Day: January 6, 2023

Ring-Closing Metathesis Reactions: Interpretation of Conversion-Time Data was written by Thiel, Vasco;Wannowius, Klaus-Juergen;Wolff, Christiane;Thiele, Christina M.;Plenio, Herbert. And the article was included in Chemistry – A European Journal in 2013.Reference of 85838-94-4 This article mentions the following:

Conversion-time data were recorded for various ring-closing metathesis (RCM) reactions that lead to five- or six-membered cyclic olefins by using different precatalysts of the Hoveyda type. Slowly activated precatalysts were found to produce more RCM product than rapidly activated complexes, but this comes at the price of slower product formation. A kinetic model for the anal. of the conversion-time data was derived, which is based on the conversion of the precatalyst (Pcat) into the active species (Acat), with the rate constant k_act, followed by two parallel reactions: (1) the catalytic reaction, which utilizes Acat to convert reactants into products, with the rate k_cat, and (2) the conversion of Acat into the inactive species (Dcat), with the rate k_dec. The calculations employ two exptl. parameters: the concentration of the substrate (c(S)) at a given time and the rate of substrate conversion (-dc(S)/dt). This provides a direct measure of the concentration of Acat and enables the calculation of the pseudo-first-order rate constants k_act, k_cat, and k_dec and of k_S (for the RCM conversion of the resp. substrate by Acat). Most of the RCM reactions studied with different precatalysts are characterized by fast k_cat rates and by the k_dec value being greater than the k_act value, which leads to quasistationarity for Acat. The active species formed during the activation step was shown to be the same, regardless of the nature of different Pcats. The decomposition of Acat occurs along two parallel pathways, a unimol. (or pseudo-first-order) reaction and a bimol. reaction involving two ruthenium complexes. Electron-deficient precatalysts display higher rates of catalyst deactivation than their electron-rich relatives. Slowly initiating Pcats act as a reservoir, by generating small stationary concentrations of Acat. Based on this, it can be understood why the use of different precatalysts results in different substrate conversions in olefin metathesis reactions. In the experiment, the researchers used many compounds, for example, tert-Butyl 5,6-dihydropyridine-1(2H)-carboxylate (cas: 85838-94-4Reference of 85838-94-4).

tert-Butyl 5,6-dihydropyridine-1(2H)-carboxylate (cas: 85838-94-4) belongs to pyridine derivatives. The ring atoms in the pyridine molecule are sp2-hybridized. The nitrogen is involved in the π-bonding aromatic system using its unhybridized p orbital. The lone pair is in an sp2 orbital, projecting outward from the ring in the same plane as the σ bonds. One of the examples of pyridines is the well-known alkaloid lithoprimidine, which is an A3 adenosine receptor antagonist and N,N-dimethylaminopyridine (DMAP) analog, commonly used in organic synthesis.Reference of 85838-94-4

Referemce:
Pyridine – Wikipedia,
Pyridine | C5H5N – PubChem

Preparation of Tin Dioxide Nanoparticles by the Reverse Micelle Method: Experiment and Preliminary Calculations was written by Khalidova, M. M.;Voznesenskii, M. A.;Karpov, V. V.;Bobrysheva, N. P.;Osmolovskii, M. G.;Osmolovskaya, O. M.. And the article was included in Russian Journal of General Chemistry in 2018.Product Details of 104-73-4 This article mentions the following:

Synthetic and computational experiments were carried out to study the influence of the nature and structure of surfactants, and also of the reaction medium on the size of tin dioxide nanoparticles obtained by the reverse micelle method. In the experiment, the researchers used many compounds, for example, 1-Dodecylpyridin-1-ium bromide (cas: 104-73-4Product Details of 104-73-4).

1-Dodecylpyridin-1-ium bromide (cas: 104-73-4) belongs to pyridine derivatives. Pyridine has a dipole moment and a weaker resonant stabilization than benzene (resonance energy 117 kJ·mol−1 in pyridine vs. 150 kJ·mol−1 in benzene). Several pyridine derivatives play important roles in biological systems. While its biosynthesis is not fully understood, nicotinic acid (vitamin B3) occurs in some bacteria, fungi, and mammals.Product Details of 104-73-4

Referemce:
Pyridine – Wikipedia,
Pyridine | C5H5N – PubChem

Identification of an Oxalamide Ligand for Copper-Catalyzed C-O Couplings from a Pharmaceutical Compound Library was written by Chan, Vincent S.;Krabbe, Scott W.;Li, Changfeng;Sun, Lijie;Liu, Yue;Nett, Alex J.. And the article was included in ChemCatChem in 2019.Electric Literature of C6H7NO2 This article mentions the following:

The use of pharmaceutical compound library approach in combination with high throughput screening to identify N,N’-bis(thiophene-2-ylmethyl)oxalamide as a ligand that was generally effective for copper-catalyzed C-O cross-couplings to prepare both biarylethers as well as phenols under mild conditions. In the experiment, the researchers used many compounds, for example, 5-Hydroxy-2-methoxylpyridine (cas: 51834-97-0Electric Literature of C6H7NO2).

