Month: April 2022

So far, in addition to halogen atoms, other non-metallic atoms can become part of the aromatic heterocycle, and the target ring system is still aromatic.Wang, Pu; He, Jun-Yao; Yin, Jiang-Feng researched the compound: 2-Amino-4,5-dihydrothiazole-4-carboxylic acid( cas:2150-55-2 ).Application In Synthesis of 2-Amino-4,5-dihydrothiazole-4-carboxylic acid.They published the article 《Enhanced biocatalytic production of L-cysteine by Pseudomonas sp. B-3 with in situ product removal using ion-exchange resin》 about this compound( cas:2150-55-2 ) in Bioprocess and Biosystems Engineering. Keywords: cysteine biocatalytic production Pseudomonas anion exchange resin. We’ll tell you more about this compound (cas:2150-55-2).

Bioconversion of DL-2-amino-Δ2-thiazoline-4-carboxylic acid (DL-ATC) catalyzed by whole cells of Pseudomonas sp. was successfully applied for the production of L-cysteine. It was found, however, like most whole-cell biocatalytic processes, the accumulated L-cysteine produced obvious inhibition to the activity of biocatalyst and reduced the yield. To improve L-cysteine productivity, an anion exchange-based in situ product removal (ISPR) approach was developed. Several anion-exchange resins were tested to select a suitable adsorbent used in the bioconversion of DL-ATC for the in situ removal of L-cysteine. The strong basic anion-exchange resin 201 × 7 exhibited the highest adsorption capacity for L-cysteine and low adsorption for DL-ATC, which is a favorable option. With in situ addition of 60 g L-1 resin 201 × 7, the product inhibition can be reduced significantly and 200 mmol L-1 of DL-ATC was converted to L-cysteine with 90.4 % of yield and 28.6 mmol L-1 h-1 of volumetric productivity. Compared to the bioconversion without the addition of resin, the volumetric productivity of L-cysteine was improved by 2.27-fold using ISPR method.

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Reference:
Pyrazine – Wikipedia,
Pyrazine | C4H4N2 – PubChem

The preparation of ester heterocycles mostly uses heteroatoms as nucleophilic sites, which are achieved by intramolecular substitution or addition reactions. Compound: 5-Amino-2-fluoropyridine( cas:1827-27-6 ) is researched.Quality Control of 5-Amino-2-fluoropyridine.Panov, Maxim S.; Voskresenska, Valentyna D.; Ryazantsev, Mikhail N.; Tarnovsky, Alexander N.; Wilson, R. Marshall published the article 《5-Azido-2-aminopyridine, a New Nitrene/Nitrenium Ion Photoaffinity Labeling Agent That Exhibits Reversible Intersystem Crossing between Singlet and Triplet Nitrenes》 about this compound( cas:1827-27-6 ) in Journal of the American Chemical Society. Keywords: azidodiethylaminopyridine nitrene nitrenium ion photoaffinity labeling agent reversible intersystem. Let’s learn more about this compound (cas:1827-27-6).

The photochem. of a new photoaffinity labeling (PAL) agent, 5-azido-2-(N,N-diethylamino)-pyridine, was studied in aprotic and protic solvents using femtosecond-to-microsecond transient absorption and product anal., in conjunction with ab initio multiconfigurational and multireference quantum chem. calculations The excited singlet S1 state is spectroscopically dark, whereas photoexcitation to higher-lying singlet excited S2 and S3 states drives the photochem. reaction toward a barrierless ultrafast relaxation path via two conical intersections to S1, where N2 elimination leads to the formation of the closed-shell singlet nitrene. The singlet nitrene undergoes intersystem crossing (ISC) to the triplet nitrene in aprotic and protic solvents as well as protonation to form the nitrenium ion. The ISC rate constants in aprotic solvents increase with solvent polarity, displaying a “”direct”” gap effect, whereas an “”inverse”” gap effect is observed in protic solvents. Transient absorption actinometry experiments suggest that a solvent-dependent fraction from 20% to 50% of nitrenium ions is generated on a time scale of a few tens of picoseconds. The closed-shell singlet and triplet nitrene are separated by a small energy gap in protic solvents. As a result, the unreactive triplet state nitrene undergoes delayed, thermally activated reverse ISC to reform the reactive closed-shell singlet nitrene, which subsequently protonates, forming the remaining fraction of nitrenium ions. The product studies demonstrate that the resulting nitrenium ion stabilized by the electron-donating 4-amino group yields the final cross-linked product with high, almost quant. efficiency. The enhanced PAL function of this new azide with respect to the widely applied 4-amino-3-nitrophenyl azide is discussed.

