scholarly journals Electron-deficient pyridinium salts/thiourea cooperative catalyzed O-glycosylation via activation of O-glycosyl trichloroacetimidate donors

2017 ◽  
Vol 13 ◽  
pp. 2385-2395 ◽  
Author(s):  
Mukta Shaw ◽  
Yogesh Kumar ◽  
Rima Thakur ◽  
Amit Kumar
Keyword(s):  
Hydrogen Bonding ◽  
Catalytic System ◽  
Room Temperature ◽  
Pyridinium Salt ◽  
Pyridinium Salts ◽  
Thiourea Derivative ◽  
Reaction Conditions ◽  
Thiourea Derivatives ◽  
Wide Range

The glycosylation of O-glycosyl trichloroacetimidate donors using a synergistic catalytic system of electron-deficient pyridinium salts/aryl thiourea derivatives at room temperature is demonstrated. The acidity of the adduct formed by the 1,2-addition of alcohol to the electron-deficient pyridinium salt is increased in the presence of an aryl thiourea derivative as an hydrogen-bonding cocatalyst. This transformation occurs under mild reaction conditions with a wide range of O-glycosyl trichloroacetimidate donors and glycosyl acceptors to afford the corresponding O-glycosides in moderate to good yields with predictable selectivity. In addition, the optimized method is also utilized for the regioselective O-glycosylation by using a partially protected acceptor.

scholarly journals Synthesis and Crystallographic Characterization of X-Substituted 2,4-Dinitrophenyl-4′-phenylbenzenesulfonates

Chemistry ◽  
2020 ◽  
Vol 2 (2) ◽  
pp. 591-599
Author(s):  
Brock A. Stenfors ◽  
Richard J. Staples ◽  
Shannon M. Biros ◽  
Felix N. Ngassa
Keyword(s):  
Diffraction Data ◽  
Pyridinium Salt ◽  
Environmentally Benign ◽  
Pyridinium Salts ◽  
X Ray Diffraction ◽  
X Ray ◽  
Wide Range ◽  
Aqueous Environments ◽  
Aqueous Base

Treatment of 2,4-dinitrophenol with sulfonyl chlorides in the presence of pyridine results in the formation of undesired pyridinium salts. In non-aqueous environments, the formation of the insoluble pyridinium salt greatly affects the formation of the desired product. A facile method of producing the desired sulfonate involves the use of an aqueous base with a water-miscible solvent. Herein, we present the optimization of methods for the formation of sulfonates and its application in the production of desired x-substituted 2,4-dinitrophenyl-4′-phenylbenzenesulfonates. This strategy is environmentally benign and supports a wide range of starting materials. Additionally, the intermolecular interactions of these sulfonate compounds were investigated using single-crystal x-ray diffraction data.

Efficient Copper-Catalyzed Synthesis of Substituted Pyrazoles at Room Temperature

Synlett ◽  
2018 ◽  
Vol 29 (20) ◽  
pp. 2689-2692 ◽  
Author(s):  
Haifeng Wang ◽  
Xiangli Sun ◽  
Shuangling Zhang ◽  
Guanglu Liu ◽  
Chunjie Wang ◽  
...  
Keyword(s):  
Reaction Time ◽  
Catalytic System ◽  
Efficient Method ◽  
Room Temperature ◽  
Copper Catalyst ◽  
Condensation Reaction ◽  
Reaction Conditions ◽  
Short Reaction Time ◽  
Acid Catalyzed ◽  
Substituted Pyrazoles

An efficient method for the synthesis of pyrazoles through a copper-catalyzed condensation reaction has been developed. The new catalytic system not only maintained a broad substrate scope but was also active under acid-free reaction conditions, overcoming the conventional requirement for an acid-catalyzed system. Furthermore, the copper catalyst enabled this reaction to be performed at room temperature and in a short reaction time.

Water-Assisted Organocatalysis: An Enantioselective Green Protocol for the Henry Reaction

2013 ◽  
Vol 66 (6) ◽  
pp. 661 ◽  
Author(s):  
Prashant B. Thorat ◽  
Santosh V. Goswami ◽  
Wamanrao N. Jadhav ◽  
Sudhakar R. Bhusare
Keyword(s):  
Hydrogen Bonding ◽  
Room Temperature ◽  
Enantioselective Synthesis ◽  
Henry Reaction ◽  
Reaction Conditions ◽  
Green Protocol ◽  
Excellent Yield ◽  
Water As Solvent ◽  
Nitroaldol Reaction ◽  
Work Up

We report an enantioselective Henry (nitroaldol) reaction catalysed by an organocatalyst using water as solvent. The enantioselective synthesis of β-nitroalcohols was achieved by using a neutral chiral organocatalyst, through strong hydrogen bonding, which results in the formation of corresponding products in excellent yield and enantioselectivity at room temperature. Other attractive features of the method are the eco-friendly, non-hazardous, and mild reaction conditions, inexpensive catalyst, and simple work up conditions.