5-Hydroxy-2-methoxylpyridine (cas: 51834-97-0) belongs to pyridine derivatives. The ring atoms in the pyridine molecule are sp2-hybridized. The nitrogen is involved in the π-bonding aromatic system using its unhybridized p orbital. The lone pair is in an sp2 orbital, projecting outward from the ring in the same plane as the σ bonds. Several pyridine derivatives play important roles in biological systems. While its biosynthesis is not fully understood, nicotinic acid (vitamin B3) occurs in some bacteria, fungi, and mammals.Electric Literature of C6H7NO2

Referemce:
Pyridine – Wikipedia,
Pyridine | C5H5N – PubChem

Regioselective cyanation of 3-substituted pyridine 1-oxides was written by Fife, Wilmer K.. And the article was included in Heterocycles in 1984.Application of 89809-65-4 This article mentions the following:

N-Oxides I (R = H, Me, OMe, OH, Cl, cyano, CO₂Me) were converted to mixtures of nitriles II and III. I (R = Me) was treated with Me₃SiCN and Me₂NCOCl in CH₂Cl₂ to give 90% II (R = Me) and 10% III (R = Me). In the experiment, the researchers used many compounds, for example, Methyl 6-Cyanopyridine-3-carboxylate (cas: 89809-65-4Application of 89809-65-4).

Methyl 6-Cyanopyridine-3-carboxylate (cas: 89809-65-4) belongs to pyridine derivatives. Pyridine has a dipole moment and a weaker resonant stabilization than benzene (resonance energy 117 kJ·mol−1 in pyridine vs. 150 kJ·mol−1 in benzene). Pyridine derivatives are also useful as small-molecule α-helix mimetics that inhibit protein-protein interactions, as well as functionally selective GABA ligands.Application of 89809-65-4

Referemce:
Pyridine – Wikipedia,
Pyridine | C5H5N – PubChem

NMR studies of picolyl-type carbanions. VIII. Anions produced by reactions of alkyl-substituted pyridines with butyllithium was written by Konishi, Kazuyori;Matsumoto, Hiroshi;Saito, Katsuhiro;Takahashi, Kensuke. And the article was included in Bulletin of the Chemical Society of Japan in 1985.Product Details of 644-98-4 This article mentions the following:

¹H and ¹³C NMR spectra are reported for anions produced from methyl-, ethyl- and isopropylpyridines in THF. Two kinds of anions are formed concomitantly by Li-proton exchange and BuLi addition with 2-ethyl-, 2-isopropyl-, 4-methyl- and 4-ethylpyridines. The former reaction tends to occur at the substituent bonded to the position adjacent to N, and the latter occurs at an unsubstituted position adjacent to N. In the anions formed by the exchange from 2- and 4-ethylpyridines, a specific ring proton is coupled to the α-C atom, and, further, the o– or m-protons (or -C atoms) in the latter anion are nonequivalent at room temperature The α-carbons in these anions are virtually sp²-hybridized. In the experiment, the researchers used many compounds, for example, 2-Isopropylpyridine (cas: 644-98-4Product Details of 644-98-4).

2-Isopropylpyridine (cas: 644-98-4) belongs to pyridine derivatives. Pyridine’s the lone pair does not contribute to the aromatic system but importantly influences the chemical properties of pyridine, as it easily supports bond formation via an electrophilic attack. One of the examples of pyridines is the well-known alkaloid lithoprimidine, which is an A3 adenosine receptor antagonist and N,N-dimethylaminopyridine (DMAP) analog, commonly used in organic synthesis.Product Details of 644-98-4

Referemce:
Pyridine – Wikipedia,
Pyridine | C5H5N – PubChem

Inducing Axial Chirality in a Supramolecular Catalyst was written by Wenz, Katharina Marie;Leonhardt-Lutterbeck, Guenter;Breit, Bernhard. And the article was included in Angewandte Chemie, International Edition in 2018.Computed Properties of C5H3Br2NO This article mentions the following:

