A Multifunctional Reagent Designed for the Site-Selective Amination of Pyridines

2020 ◽  
Author(s):  
Patrick Fier ◽  
Suhong Kim ◽  
Ryan Cohen
Keyword(s):  
Reaction Mechanism ◽  
Direct Conversion ◽  
Single Step ◽  
The Novel ◽  
Title Reaction ◽  
Mild Conditions ◽  
Unique Reaction ◽  
Unexpected Findings ◽  
Site Selective

We report the development of a multifunctional reagent for the direct conversion of pyridines to Boc-protected 2-aminopyridines with exquisite site- and chemoselectivity. The novel reagent was prepared on 200 gram-scale in a single step, reacts in the title reaction under mild conditions without precautions towards air or moisture, and is tolerant of nearly all common functionality. Experimental and <i>in-situ </i>spectroscopic<i> </i>monitoring techniques provide detailed insights and unexpected findings for the unique reaction mechanism.

A Multifunctional Reagent Designed for the Site-Selective Amination of Pyridines

2020 ◽  
Author(s):  
Patrick Fier ◽  
Suhong Kim ◽  
Ryan Cohen
Keyword(s):  
Reaction Mechanism ◽  
Direct Conversion ◽  
Single Step ◽  
The Novel ◽  
Title Reaction ◽  
Mild Conditions ◽  
Unique Reaction ◽  
Unexpected Findings ◽  
Site Selective

We report the development of a multifunctional reagent for the direct conversion of pyridines to Boc-protected 2-aminopyridines with exquisite site- and chemoselectivity. The novel reagent was prepared on 200 gram-scale in a single step, reacts in the title reaction under mild conditions without precautions towards air or moisture, and is tolerant of nearly all common functionality. Experimental and <i>in-situ </i>spectroscopic<i> </i>monitoring techniques provide detailed insights and unexpected findings for the unique reaction mechanism.

Preparation of the Gold Nanoparticles and its Activity for Single-Step Amination of Benzene to Aniline

2013 ◽  
Vol 661 ◽  
pp. 47-52
Author(s):  
Gang Chen ◽  
Chun Hua Yang
Keyword(s):  
Gold Nanoparticles ◽  
Single Step ◽  
Xps Analysis ◽  
Deposition Method ◽  
Reaction Conditions ◽  
Catalyst Amount ◽  
Mild Conditions ◽  
Colloidal Deposition ◽  
Alumina Particles

Gold nanoparticles (AuNPs) were attached to the surface of alumina particles by an in-situ immobilizing method. SEM and XPS analysis showed that the coverage of alumina particles by AuNPs increased as the amount of alumina decreased; AuNPs onto alumina particles by the conventional colloidal deposition method were also prepared, whose TEM showed that the coverage of AuNPs was evidently smaller than that in the case of modified colloidal deposition method，although the AuNPs were spread almost uniformly over the surface of alumina particles. Au-immobilized alumina particles were subsequently utilized as the catalysts for direct amination of benzene with NH3H2O as an aminating agent and H2O2 as an oxidant under mild conditions. The reaction conditions were optimized: when catalyst amount was 2.0 g, reaction temperature was 50 °C, NH3H2O amount was 60 mL, H2O2 amount was 30 mL, and reaction time is 2 h, Au-immobilized alumina particles showed the highest aniline yield (1.96 mg) for 25 mL benzene.

scholarly journals Detection and Differentiation of Chlamydiae by Fluorescence In Situ Hybridization

2002 ◽  
Vol 68 (8) ◽  
pp. 4081-4089 ◽  
Author(s):  
Sven Poppert ◽  
Andreas Essig ◽  
Reinhard Marre ◽  
Michael Wagner ◽  
Matthias Horn
Keyword(s):  
In Situ Hybridization ◽  
Fluorescence In Situ Hybridization ◽  
Single Step ◽  
Detection Methods ◽  
The Novel ◽  
Antibody Staining ◽  
Uncultured Bacteria ◽  
Direct Fluorescence ◽  
Probe Set

ABSTRACT Chlamydiae are important pathogens of humans and animals but diagnosis of chlamydial infections is still hampered by inadequate detection methods. Fluorescence in situ hybridization (FISH) using rRNA-targeted oligonucleotide probes is widely used for the investigation of uncultured bacteria in complex microbial communities and has recently also been shown to be a valuable tool for the rapid detection of various bacterial pathogens in clinical specimens. Here we report on the development and evaluation of a hierarchic probe set for the specific detection and differentiation of chlamydiae, particularly C. pneumoniae, C. trachomatis, C. psittaci, and the recently described chlamydia-like bacteria comprising the novel genera Neochlamydia and Parachlamydia. The specificity of the nine newly developed probes was successfully demonstrated by in situ hybridization of experimentally infected amoebae and HeLa 229 cells, including HeLa 229 cells coinfected with C. pneumoniae and C. trachomatis. FISH reliably stained chlamydial inclusions as early as 12 h postinfection. The sensitivity of FISH was further confirmed by combination with direct fluorescence antibody staining. In contrast to previously established detection methods for chlamydiae, FISH was not susceptible to false-positive results and allows the detection of all recognized chlamydiae in one single step.