Synthesis of bis-spiropiperidines using nano-CuFe2O4@chitosan as a robust and retrievable heterogeneous catalyst

2017 ◽  
Vol 41 (7) ◽  
pp. 416-419 ◽  
Author(s):  
Javad Safaei-Ghomi ◽  
Mohammad Rasool Lashkari ◽  
Hossein Shahbazi-Alavi
Keyword(s):  
Heterogeneous Catalyst ◽  
Aromatic Amine ◽  
Room Temperature ◽  
Barbituric Acid ◽  
Catalyst Loading ◽  
Reaction Conditions ◽  
One Pot ◽  
Wide Range ◽  
One Pot Condensation

An efficient pseudo six-component synthesis of bis-spiropiperidines is described by one-pot condensation of formaldehyde, aromatic amine and dimedone or N,N-dimethyl-barbituric acid using nano-CuFe2O4@chitosan at room temperature. This method provides several advantages including mild reaction conditions, applicability to wide range of substrates, reusability of the catalyst and little catalyst loading.

Infrared spectra of the ammonium ion in crystals. Part XII. Low-temperature transitions in ammonium dichromate, (NH4)2Cr2O7

1982 ◽  
Vol 60 (15) ◽  
pp. 1972-1977
Author(s):  
Gábor Keresztury ◽  
Osvald Knop ◽  
Michael Falk
Keyword(s):  
Hydrogen Bonding ◽  
Infrared Spectra ◽  
Room Temperature ◽  
Abundance Ratio ◽  
Ammonium Ion ◽  
Ammonium Ions ◽  
Hydrogen Bonding Interactions ◽  
Wide Range ◽  
Ammonium Dichromate ◽  
The Difference

Examination of the infrared spectra of the probe ions NH3D+ and NHD3+ in ammonium dichromate confirms the existence of the lowest (Ttr ~ 125 K) of the three transitions that are known, from nonspectroscopic evidence, to occur in this crystal below room temperature. Below Ttr the ammonium ions are of two types, in an abundance ratio of 1:1 and both of symmetry C1. Above Ttr the probe ion spectra are difficult to interpret in detail. The strength of the hydrogen-bonding interactions covers a wide range, as indicated by the difference between the highest and the lowest values of the isotopically isolated ND stretching frequencies at 10 K, 2392 and 2234 cm−1.

scholarly journals Sustainable Hydrogenation of Vinyl Derivatives Using Pd/C Catalysts

Catalysts ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 179
Author(s):  
Roman M. Mironenko ◽  
Elina R. Saybulina ◽  
Liudmila N. Stepanova ◽  
Tatiana I. Gulyaeva ◽  
Mikhail V. Trenikhin ◽  
...  
Keyword(s):  
Molecular Hydrogen ◽  
Room Temperature ◽  
Reaction Conditions ◽  
Liquid Phase Hydrogenation ◽  
Wide Range ◽  
Hydrogenation Reactions ◽  
The Stability ◽  
Vinyl Group ◽  
Vinyl Derivatives ◽  
Hydrogenation Selectivity

The hydrogenation of unsaturated double bonds with molecular hydrogen is an efficient atom-economic approach to the production of a wide range of fine chemicals. In contrast to a number of reducing reagents typically involved in organic synthesis, hydrogenation with H2 is much more sustainable since it does not produce wastes (i.e., reducing reagent residues). However, its full sustainable potential may be achieved only in the case of easily separable catalysts and high reaction selectivity. In this work, various Pd/C catalysts were used for the liquid-phase hydrogenation of O-, S-, and N-vinyl derivatives with molecular hydrogen under mild reaction conditions (room temperature, pressure of 1 MPa). Complete conversion and high hydrogenation selectivity (>99%) were achieved by adjusting the type of Pd/C catalyst. Thus, the proposed procedure can be used as a sustainable method for vinyl group transformation by hydrogenation reactions. The discovery of the stability of active vinyl functional groups conjugated with heteroatoms (O, S, and N) under hydrogenation conditions over Pd/C catalysts opens the way for many useful transformations.

