Conditions ◽  
Nitrene Transfer ◽  
Triplet Nitrene ◽  
Nitrogen Bonds

AbstractNitrene transfer reactions represent one of the key reactions to rapidly construct new carbon-nitrogen bonds and typically require transition metal catalysts to control the reactivity of the pivotal nitrene intermediate. Herein, we report on the application of iminoiodinanes in amination reactions under visible light photochemical conditions. While a triplet nitrene can be accessed under catalyst-free conditions, the use of a suitable photosensitizer allows the access of a nitrene radical anion. Computational and mechanistic studies rationalize the access and reactivity of triplet nitrene and nitrene radical anion and allow the direct comparison of both amination reagents. We conclude with applications of both reagents in organic synthesis and showcase their reactivity in the reaction with olefins, which underline their markedly distinct reactivity. Both reagents can be accessed under mild reaction conditions at room temperature without the necessity to exclude moisture or air, which renders these metal-free, photochemical amination reactions highly practical.

scholarly journals Synthesis of Pyrazolo-Fused 4-Azafluorenones in an Ionic Liquid. Mechanistic Insights by Joint Studies Using DFT Analysis and Mass Spectrometry

Catalysts ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 820
Author(s):  
Efraín Polo ◽  
Valentina Arce-Parada ◽  
Xaviera A. López-Cortés ◽  
Jesús Sánchez-Márquez ◽  
Alejandro Morales-Bayuelo ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Density Functional ◽  
Room Temperature ◽  
Theoretical Study ◽  
Environmentally Benign ◽  
Reaction Conditions ◽  
Conceptual Density Functional Theory ◽  
Functional Theory ◽  
Three Component Reaction ◽  
Work Up

A series of pyrazolo-fused 4-azafluorenones (indeno[1,2-b]pyrazolo[4,3-e]pyridines, IPP) were synthesized via the three-component reaction between arylaldehydes, 3-methyl-1H-pyrazol-5-amine and 1,3-indanedione in an ionic liquid as a catalyst at room temperature. The applied synthetic route has the advantages of easy work-up under mild reaction conditions presenting moderate yields and an environmentally benign procedure. A theoretical study based on conceptual-density functional theory has been done, bond reactivity indices have been calculated and an electrophilic and nucleophilic character of localized orbitals has been determined to analyze the possible electronic mechanisms.

Photoinduced Proton Transfer Reactions for Mild O-H Functionalization Reactions of Unreactive Alcohols

2019 ◽  
Author(s):  
Sripati Jana ◽  
Zhen Yang ◽  
Fang Li ◽  
Claire Empel ◽  
Junming Ho ◽  
...  
Keyword(s):  
Photochemical Reaction ◽  
Transfer Reactions ◽  
Mechanistic Studies ◽  
Acid Base ◽  
Reaction Conditions ◽  
Proton Transfer Reactions ◽  
Photoinduced Proton Transfer ◽  
Broad Variety ◽  
Stoichiometric Reaction ◽  
Fluorinated Ethers

Hexafluoroisopropanol is typically considered as an unreactive solvent and not as a reagent in organic synthesis. Herein, we report on a mild and efficient photochemical reaction of aryl diazoacetates with hexafluoroisopropanol that enables, under stoichiometric reaction conditions, the synthesis of fluorinated ethers in excellent yield. We support these findings with mechanistic studies, which indicate a preorganization of hexafluoroisopropanol and the diazoalkane as an unreactive Lewis Acid-Base adduct. Only upon photoexcitation, this adduct undergoes a protonation-substitution reaction to the reaction product. We conclude with investigations on the applicability of this photochemical transformation and could show that a broad variety of acidic alcohols can be subjected to this transformation and thus demonstrate the feasibility of this concept in O-H functionalization reactions (52 examples, up to 98% yield).

Photoinduced Proton Transfer Reactions for Mild O-H Functionalization Reactions of Unreactive Alcohols

2019 ◽  
Author(s):  
Sripati Jana ◽  
Zhen Yang ◽  
Fang Li ◽  
Claire Empel ◽  
Junming Ho ◽  
...  
Keyword(s):  
Photochemical Reaction ◽  
Transfer Reactions ◽  
Mechanistic Studies ◽  
Acid Base ◽  
Reaction Conditions ◽  
Proton Transfer Reactions ◽  
Photoinduced Proton Transfer ◽  
Broad Variety ◽  
Stoichiometric Reaction ◽  
Fluorinated Ethers

Hexafluoroisopropanol is typically considered as an unreactive solvent and not as a reagent in organic synthesis. Herein, we report on a mild and efficient photochemical reaction of aryl diazoacetates with hexafluoroisopropanol that enables, under stoichiometric reaction conditions, the synthesis of fluorinated ethers in excellent yield. We support these findings with mechanistic studies, which indicate a preorganization of hexafluoroisopropanol and the diazoalkane as an unreactive Lewis Acid-Base adduct. Only upon photoexcitation, this adduct undergoes a protonation-substitution reaction to the reaction product. We conclude with investigations on the applicability of this photochemical transformation and could show that a broad variety of acidic alcohols can be subjected to this transformation and thus demonstrate the feasibility of this concept in O-H functionalization reactions (52 examples, up to 98% yield).