scholarly journals Chemoselective Union of Olefins, Organohalides and Redox-Active Esters Enables Regioselective Alkene Dialkylation

2020 ◽  
Author(s):  
Tao Yang ◽  
Yi Jiang ◽  
Yixin Luo ◽  
Yu Lan ◽  
Ming Joo Koh
Keyword(s):  
Complex Molecule ◽  
Single Step ◽  
Dft Studies ◽  
Organometallic Reagents ◽  
Mild Conditions ◽  
Chemistry Research ◽  
Alkyl Groups ◽  
Redox Active ◽  
Site Selectivity

<div>Multicomponent catalytic processes that can generate multiple C(sp<sup>3</sup>)-C(sp<sup>3</sup>) bonds in a single step under mild conditions,particularly if the catalysts and substrates are inexpensive, are highly sought-after in chemistry research for complex molecule synthesis. Here, we disclose an efficient Ni-catalysed reductive protocol that chemoselectively merges alkenyl amides with two different</div><div>aliphatic electrophiles. Starting materials are readily accessible from stable and abundant feedstock and products are furnished in up to >98:2 regioisomeric ratios. The present strategy eliminates the use of sensitive organometallic reagents, tolerates a wide array of complex functionalities and enables regiodivergent addition of two primary alkyl groups bearing similar electronic and steric attributes across aliphatic C=C bonds with exquisite control of site selectivity. Utility is underscored by the concise synthesis of bioactive compounds and post-reaction functionalizations leading to structurally diverse scaffolds. DFT studies revealed that the regiochemical outcome originates from the orthogonal reactivity and chemoselectivity profiles of in situ-generated organonickel species.</div>

scholarly journals ZIF-8 as a Catalyst in Ethylene Oxide and Propylene Oxide Reaction with CO2 to Cyclic Organic Carbonates

2019 ◽  
Vol 3 (3) ◽  
pp. 60 ◽  
Author(s):  
Jenny G. Vitillo ◽  
Valentina Crocellà ◽  
Francesca Bonino
Keyword(s):  
Onset Time ◽  
Direct Conversion ◽  
Co Catalyst ◽  
Mild Conditions ◽  
Carbonate Formation ◽  
Greenhouse Emissions ◽  
Organic Carbonates ◽  
In Situ Infrared Spectroscopy ◽  
And Storage

CO2 is an important by-product in epoxides synthesis, accounting for 0.02% of worldwide greenhouse emissions. The CO2 cycloaddition to ethylene and propylene oxides is an important class of reactions due to the versatile nature of the corresponding organic carbonates as chemical feedstocks. We report that these reactions can be catalyzed by ZIF-8 (Zeolitic Imidazole Framework-8) in the absence of solvent or co-catalyst and in mild conditions (40 °C and 750 mbar). In situ infrared spectroscopy places the onset time for ethylene and propylene carbonate formation to 80 and 30 min, respectively. Although there is low catalytic activity, these findings suggest the possibility to cut the CO2 emissions from epoxides production through their direct conversion to these highly valuable chemical intermediates, eliminating de facto energetically demanding steps as the CO2 capture and storage.

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.

scholarly journals Chemoselective Union of Olefins, Organohalides and Redox-Active Esters Enables Regioselective Alkene Dialkylation

2020 ◽  
Author(s):  
Tao Yang ◽  
Yi Jiang ◽  
Yixin Luo ◽  
Yu Lan ◽  
Ming Joo Koh
Keyword(s):  
Complex Molecule ◽  
Single Step ◽  
Dft Studies ◽  
Organometallic Reagents ◽  
Mild Conditions ◽  
Chemistry Research ◽  
Alkyl Groups ◽  
Redox Active ◽  
Site Selectivity

<div>Multicomponent catalytic processes that can generate multiple C(sp<sup>3</sup>)-C(sp<sup>3</sup>) bonds in a single step under mild conditions,particularly if the catalysts and substrates are inexpensive, are highly sought-after in chemistry research for complex molecule synthesis. Here, we disclose an efficient Ni-catalysed reductive protocol that chemoselectively merges alkenyl amides with two different</div><div>aliphatic electrophiles. Starting materials are readily accessible from stable and abundant feedstock and products are furnished in up to >98:2 regioisomeric ratios. The present strategy eliminates the use of sensitive organometallic reagents, tolerates a wide array of complex functionalities and enables regiodivergent addition of two primary alkyl groups bearing similar electronic and steric attributes across aliphatic C=C bonds with exquisite control of site selectivity. Utility is underscored by the concise synthesis of bioactive compounds and post-reaction functionalizations leading to structurally diverse scaffolds. DFT studies revealed that the regiochemical outcome originates from the orthogonal reactivity and chemoselectivity profiles of in situ-generated organonickel species.</div>