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Reference:
Pyrazine – Wikipedia,
Pyrazine | C4H4N2 – PubChem

Most of the natural products isolated at present are heterocyclic compounds, so heterocyclic compounds occupy an important position in the research of organic chemistry. A compound: 2150-55-2, is researched, SMILESS is O=C(C1N=C(N)SC1)O, Molecular C4H6N2O2SJournal, Article, ACS Omega called RECiQ: A Rapid and Easy Method for Determining Cyanide Intoxication by Cyanide and 2-Aminothiazoline-4-carboxylic Acid Quantification in the Human Blood Using Probe Electrospray Ionization Tandem Mass Spectrometry, Author is Hisatsune, Kazuaki; Murata, Tasuku; Ogata, Koretsugu; Hida, Minemasa; Ishii, Akira; Tsuchihashi, Hitoshi; Hayashi, Yumi; Zaitsu, Kei, the main research direction is forensic RECiQ ESIMSMS cyanide intoxication aminothiazolinecarboxylate blood biomarker.Application of 2150-55-2.

In this study, we developed a rapid and easy method to determine cyanide (CN) intoxication by quantification of CN and 2-aminothiazoline-4-carboxylic acid (ATCA), which is a new and reliable indicator of CN exposure, in the human blood using probe electrospray ionization tandem mass spectrometry (PESI/MS/MS) named RECiQ. For CN, we applied the previously reported one-pot derivatization method using 2,3-naphthalene-dialdehyde and taurine, which can directly derivatize CN in the blood. The anal. conditions of the CN derivatization were optimized as a 10 min reaction time at room temperature In contrast, ATCA could be directly detected in the blood by PESI/MS/MS. We developed quant. methods for the derivatized CN and ATCA using an internal standard method and validated them using quality control samples, demonstrating that the linearities of each calibration curve were greater than 0.995, and intra- and interday precisions and accuracies were 5.1-15 and 1.1-14%, resp. Moreover, the lower limit of detections for CN and ATCA were 42 and 43 ng/mL, resp. Finally, we applied RECiQ to three postmortem blood specimens obtained from victims of fire incidents, which resulted in the successful quantification of CN and ATCA in all samples. As PESI/MS/MS can be completed within 0.5 min, and the sample volume requirement of RECiQ is only 2μL of blood, these methods are useful not only for the rapid determination of CN exposure but also for the estimation of the CN intoxication levels during an autopsy.

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Reference:
Pyrazine – Wikipedia,
Pyrazine | C4H4N2 – PubChem

Wang, Xinmou; Chen, Yuming; Song, Hongjian; Liu, Yuxiu; Wang, Qingmin published an article about the compound: Ethyl oxazole-5-carboxylate( cas:118994-89-1,SMILESS:O=C(C1=CN=CO1)OCC ).Name: Ethyl oxazole-5-carboxylate. Aromatic heterocyclic compounds can be classified according to the number of heteroatoms or the size of the ring. The authors also want to convey more information about this compound (cas:118994-89-1) through the article.

Although compounds with a 2-(2-arylphenyl) benzoxazole motif are biol. important, there are only a few methods for synthesizing them. Herein, authors report an efficient method for synthesis of such compounds by means of cobalt-catalyzed C-H/C-H cross-coupling reactions. This method has a broad substrate scope and good tolerance for sensitive functional groups. In addition, authors demonstrate that introducing a heteroarene moiety to biphenyl compounds enhanced their antifungal activity.

