scholarly journals Selective carboxylation of reactive benzylic C–H bonds by a hypervalent iodine(III)/inorganic bromide oxidation system

2018 ◽  
Vol 14 ◽  
pp. 1087-1094 ◽  
Author(s):  
Toshifumi Dohi ◽  
Shohei Ueda ◽  
Kosuke Iwasaki ◽  
Yusuke Tsunoda ◽  
Koji Morimoto ◽  
...  
Keyword(s):  
Organic Solvent ◽  
Carboxylic Acids ◽  
Hypervalent Iodine ◽  
Homolytic Cleavage ◽  
Radical Species ◽  
Direct Introduction ◽  
Mild Conditions ◽  
High Degree ◽  
Oxidation System

An oxidation system comprising phenyliodine(III) diacetate (PIDA) and iodosobenzene with inorganic bromide, i.e., sodium bromide, in an organic solvent led to the direct introduction of carboxylic acids into benzylic C–H bonds under mild conditions. The unique radical species, generated by the homolytic cleavage of the labile I(III)–Br bond of the in situ-formed bromo-λ3-iodane, initiated benzylic carboxylation with a high degree of selectivity for the secondary benzylic position.

Synthesis of O-Aroyl-N,N-dimethylhydroxylamines through Hypervalent Iodine-Mediated Amination of Carboxylic Acids with N,N-Dimethylformamide

Synthesis ◽  
2017 ◽  
Vol 49 (18) ◽  
pp. 4303-4308 ◽  
Author(s):  
Dong Li ◽  
Chuancheng Zhang ◽  
Qiang Yue ◽  
Zhen Xiao ◽  
Xianglan Wang ◽  
...  
Keyword(s):  
Carboxylic Acids ◽  
Room Temperature ◽  
Functional Group ◽  
Hypervalent Iodine ◽  
Electrophilic Amination ◽  
Mild Conditions

An efficient protocol for the synthesis of O-aroyl-N,N-dimethylhydroxylamines, which are important electrophilic amination reagents, is described. The reaction between carboxylic acids and N,N-dimethylformamide is mediated by hypervalent iodine and occurs under mild conditions at room temperature to give the desired products in good yields. The process shows good functional group compatibility and air and moisture tolerance.

Oxidative Cyclization of β,γ-Unsaturated Carboxylic Acids Using Hypervalent Iodine Reagents: An Efficient Synthesis of 4-Substituted Furan-2-ones

Synthesis ◽  
2017 ◽  
Vol 49 (13) ◽  
pp. 2907-2912 ◽  
Author(s):  
Kensuke Kiyokawa ◽  
Satoshi Minakata ◽  
Kenta Takemoto ◽  
Shunsuke Yahata ◽  
Takumi Kojima
Keyword(s):  
Organic Chemistry ◽  
Carboxylic Acids ◽  
Present Method ◽  
Medicinal Chemistry ◽  
Oxidative Cyclization ◽  
Hypervalent Iodine ◽  
Efficient Synthesis ◽  
Substitution Pattern ◽  
Unsaturated Carboxylic Acids

The oxidative cyclization of β-substituted β,γ-unsaturated carboxylic acids using a hypervalent iodine reagent to provide 4-substituted furan-2-one products, is reported. In this cyclization, the use of a highly electrophilic PhI(OTf)2, which is in situ prepared from PhI(OAc)2 and Me3SiOTf, is crucial. Depending on the substitution pattern at the α-position of the substrates, furan-2(5H)-ones or furan-2(3H)-ones are produced. Thus, the present method offers a useful tool for accessing various types of 4-substituted furan-2-ones that are important structural motifs in the field of organic chemistry and medicinal chemistry.

[bmim]PF6/KOH: A Recyclable Catalytic System for an Azide–Arylacetaldehyde [3 + 2] Cycloaddition

2017 ◽  
Vol 41 (11) ◽  
pp. 631-635
Author(s):  
Yuqin Jiang ◽  
Kai Wu ◽  
Xuxia Tan ◽  
Dandan Zhang ◽  
Wenpei Dong ◽  
...  
Keyword(s):  
Transition Metal ◽  
Organic Solvent ◽  
Catalytic System ◽  
Room Temperature ◽  
Reaction Medium ◽  
Metal Catalyst ◽  
Transition Metal Catalyst ◽  
Green Protocol ◽  
Mild Conditions