One-Pot Reaction To Form Hydrophosphorylated Fullerenes from C60 and Ph3–n PCl n /ROH

Synlett ◽  
2018 ◽  
Vol 29 (09) ◽  
pp. 1219-1222
Author(s):  
Nana Xin ◽  
Xiuying Xie ◽  
Chang-Qiu Zhao ◽  
Xianqiang Huang ◽  
Junhong Zhang ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Experimental Results ◽  
One Pot ◽  
Fullerene Derivatives ◽  
Mild Conditions ◽  
One Step ◽  
The One

Hydrophosphorylated fullerene derivatives were readily prepared in one step by treating C60 with Ph3– n PCl n (n = 1–3) and ROH (R = H, alkyl). The one-pot reaction could be performed under mild conditions with moderate to good yields. Dichlorophenylphosphine and alcohols exhibited unexpected reactivity towards C60. A possible reaction mechanism involving the formation of P(III)–OH in situ was proposed to explain the experimental results.

Direct incorporation of [ 18F] into aliphatic systems: A promising Mncatalysed labelling technique for PET imaging

2020 ◽  
Vol 13 ◽  
Author(s):  
Sara Cesarec ◽  
Jonathan A. Robson ◽  
Laurence S. Carroll ◽  
Eric O. Aboagye ◽  
Alan C. Spivey
Keyword(s):  
Positron Emission Tomography ◽  
Pet Imaging ◽  
Emission Tomography ◽  
Labelling Technique ◽  
Porphyrin Complex ◽  
Mild Conditions ◽  
Drug Substances ◽  
Positron Emission ◽  
Site Selective ◽  
Direct Incorporation

Background: One of the challenges in positron emission tomography (PET) is labelling complex aliphatic molecules. Objective: To develop a method of metal-catalysed radiofluorination that is site-selective and works in moderate to good yields under facile conditions. Methods: We report here on the optimisation of an aliphatic C-H to C-18F bond transformation catalysed by a Mn(porphyrin) complex. Results: The successful oxidation of 11 aliphatic molecules including progesterone are reported. Radiochemical Incorporations (RCIs) up to 69% were achieved within 60 min without the need for pre-activation or specialist equipment. Conclusion: The method features mild conditions (60 °C) and promises to constitute a valuable approach to labelling of biomolecules and drug substances.

scholarly journals Influence of protein (human galectin-3) design on aspects of lectin activity

2020 ◽  
Vol 154 (2) ◽  
pp. 135-153 ◽  
Author(s):  
Gabriel García Caballero ◽  
Donella Beckwith ◽  
Nadezhda V. Shilova ◽  
Adele Gabba ◽  
Tanja J. Kutzner ◽  
...  
Keyword(s):  
Protein Design ◽  
Full Range ◽  
Biological Information ◽  
The Novel ◽  
Modular Assembly ◽  
Binding Partners ◽  
Galectin 3 ◽  
Potential Applications ◽  
Similar Affinity

Abstract The concept of biomedical significance of the functional pairing between tissue lectins and their glycoconjugate counterreceptors has reached the mainstream of research on the flow of biological information. A major challenge now is to identify the principles of structure–activity relationships that underlie specificity of recognition and the ensuing post-binding processes. Toward this end, we focus on a distinct feature on the side of the lectin, i.e. its architecture to present the carbohydrate recognition domain (CRD). Working with a multifunctional human lectin, i.e. galectin-3, as model, its CRD is used in protein engineering to build variants with different modular assembly. Hereby, it becomes possible to compare activity features of the natural design, i.e. CRD attached to an N-terminal tail, with those of homo- and heterodimers and the tail-free protein. Thermodynamics of binding disaccharides proved full activity of all proteins at very similar affinity. The following glycan array testing revealed maintained preferential contact formation with N-acetyllactosamine oligomers and histo-blood group ABH epitopes irrespective of variant design. The study of carbohydrate-inhibitable binding of the test panel disclosed up to qualitative cell-type-dependent differences in sections of fixed murine epididymis and especially jejunum. By probing topological aspects of binding, the susceptibility to inhibition by a tetravalent glycocluster was markedly different for the wild-type vs the homodimeric variant proteins. The results teach the salient lesson that protein design matters: the type of CRD presentation can have a profound bearing on whether basically suited oligosaccharides, which for example tested positively in an array, will become binding partners in situ. When lectin-glycoconjugate aggregates (lattices) are formed, their structural organization will depend on this parameter. Further testing (ga)lectin variants will thus be instrumental (i) to define the full range of impact of altering protein assembly and (ii) to explain why certain types of design have been favored during the course of evolution, besides opening biomedical perspectives for potential applications of the novel galectin forms.

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