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Reference:
Pyrazine – Wikipedia,
Pyrazine | C4H4N2 – PubChem

The three-dimensional configuration of the ester heterocycle is basically the same as that of the carbocycle. Compound: 2-Amino-4,5-dihydrothiazole-4-carboxylic acid(SMILESS: O=C(C1N=C(N)SC1)O,cas:2150-55-2) is researched.Application In Synthesis of 2-Amino-4,5-dihydrothiazole-4-carboxylic acid. The article 《LC-MS/MS method development and validation for quantitative analyses of 2-aminothiazoline-4-carboxylic acid – a new cyanide exposure marker in post mortem blood》 in relation to this compound, is published in Talanta. Let’s take a look at the latest research on this compound (cas:2150-55-2).

2-Aminothiazoline-4-carboxylic acid (ATCA) is a hydrogen cyanide metabolite that has been found to be a reliable biomarker of cyanide poisoning, because of its long-term stability in biol. material. There are several methods of ATCA determination; however, they are restricted to extraction on mixed mode cation exchange sorbents. To date, there has been no reliable method of ATCA determination in whole blood, the most frequently used material in forensic anal. This novel method for ATCA determination in post mortem specimen includes protein precipitation, and derivatization of interfering compounds and their later extraction with Et acetate. ATCA was quant. analyzed via HPLC-tandem mass spectrometry with pos. electrospray ionization detection using a hydrophilic interaction liquid chromatog. column. The method satisfied all validation criteria and was tested on the real samples with satisfactory results. Therefore, this anal. approach has been proven to be a tool for measuring endogenous levels of ATCA in post mortem specimens. To conclude, a novel, accurate and sensitive method of ATCA determination in post mortem blood was developed. The establishment of the method provides new possibilities in the field of forensic science.

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Reference:
Pyrazine – Wikipedia,
Pyrazine | C4H4N2 – PubChem

In organic chemistry, atoms other than carbon and hydrogen are generally referred to as heteroatoms. The most common heteroatoms are nitrogen, oxygen and sulfur. Now I present to you an article called The stability of L-ATC hydrolase participating in L-cysteine production, published in 1995-03-31, which mentions a compound: 2150-55-2, mainly applied to aminothiazolinecarboxylate hydrolase stabilization cysteine manufacture, Application In Synthesis of 2-Amino-4,5-dihydrothiazole-4-carboxylic acid.

In the production of L-cysteine from DL-2-amino-Δ2-thiazoline-4-carboxylic acid (DL-ATC), the stability of the relevant enzymes produced by Pseudomonas sp. was tested, and strategies to improve the stability of L-ATC hydrolase were investigated with respect to water activity and ionic strength. Among the 3 enzymes which participate in L-cysteine production, i.e., ATC racemase, L-ATC hydrolase, and S-carbamyl-L-cysteine hydrolase, L-ATC hydrolase is the least stable. Various mixtures of salts and sorbitol were added to adjust the water activities of the tested solutions As the water activity decreased from 0.93 to 0.80, the stability of L-ATC hydrolase was sharply enhanced. In the absence of sorbitol, the stability of L-ATC hydrolase increased in proportion to ionic strength. Even though enzyme stability was not good at a low ionic strength, it was enhanced by lowering the water activity with the addition of sorbitol. The half-life of L-ATC hydrolase in sorbitol-salt mixtures increased by 10- to 20-fold compared to that of a control.

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Reference:
Pyrazine – Wikipedia,
Pyrazine | C4H4N2 – PubChem

In general, if the atoms that make up the ring contain heteroatoms, such rings become heterocycles, and organic compounds containing heterocycles are called heterocyclic compounds. An article called Probing the effects of pyrimidine functional group switches on acyclic fleximer analogues for antiviral activity, published in 2019, which mentions a compound: 591-54-8, Name is 4-Aminopyrimidine, Molecular C4H5N3, Formula: C4H5N3.