Acyl transfer reactions of carbohydrates, alcohols, phenols, thiols and thiophenols under green reaction conditions

RSC Advances ◽  
2015 ◽  
Vol 5 (15) ◽  
pp. 11687-11696 ◽  
Author(s):  
Santosh Kumar Giri ◽  
K. P. Ravindranathan Kartha
Keyword(s):  
Room Temperature ◽  
Catalytic Efficiency ◽  
Acyl Transfer ◽  
Transfer Reactions ◽  
Reaction Conditions ◽  
Methane Sulfonic Acid ◽  
Solvent Free Conditions ◽  
High Yields ◽  
Short Time ◽  
Acyl Transfer Reactions

Acyl transfer reactions of various carbohydrates, alcohols, phenols, thiols and thiophenols were achieved at room temperature in high yields and catalytic efficiency in the presence of methane sulfonic acid, a green organic acid, under solvent-free conditions over short time periods.

scholarly journals Synthesis of a copper-supported triplet nitrene complex pertinent to copper-catalyzed amination

Science ◽  
2019 ◽  
Vol 365 (6458) ◽  
pp. 1138-1143 ◽  
Author(s):  
Kurtis M. Carsch ◽  
Ida M. DiMucci ◽  
Diana A. Iovan ◽  
Alex Li ◽  
Shao-Liang Zheng ◽  
...  
Keyword(s):  
Multiple Bond ◽  
Transfer Reactions ◽  
Aryl Azides ◽  
Nitrene Transfer ◽  
Quantum Chemistry Calculations ◽  
Triplet Nitrene ◽  
X Ray Absorption ◽  
Dinitrogen Complex ◽  
Transfer Mechanisms ◽  
Bond Character

Terminal copper-nitrenoid complexes have inspired interest in their fundamental bonding structures as well as their putative intermediacy in catalytic nitrene-transfer reactions. Here, we report that aryl azides react with a copper(I) dinitrogen complex bearing a sterically encumbered dipyrrin ligand to produce terminal copper nitrene complexes with near-linear, short copper–nitrenoid bonds [1.745(2) to 1.759(2) angstroms]. X-ray absorption spectroscopy and quantum chemistry calculations reveal a predominantly triplet nitrene adduct bound to copper(I), as opposed to copper(II) or copper(III) assignments, indicating the absence of a copper−nitrogen multiple-bond character. Employing electron-deficient aryl azides renders the copper nitrene species competent for alkane amination and alkene aziridination, lending further credence to the intermediacy of this species in proposed nitrene-transfer mechanisms.

Naturally Occurring Organic Acid-catalyzed Facile Diastereoselective Synthesis of Biologically Active (E)-3-(arylimino)indolin-2-one Derivatives in Water at Room Temperature

2019 ◽  
Vol 23 (16) ◽  
pp. 1778-1788 ◽  
Author(s):  
Gurpreet Kaur ◽  
Arvind Singh ◽  
Kiran Bala ◽  
Mamta Devi ◽  
Anjana Kumari ◽  
...  
Keyword(s):  
Room Temperature ◽  
Biologically Active ◽  
Environmentally Benign ◽  
Diastereoselective Synthesis ◽  
Substituted Anilines ◽  
Reaction Conditions ◽  
Naturally Occurring ◽  
Acid Catalyzed ◽  
Reaction Media ◽  
Column Chromatographic

A simple, straightforward and efficient method has been developed for the synthesis of (E)-3-(arylimino)indolin-2-one derivatives and (E)-2-((4-methoxyphenyl)imino)- acenaphthylen-1(2H)-one. The synthesis of these biologically-significant scaffolds was achieved from the reactions of various substituted anilines and isatins or acenaphthaquinone, respectively, using commercially available, environmentally benign and naturally occurring organic acids such as mandelic acid or itaconic acid as catalyst in aqueous medium at room temperature. Mild reaction conditions, energy efficiency, good to excellent yields, environmentally benign conditions, easy isolation of products, no need of column chromatographic separation and the reusability of reaction media are some of the significant features of the present protocol.