Mild, General, and Regioselective Synthesis of 2-Aminopyridines from Pyridine N-Oxides via N-(2-Pyridyl)pyridinium Salts

Synlett ◽  
2022 ◽  
Author(s):  
Hui Xiong ◽  
Adam T. Hoye
Keyword(s):  
Reaction Mechanism ◽  
Functional Groups ◽  
Pyridinium Salt ◽  
Regioselective Synthesis ◽  
Pyridinium Salts ◽  
Reaction Sequence ◽  
Sequence Features ◽  
Hydrolytic Decomposition ◽  
Wide Range ◽  
15N Labeling

AbstractA synthesis of 2-aminopyridines from pyridine N-oxides via their corresponding N-(2-pyridyl)pyridinium salts has been demonstrated and investigated. The reaction sequence features a highly regioselective conversion of the N-oxide into its pyridinium salt followed by hydrolytic decomposition of the pyridinium moiety to furnish the 2-aminopyridine product. The method is compatible with a wide range of functional groups, is scalable, and features inexpensive reagents. 15N-labeling results gave products consistent with a Zincke reaction mechanism.

Direct use of allylic alcohols and allylic amines in palladium-catalyzed allylic amination

2017 ◽  
Vol 53 (37) ◽  
pp. 5151-5154 ◽  
Author(s):  
Jiangyan Jing ◽  
Xiaohong Huo ◽  
Jiefeng Shen ◽  
Jingke Fu ◽  
Qinghua Meng ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Functional Groups ◽  
Catalytic System ◽  
Allylic Alcohols ◽  
Allylic Amines ◽  
Allylic Amination ◽  
Reaction Conditions ◽  
Wide Range ◽  
Palladium Catalyzed ◽  
Direct Use

Allylic alcohols and allylic amines were directly utilized in a Pd-catalyzed hydrogen-bond-activated allylic amination under mild reaction conditions in the absence of any additives. The catalytic system is compatible with a variety of functional groups and can be used to prepare a wide range of linear allylic amines in good to excellent yields.

scholarly journals Acetate Facilitated Nickel Catalyzed Coupling of Aryl Chlorides and Alkyl Thiols

2021 ◽  
Author(s):  
Regina M. Oechsner ◽  
J. Philipp Wagner ◽  
Ivana Fleischer
Keyword(s):  
Catalytic System ◽  
Room Temperature ◽  
Low Cost ◽  
Potassium Acetate ◽  
Addition Product ◽  
Catalytic Cycle ◽  
Nmr Studies ◽  
Aryl Chlorides ◽  
Wide Range ◽  
Tertiary Alkyl

We report a mild, fast and convenient catalytic system for the coupling of aryl chlorides with primary, secondary, as well as previously challenging tertiary alkyl thiols using an air-stable nickel(II) precatayst in combination with the low-cost base potassium acetate at room temperature. This new catalytic system tolerates a variety of functional groups and enables the generation of thioethers for a wide range of substrates, including pharmaceutical compounds in excellent yields. Chemoselec-tive functionalization of disubstituted substrates was demonstrated. Kinetic and NMR-studies, as well as DFT computations support a Ni(0)/Ni(II) catalytic cycle and identify the oxidative addition product as the resting state. Acetate coordination and subsequent acetate facilitated formation of a thiolate complex via internal deprotonation play a key role in the catalytic cycle.

Synthesis of Pyridine-Thioethers via Mono- and Tricationic Pyridinium Salts

2005 ◽  
Vol 60 (6) ◽  
pp. 683-687 ◽  
Author(s):  
Andreas Schmidt ◽  
Thorsten Mordhorst
Keyword(s):  
Nucleophilic Substitution ◽  
Room Temperature ◽  
Pyridinium Salts ◽  
Pyridinium Chloride ◽  
Reaction Conditions ◽  
Mild Conditions

On nucleophilic substitution with S-nucleophiles at room temperature, 1-(4-dimethylamino)- [2,3,5,6-tetrachloropyridin-4-yl]pyridinium chloride (2) yielded tetrachloro-4-sulfanylpyridines and 2,3,5-trichloro-4,6-disulfanylpyridines depending on the reaction conditions. Similarly, the tricationic (3,5-dichloropyridine-2,4,6-triyl)-1,1’,1”-tris[4-(dimethylamino)pyridinium] trichloride 3 was reacted with S-nucleophiles to give the corresponding 3,5-trichloro-2,4,6-trisulfanylpyridines under mild conditions.

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