Due to their ability to inhibit viral DNA or RNA replication, nucleoside analogs have been used for decades as potent antiviral therapeutics. However, one of the major limitations of nucleoside analogs is the development of antiviral resistance. In that regard, flexible nucleoside analogs known as “”fleximers”” have garnered attention over the years due to their ability to survey different amino acids in enzyme binding sites, thus overcoming the potential development of antiviral resistance. Acyclic fleximers have previously demonstrated antiviral activity against numerous viruses including Middle East Respiratory Syndrome coronavirus (MERS-CoV), Ebola virus (EBOV), and, most recently, flaviviruses such as Dengue (DENV) and Yellow Fever Virus (YFV). Due to these interesting results, a Structure Activity Relationship (SAR) study was pursued in order to analyze the effect of the pyrimidine functional group and acyl protecting group on antiviral activity, cytotoxicity, and conformation. The results of those studies are presented herein.

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Reference:
Pyrazine – Wikipedia,
Pyrazine | C4H4N2 – PubChem

The three-dimensional configuration of the ester heterocycle is basically the same as that of the carbocycle. Compound: 5-Amino-2-fluoropyridine(SMILESS: NC1=CN=C(C=C1)F,cas:1827-27-6) is researched.Computed Properties of C4H6N2O2S. The article 《Synthesis and in vitro evaluation of [18F]BMS-754807: A potential PET ligand for IGF-1R》 in relation to this compound, is published in Bioorganic & Medicinal Chemistry Letters. Let’s take a look at the latest research on this compound (cas:1827-27-6).

Radiosynthesis and in vitro evaluation of [18F](S)-1-(4-((5-cyclopropyl-1H-pyrazol-3-yl)amino)pyrrolo[2,1-f][1,2,4]triazin-2-yl)-N-(6-fluoropyridin-3-yl)-2-methylpyrrolidine-2-carboxamide ([18F]BMS-754807 or [18F] I) a specific IGF-1R inhibitor was performed. [18F]I demonstrated specific binding in vitro to human cancer tissues. Synthesis of reference standard II(X= F) and corresponding bromo derivative II(X = X = Br), the precursor for radiolabeling were achieved from 2,4-dichloropyrrolo[2,1-f][1,2,4]triazine in three steps with 50% overall yield. The radioproduct was obtained in 8% yield by reacting 1a with [18F]TBAF in DMSO at 170 °C at high radiochem. purity and specific activity (1-2 Ci/μmol, N = 10). The proof of concept of IGF-IR imaging with [18F]I was demonstrated by in vitro autoradiog. studies using pathol. identified surgically removed grade IV glioblastoma, breast cancer and pancreatic tumor tissues. These studies indicate that [18F]I can be a potential PET tracer for monitoring IGF-1R.

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Reference:
Pyrazine – Wikipedia,
Pyrazine | C4H4N2 – PubChem

Computed Properties of C4H6N2O2S. The reaction of aromatic heterocyclic molecules with protons is called protonation. Aromatic heterocycles are more basic than benzene due to the participation of heteroatoms. Compound: 2-Amino-4,5-dihydrothiazole-4-carboxylic acid, is researched, Molecular C4H6N2O2S, CAS is 2150-55-2, about Enzymatic syntheses of L-cysteine by sodium alginate/gelatin co-immobilized Pseudomonas sp. B-3. Author is Wang, Pu; Yin, Jiangfeng; He, Junyao; Liang, Fayong.