A Facile, Efficient and Selective Deprotection of P - Methoxy Benzyl Ethers Using Zinc (II) Trifluoromethanesulfonate

2019 ◽  
Vol 16 (12) ◽  
pp. 955-958
Author(s):  
Reddymasu Sireesha ◽  
Reddymasu Sreenivasulu ◽  
Choragudi Chandrasekhar ◽  
Mannam Subba Rao
Keyword(s):  
Room Temperature ◽  
Protecting Groups ◽  
Side Reactions ◽  
Reaction Conditions ◽  
Acid Sensitivity ◽  
Time Period ◽  
Protective Groups ◽  
Benzyl Ethers ◽  
Last Stage ◽  
Zinc Triflate

: Deprotection is significant and conducted over mild reaction conditions, in order to restrict any more side reactions with sensitive functional groups as well as racemization or epimerization of stereo center because the protective groups are often cleaved at last stage in the synthesis. P - Methoxy benzyl (PMB) ether appears unique due to its easy introduction and removal than the other benzyl ether protecting groups. A facile, efficient and highly selective cleavage of P - methoxy benzyl ethers was reported by using 20 mole% Zinc (II) Trifluoromethanesulfonate at room temperature in acetonitrile solvent over 15-120 min. time period. To study the generality of this methodology, several PMB ethers were prepared from a variety of substrates having different protecting groups and subjected to deprotection of PMB ethers using Zn(OTf)2 in acetonitrile. In this methodology, zinc triflate cleaves only PMB ethers without affecting acid sensitivity, base sensitivity and also chiral epoxide groups.

One-pot Synthesis of Pyrazolone Sulfones by Iodine-catalyzed Sulfenylation of Pyrazolones with Aryl Sulfonyl Hydrazides Followed by Oxidation in Water

2018 ◽  
Vol 15 (3) ◽  
pp. 380-387
Author(s):  
Xia Zhao ◽  
Xiaoyu Lu ◽  
Lipeng Zhang ◽  
Tianjiao Li ◽  
Kui Lu
Keyword(s):  
Double Bond ◽  
Efficient Method ◽  
Room Temperature ◽  
Sulfonyl Chloride ◽  
Antibacterial Activities ◽  
Oxidation Reactions ◽  
Reaction Conditions ◽  
One Pot ◽  
X Ray ◽  
Amide Form

Aim and Objective: Pyrazolone sulfones have been reported to exhibit herbicidal and antibacterial activities. In spite of their good bioactivities, only a few methods have been developed to prepare pyrazolone sulfones. However, the substrate scope of these methods is limited. Moreover, the direct sulfonylation of pyrazolone by aryl sulfonyl chloride failed to give pyrazolone sulfones. Thus, developing a more efficient method to synthesize pyrazolone sulfones is very important. Materials and Method: Pyrazolone, aryl sulphonyl hydrazide, iodine, p-toluenesulphonic acid and water were mixed in a sealed tube, which was heated to 100°C for 12 hours. The mixture was cooled to 0°C and m-CPBA was added in batches. The mixture was allowed to stir for 30 min at room temperature. The crude product was purified by silica gel column chromatography to afford sulfuryl pyrazolone. Results: In all cases, the sulfenylation products were formed smoothly under the optimized reaction conditions, and were then oxidized to the corresponding sulfones in good yields by 3-chloroperoxybenzoic acid (m-CPBA) in water. Single crystal X-ray analysis of pyrazolone sulfone 4aa showed that the major tautomer of pyrazolone sulfones was the amide form instead of the enol form observed for pyrazolone thioethers. Moreover, the C=N double bond isomerized to form an α,β-unsaturated C=C double bond. Conclusion: An efficient method to synthesize pyrazolone thioethers by iodine-catalyzed sulfenylation of pyrazolones with aryl sulfonyl hydrazides in water was developed. Moreover, this method was employed to synthesize pyrazolone sulfones in one-pot by subsequent sulfenylation and oxidation reactions.

Rh(III)-Catalyzed Olefination and Alkylation of Arenes with Maleimides: A Tunable Strategy for C(sp2)–H Functionalization

Synthesis ◽  
2021 ◽  
Author(s):  
Hongji Li ◽  
Wenjie Zhang ◽  
Xueyan Liu ◽  
Zhenfeng Tian
Keyword(s):  
Room Temperature ◽  
Functional Group ◽  
Reaction Conditions ◽  
Bond Functionalization ◽  
Alkylation Process ◽  
Coupling Partner

AbstractWe herein report a new nitrogen-directed Rh(III)-catalyzed C(sp2)–H bond functionalization of N-nitrosoanilines and azoxybenzenes with maleimides as a coupling partner, in which the olefination/alkylation process can be finely controlled at room temperature by variation of the reaction conditions. This method shows excellent functional group tolerance, and presents a mild access to the resulting olefination/alkylation products in moderate to good yields.

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