A fast and green protocol for the synthesis of 1,4-disubstituted 1,2,3-triazoles from azides and arylacetaldehydes at room temperature was developed using [bmim]PF6/KOH as the reaction medium. It was found that the in situ-generated carbene from [bmim]PF6/KOH acted as the catalyst. In the absence of a transition-metal catalyst and organic solvent, this azide–arylacetaldehyde [3 + 2] cycloaddition proceeds efficiently, with high levels of regioselectivity, broad range of substrates, excellent yields and simple operation under mild conditions.

scholarly journals Oxidative Annulation of Diphenylpropanamides via In Situ Hypervalent Iodine-Promoted Intramolecular C–N/C–O Bond Formation

SynOpen ◽  
2021 ◽  
Vol 05 (04) ◽  
pp. 327-334
Author(s):  
Zhi-Peng Liang ◽  
Ying-Xin Yu ◽  
Yang Wang ◽  
Zheng-Guang Wu ◽  
Yuan-Yuan Sun
Keyword(s):  
Functional Group ◽  
Bond Formation ◽  
Single Step ◽  
Hypervalent Iodine ◽  
Target Compound ◽  
Migration Process ◽  
Aryl Iodide ◽  
Mild Conditions ◽  
Straightforward Approach

AbstractAn aryl iodide catalyzed intramolecular oxidative transformation of diphenylpropanamide derivatives is described that can readily afford the C–N/C–O coupling products in a single step. The speed of the 1,3-aryl iodide migration process determines the diversity of target compound generation in this reaction. This straightforward approach can be performed with the use of inexpensive and readily available catalyst, transition-metal-free, mild conditions and good functional group tolerance.

Carbene and Photocatalyst-Catalyzed Decarboxylative Radical Coupling of Carboxylic Acids and Acyl Imidazoles to Form Ketones

2021 ◽  
Author(s):  
Shi-Chao Ren ◽  
Xing Yang ◽  
Bivas Mondal ◽  
Chengli Mou ◽  
Weiyi Tian ◽  
...  
Keyword(s):  
Carboxylic Acid ◽  
Carboxylic Acids ◽  
Radical Coupling ◽  
Mild Conditions ◽  
Two Component ◽  
Decarboxylative Coupling ◽  
Coupling Partner ◽  
Powerful Strategy ◽  
Operational Simplicity

Abstract The carbene and photocatalyst co-catalyzed radical coupling of acyl electrophile and a radical precursor is emerging as attractive method for ketone synthesis. However, previous reports mainly limited to prefunctionalized radical precursors and two-component coupling. Herein, an N-heterocyclic carbene and photocatalyst catalyzed decarboxylative radical coupling of carboxylic acids and acyl imidazoles is disclosed, in which the carboxylic acids were directly used as radical precursors. The acyl imidazoles could also be generated in situ by reaction of a carboxylic acid with CDI thus furnishing a formally decarboxylative coupling of two carboxylic acids. In addition, the reaction was successfully extended to three-component coupling by using alkene as a third coupling partner via a radical relay process. The mild conditions, operational simplicity, and use of carboxylic acids as the reacting partners make our method a powerful strategy for construction of complex ketones from readily available starting materials, and late-stage modification of natural products and medicines.

A High Angle, Double Tilting Cold Stage for the AEI EM7

1974 ◽  
Vol 32 ◽  
pp. 450-451
Author(s):  
P.R. Swann ◽  
A.E. Lloyd
Keyword(s):  
Habit Plane ◽  
Temperature Control ◽  
Tilt Angle ◽  
Cooling System ◽  
Thermal Drift ◽  
High Angle ◽  
Cold Stage ◽  
High Degree ◽  
Better Than

Figure 1 shows the design of a specimen stage used for the in situ observation of phase transformations in the temperature range between ambient and −160°C. The design has the following features a high degree of specimen stability during tilting linear tilt actuation about two orthogonal axes for accurate control of tilt angle read-out high angle tilt range for stereo work and habit plane determination simple, robust construction temperature control of better than ±0.5°C minimum thermal drift and transmission of vibration from the cooling system.

scholarly journals Practical Synthesis of 2-Iodosobenzoic Acid (IBA) without Contamination by Hazardous 2-Iodoxybenzoic Acid (IBX) under Mild Conditions

Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 1897
Author(s):  
Hideyasu China ◽  
Nami Kageyama ◽  
Hotaka Yatabe ◽  
Naoko Takenaga ◽  
Toshifumi Dohi
Keyword(s):  
Aqueous Solution ◽  
Room Temperature ◽  
Practical Method ◽  
Hypervalent Iodine ◽  
Mild Conditions ◽  
Sequential Procedures ◽  
Iodine Compounds ◽  
Practical Synthesis ◽  
Iodosobenzoic Acid ◽  
Lower Temperature