The immobilization of Pseudomonas sp. B-3 by sodium alginate/gelatin mixed gel and the biosynthesis of L-cysteine from DL-2-amino-Δ2-thiazoline-4-carboxylic acid (DL-ATC) by immobilized cells were investigated. Suitable method for the immobilization of Pseudomonas sp. B-3 was selected by the comparison of eight immobilization methods. The influences of some key factors such as gel constitution, cells embedded and activation time on enzyme activity were optimized. Tween-60, N-carbamyl-L-cysteine amidohydrolase (L-NCC hydrolase) activator of Mn2+ and L-cysteine desulfhydrase inhibitor of hydroxylamine was added into reaction solution to improve L-cysteine productivity. Sodium alginate/gelatin co-immobilization showed both the highest enzyme activity and best gel strength. After 10 h activation for immobilized cells, the bioconversion was conducted at pH 8.0 and 42° for 10 h, 9.18 g/L-1 of L-cysteine was formed from 20 g/L-1 of DL-ATC/3H2O, with the molar conversion rate of 75.83%. An increase of 29.0% for L-cysteine production was obtained after catalyzed by immobilized cells in comparison with resting cells. After reused for four times, the relative molar conversion rate of L-cysteine remained 71.5% of the initial value. Sodium alginate/gelatin embedding method was suitable for immobilization of Pseudomonas sp. B-3. L-cysteine production was enhanced by the addition of Tween-60, Mn2+ and hydroxylamine hydrochloride in reaction solution

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Reference:
Pyrazine – Wikipedia,
Pyrazine | C4H4N2 – PubChem

Ren, Ji-Wei; Tong, Meng-Nan; Zhao, Yu-Fen; Ni, Feng published the article 《Synthesis of Dipeptide, Amide, and Ester without Racemization by Oxalyl Chloride and Catalytic Triphenylphosphine Oxide》. Keywords: dipeptide preparation diastereoselective; amino acid ester amidation triphenylphosphine oxide catalyst; ester preparation enantioselective; amide preparation enantioselective diastereoselective; amine phenylpropanoic acid amidation triphenylphosphine oxide catalyst; alc amino acid esterification triphenylphosphine oxide catalyst.They researched the compound: 4-Aminopyrimidine( cas:591-54-8 ).Application In Synthesis of 4-Aminopyrimidine. Aromatic heterocyclic compounds can be divided into two categories: single heterocyclic and fused heterocyclic. In addition, there is a lot of other information about this compound (cas:591-54-8) here.

An efficient triphenylphosphine oxide-catalyzed amidation and esterification for the rapid synthesis of a series of dipeptides ((2S,2S)/(2S,2R))-RNHCH(R1)C(O)N(R2)CH(C(O)OR3)R4 [R = (tert-butoxy)carbonyl, (9H-fluoren-9-ylmethoxy)carbonyl, (benzyloxy)carbonyl; R1 = Me, Bn, [(acetamidomethyl)sulfanyl]methyl, (tert-butoxy)methyl, etc.; R2 = H; R3 = Me, t-Bu; R4 = 2-methylpropyl, propan-2-yl, Bn; R2R4 = -(CH2)3-], amides (S)-R5N(R6)C(O)C(R7)(CH3)C6H5 (R5 = 2-methylpropyl, 3,4-dicyanophenyl, pyridin-4-yl, 1-(tert-butoxy)-1-oxo-3-phenylpropan-2-yl, etc.; R6 = H; R5R6 = -(CH2)2N(Boc)(CH2)2-; R7 = H, Me) and esters (S)-(Fmoc)NHCH(R1)C(O)OR8 (R1 = Me, Bn; R8 = Me, Ph, cyclohexyl, etc.) is described. This reaction is applicable to challenging couplings of hindered carboxylic acids (S)-RNHCH(R1)C(O)OH, C6H5C(CH3)(R7)C(O)OH, and (S)-(Fmoc)NHCH(R1)C(O)OH with weakly nucleophilic amines ((S)/(R))-NH(R2)CH(C(O)OR3)R4, R5NH(R6) or alcs., R8OH giving the products in good yields (67-90%) without racemization. This system employs the highly reactive intermediate Ph3PCl2 as the activator of the carboxylate in a catalytic manner and drives the reaction to completion in a short reaction time (less than 10 min).

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Reference:
Pyrazine – Wikipedia,
Pyrazine | C4H4N2 – PubChem