A new type of ligand, which is able to form axially chiral, supramol. complexes was designed using DFT calculations Two chiral monomers, each featuring a covalently bound chiral auxiliary, form a bidentate phosphine ligand with a twisted, hydrogen-bonded backbone upon coordination to a transition metal center which results in two diastereomeric, tropos complexes. The ratio of the diastereomers in solution is very temperature- and solvent-dependent. Rhodium and platinum complexes were analyzed through a combination of NMR studies, ESI-MS measurements, as well as UV-VIS and CD spectroscopy. The chiral self-organized ligands were evaluated in the rhodium-catalyzed asym. hydrogenation of α-dehydrogenated amino acids and resulted in good conversion and high enantioselectivity. This research opens the way for new ligand designs based on stereocontrol of supramol. assemblies through stereodirecting chiral centers. In the experiment, the researchers used many compounds, for example, 2,6-Dibromo-3-hydroxypyridine (cas: 6602-33-1Computed Properties of C5H3Br2NO).

2,6-Dibromo-3-hydroxypyridine (cas: 6602-33-1) belongs to pyridine derivatives. Pyridines are an important class of heterocycles and occur in polysubstituted forms in many naturally occurring biologically active compounds, drug molecules and chiral ligands. Pyridine derivatives are also useful as small-molecule α-helix mimetics that inhibit protein-protein interactions, as well as functionally selective GABA ligands.Computed Properties of C5H3Br2NO

Referemce:
Pyridine – Wikipedia,
Pyridine | C5H5N – PubChem

Kinetic study on the conversion of pyridine- and quinolinecarboxylic acids to the corresponding trichloromethyl compounds was written by Takahashi, Kazuyuki;Takeda, Koichi;Mitsuhashi, Keiryo. And the article was included in Journal of Heterocyclic Chemistry in 1978.Application of 3718-65-8 This article mentions the following:

The apparent 2nd order rate constant of the conversion of substituted picolinic and quinaldinic acids to the corresponding trichloromethylpyridines and quinolines by treatment with PCl₅ in refluxing SOCl₂ was measured. The logarithms of the rate constants (log k) are linear with the basicities (pKa) of the unsaturated ring nitrogens in the substrates. The reaction constant ρ was estimated In the experiment, the researchers used many compounds, for example, 3,5-Dimethylpyridine 1-oxide (cas: 3718-65-8Application of 3718-65-8).

3,5-Dimethylpyridine 1-oxide (cas: 3718-65-8) belongs to pyridine derivatives. In contrast to benzene, Pyridine’s electron density is not evenly distributed over the ring, reflecting the negative inductive effect of the nitrogen atom. Pyridine groups exist in countless molecules, and their applications include catalysis, drug design, molecular recognition, and natural product synthesis.Application of 3718-65-8

Referemce:
Pyridine – Wikipedia,
Pyridine | C5H5N – PubChem

Insight into the Interactions That Control the Phase Behaviour of New Aqueous Biphasic Systems Composed of Polyethylene Glycol Polymers and Ionic Liquids was written by Freire, Mara G.;Pereira, Jorge F. B.;Francisco, Maria;Rodriguez, Hector;Rebelo, Luis Paulo N.;Rogers, Robin D.;Coutinho, Joao A. P.. And the article was included in Chemistry – A European Journal in 2012.Safety of 1-Butyl-3-methylpyridinium Chloride This article mentions the following:

New polyethylene glycol (PEG)/ionic liquid aqueous biphasic systems (ABS) are presented. Distinct pairs of PEG polymers and ionic liquids can induce phase separation in aqueous media when dissolved at appropriate concentrations Phase diagrams have been determined for a large array of systems at 298, 308 and 323 K. A comparison of the binodal curves allowed the anal. of the tunable structural features of the ionic liquid (i.e., anionic nature, cationic core, cationic alkyl side chain length and functionalization, and number of alkyl substituents in the cation) and the influence of the mol. weight of the PEG polymer on the ability of these solutes to induce an ABS. It was observed that contrary to typical ABS based on ionic liquids and inorganic salts, in which the phase behavior is dominated by the formation of the hydration complexes of the ions, the interactions between the PEG polymers and ionic liquids control the phase demixing in the polymer-type ABS studied herein. It is shown that both the ionic liquids and PEG polymers can act as the salting-out species; i.e., it is an occurrence that is dependent on the structural features of the ionic liquid For the first time, PEG/ionic liquid ABS are reported and insight into the major interactions that govern the polymer/ionic liquid phase behavior in aqueous media are provided. The use of two different nonvolatile and tunable species (i.e., ionic liquids and PEG polymers) to form ABS allows the polarities of the phases to be tailored. Hence, the development of environmentally friendly separation processes that make use of these novel systems is envisaged. In the experiment, the researchers used many compounds, for example, 1-Butyl-3-methylpyridinium Chloride (cas: 125652-55-3Safety of 1-Butyl-3-methylpyridinium Chloride).