We report a convenient and practical method for the preparation of nonexplosive cyclic hypervalent iodine(III) oxidants as efficient organocatalysts and reagents for various reactions using Oxone® in aqueous solution under mild conditions at room temperature. The thus obtained 2-iodosobenzoic acids (IBAs) could be used as precursors of other cyclic organoiodine(III) derivatives by the solvolytic derivatization of the hydroxy group under mild conditions of 80 °C or lower temperature. These sequential procedures are highly reliable to selectively afford cyclic hypervalent iodine compounds in excellent yields without contamination by hazardous pentavalent iodine(III) compound.

scholarly journals Mechanically induced solvent-free esterification method at room temperature

RSC Advances ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 5080-5085
Author(s):  
Lei Zheng ◽  
Chen Sun ◽  
Wenhao Xu ◽  
Alexandr V. Dushkin ◽  
Nikolay Polyakov ◽  
...  
Keyword(s):  
Natural Products ◽  
Carboxylic Acids ◽  
Late Stage ◽  
Reaction Mechanisms ◽  
Room Temperature ◽  
Solvent Free ◽  
Mild Conditions

We have developed I2/KH2PO2 and KI/P(OEt)3 strategy syntheses of esters from carboxylic acids and alcohols through different reaction mechanisms. The advantages of present protocol: mild conditions and late-stage diversification of natural products.

scholarly journals The Fluoride Anion-Catalyzed Sulfurization of Thioketones with Elemental Sulfur Leading to Sulfur-Rich Heterocycles: First Sulfurization of Thiochalcones

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 822
Author(s):  
Grzegorz Mlostoń ◽  
Jakub Wręczycki ◽  
Katarzyna Urbaniak ◽  
Dariusz M. Bieliński ◽  
Heinz Heimgartner
Keyword(s):  
Elemental Sulfur ◽  
Fluoride Anion ◽  
Ring Size ◽  
Mild Conditions ◽  
Tetrabutylammonium Fluoride ◽  
Cesium Fluoride ◽  
Secondary Reactions ◽  
Derivatives Of

Fluoride anion was demonstrated as a superior activator of elemental sulfur (S8) to perform sulfurization of thioketones leading to diverse sulfur-rich heterocycles. Due to solubility problems, reactions must be carried out either in THF using tetrabutylammonium fluoride (TBAF) or in DMF using cesium fluoride (CsF), respectively. The reactive sulfurizing reagents are in situ generated, nucleophilic fluoropolysulfide anions FS(8−x)−, which react with the C=S bond according to the carbophilic addition mode. Dithiiranes formed thereby, existing in an equilibrium with the ring-opened form (diradicals/zwitterions) are key-intermediates, which undergo either a step-wise dimerization to afford 1,2,4,5-tetrathianes or an intramolecular insertion, leading in the case of thioxo derivatives of 2,2,4,4-tetramethylcyclobutane-1,3-dione to ring enlarged products. In reactions catalyzed by TBAF, water bounded to fluoride anion via H-bridges and forming thereby its stable hydrates is involved in secondary reactions leading, e.g., in the case of 2,2,4,4-tetramethyl-3-thioxocyclobutanone to the formation of some unexpected products such as the ring enlarged dithiolactone and ring-opened dithiocarboxylate. In contrast to thioketones, the fluoride anion catalyzed sulfurization of their α,β-unsaturated analogues, i.e., thiochalcones is slow and inefficient. However, an alternative protocol with triphenylphosphine (PPh3) applied as a catalyst, offers an attractive approach to the synthesis of 3H-1,2-dithioles via 1,5-dipolar electrocyclization of the in situ-generated α,β-unsaturated thiocabonyl S-sulfides. All reactions occur under mild conditions and can be considered as attractive methods for the preparation of sulfur rich heterocycles with diverse ring-size.

Hypervalent-Iodine Mediated One-Pot Synthesis of Isoxazolines and Isoxazoles bearing Difluoromethyl Phosphonate Moiety

2021 ◽  
Author(s):  
Romana Pajkert ◽  
Henryk Koroniak ◽  
Pawel Kafarski ◽  
Gerd Volker Roeschenthaler
Keyword(s):  
Nitrile Oxide ◽  
Dipolar Cycloaddition ◽  
Hypervalent Iodine ◽  
One Pot ◽  
One Pot Synthesis

A one-pot, regioselective 1,3-dipolar cycloaddition of in situ generated (diethoxyphosphoryl)difluoromethyl nitrile oxide toward selected alkenes and alkynes is reported. This protocol enables facile access to 3,5-disubstituted isoxazolines and isoxazoles bearing...

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