1-Butyl-3-methylpyridinium Chloride (cas: 125652-55-3) belongs to pyridine derivatives. In contrast to benzene, Pyridine’s electron density is not evenly distributed over the ring, reflecting the negative inductive effect of the nitrogen atom. Pyridine groups exist in countless molecules, and their applications include catalysis, drug design, molecular recognition, and natural product synthesis.Safety of 1-Butyl-3-methylpyridinium Chloride

Referemce:
Pyridine – Wikipedia,
Pyridine | C5H5N – PubChem

Selective Coupling of 1,2-Bis-Boronic Esters at the more Substituted Site through Visible-Light Activation of Electron Donor-Acceptor Complexes was written by Wang, Hui;Wu, Jingjing;Noble, Adam;Aggarwal, Varinder K.. And the article was included in Angewandte Chemie, International Edition in 2022.Computed Properties of C6H3FN2 This article mentions the following:

1,2-Bis-boronic esters are useful synthetic intermediates particularly as the two boronic esters can be selectively functionalized. Usually, the less hindered primary boronic ester reacts, but herein, we report a coupling reaction that enables the reversal of this selectivity. This is achieved through the formation of a boronate complex with an electron-rich aryllithium which, in the presence of an electron-deficient aryl nitrile, leads to the formation of an electron donor-acceptor complex. Following visible-light photoinduced electron transfer, a primary radical is generated which isomerizes to the more stable secondary radical before radical-radical coupling with the arene radical-anion, giving β-aryl primary boronic ester products. The reactions proceed under catalyst-free conditions. This method also allows stereodivergent coupling of cyclic cis-1,2-bis-boronic esters to provide trans-substituted products, complementing the selectivity observed in the Suzuki-Miyaura reaction. In the experiment, the researchers used many compounds, for example, 2-Fluoroisonicotinonitrile (cas: 3939-14-8Computed Properties of C6H3FN2).

2-Fluoroisonicotinonitrile (cas: 3939-14-8) belongs to pyridine derivatives. In contrast to benzene, Pyridine’s electron density is not evenly distributed over the ring, reflecting the negative inductive effect of the nitrogen atom. Many analogues of pyridine are known where N is replaced by other heteroatoms . Substitution of one C–H in pyridine with a second N gives rise to the diazine heterocycles (C4H4N2), with the names pyridazine, pyrimidine, and pyrazine.Computed Properties of C6H3FN2

Referemce:
Pyridine – Wikipedia,
Pyridine | C5H5N – PubChem

Regioselective C-H dithiocarbamation of indolizines with tetraalkylthiuram disulfide under metal-free conditions was written by Liu, Xiang;Song, Dan;Zhang, Zemin;Lin, Jiatong;Zhuang, Canzhan;Zhan, Haiying;Cao, Hua. And the article was included in Organic & Biomolecular Chemistry.Safety of 4-Methoxy-2-methylpyridine This article mentions the following:

An efficient and straightforward metal-free regioselective C-H dithiocarbamation of indolizines with tetraalkylthiuram disulfide has been described. A series of indolizine-dithiocarbamate derivatives, e.g., I (R¹ = H, 8-Br, 6-Et, 7-MeO, etc., R² = Ph, 3,4-Cl₂C₆H₃, 2-furyl, etc.), were easily accessed in moderate to good yields with a broad scope. In addition, imidazo[1,2-a]pyridines II (R¹ = H, 7-Me, R² = Ph, 3-FC₆H₄, 3-MeOC₆H₄) were also well tolerated to afford diverse imidazoheterocycle-dithiocarbamate products, which are expected to be utilized for drug discovery. Of note, the reaction could be readily scaled up, and shows its practical value in organic synthesis. In the experiment, the researchers used many compounds, for example, 4-Methoxy-2-methylpyridine (cas: 24103-75-1Safety of 4-Methoxy-2-methylpyridine).

4-Methoxy-2-methylpyridine (cas: 24103-75-1) belongs to pyridine derivatives. The pyridine ring occurs in many important compounds, including agrochemicals, pharmaceuticals, and vitamins. Many analogues of pyridine are known where N is replaced by other heteroatoms . Substitution of one C–H in pyridine with a second N gives rise to the diazine heterocycles (C4H4N2), with the names pyridazine, pyrimidine, and pyrazine.Safety of 4-Methoxy-2-methylpyridine

Referemce:
Pyridine – Wikipedia,
Pyridine | C5H5N – PubChem