Day: April 12, 2022

The reaction of an aromatic heterocycle with a proton is called a protonation. One of articles about this theory is 《Nucleosides and nucleotides. XXX. Syntheses of 8-substituted guanosine derivatives》. Authors are Ikehara, Morio; Muneyama, Kei.The article about the compound:8-Bromoguaninecas:3066-84-0,SMILESS:NC(N1)=NC(NC(Br)=N2)=C2C1=O).Computed Properties of C5H4BrN5O. Through the article, more information about this compound (cas:3066-84-0) is conveyed.

cf. CA 64, 14255f. 8-Bromoguanosine (I) was converted to 8-mercaptoguanosine by the method of Holmes and Robins (CA 60, 14584c), and was methylated with methyl iodide to afford 8-methylthioguanosine (II). In addition, 8-ethylthioguanosine was obtained directly by reaction of I with ethyl mercaptide in ethanol. II was oxidized either with N-chlorosuccinimide or with H2O2 (H2O2, in limited amount, being preferable) to afford 8-(methylsulfonyl)guanosine (III). When III was heated at 80° in 0.1N HCl 4 hrs., 8-methylsulfonylguanine (IV) (but not an N-oxide derivative) was obtained. Treatment of III with 0.1N NaOH at 100° 3 hrs. also gave IV. When III was kept at 30° 40 hrs. in dimethyl sulfoxide with excess Na tert-butoxide, a substance having λ (H)+ 256, 284 mμ; λ(OH)- 286 mμ was obtained, accompanied by a small amount of IV. The former compound contained S and D-ribose moieties, and it was deduced from its uv properties that the guanosine ring in III had been cleaved. Its absorption could be explained if a bathochromic shift of approx. 10-20 mμ, which is generally observed by the substitution of a methyl sulfonyl group at the 8-position of guanosine, was added to the absorption spectra of 4-aminoimidazolecarboxamide 1-p-riboside (λ(H+) 267, 240 mμ; λ(OH-) 267 mμ). The pKa value of III (8.3) is much higher than that of guanosine (9.2-9.5). The easy dissociation of N’-H of III would render the pyrimidine ring more susceptible to the nucleophilic attack of tert-butoxide. Under similar reaction conditions guanosine did not react with tert-butoxide. When III was treated with Na methoxide in methanol at 130-50°, 8-methoxyguanosine was obtained, the structure of which was confirmed by comparison with a sample obtained from I. 8-Dimethylaminoguanosine was prepared by heating I with dimethylamine in methanol at 120-30° 5 hrs. It is concluded that nucleophilic substitution occurred smoothly in I, as expected in the case of aromatic halo compound activated by ο- or p-electron attracting groups. However, in the case of III the strong electron-attracting nature of the methylsulfonyl group at position 8 caused a nucleophilic attack on N1 or N3, and the subsequent cleavage of the pyrimidine ring. Moreover, acidic hydrolysis easily cleaved III at the glycosidic linkage, whereas 8-hydroxypurine D-ribonucleoside is resistant to such cleavage. 14 references.

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Tetrahydrofuran – Wikipedia,
Tetrahydrofuran | (CH2)3CH2O – PubChem

The reaction of an aromatic heterocycle with a proton is called a protonation. One of articles about this theory is 《Synthesis, antimicrobial, and anti-inflammatory activities of acetamido pyrrolyl azoles》. Authors are Sowmya, Donthamsetty V.; Basha, Shaik Sharafuddin; Devi, Palampalli Uma Maheswari; Lavanyalatha, Yerraguravagari; Padmaja, Adivireddy; Padmavathi, Venkatapuram.The article about the compound:Methyl 2-(1-methyl-1H-pyrrol-2-yl)acetatecas:51856-79-2,SMILESS:O=C(OC)CC1=CC=CN1C).Computed Properties of C8H11NO2. Through the article, more information about this compound (cas:51856-79-2) is conveyed.

Series of 2-(pyrrol-2-yl)-N-(oxazol-2-yl)acetamides I [R = H, Me, MeO, Cl, Br, NO2; X = O], 2-(pyrrol-2-yl)-N-(thiazol-2-yl)acetamides I [X = S] and 2-(pyrrol-2-yl)-N-(imidazol-2-yl)acetamides I [X = NH] were prepared via reaction of (5-benzoyl-1-methyl-1H-pyrrol-2-yl)acetic acid with 4-aryloxazol-2-amines/4-arylthiazol-2-amines/4-aryl-1H-imidazol-2-amines resp. All the synthesized compounds I were screened for their antibacterial, antifungal and anti-inflammatory activities. Among the tested compounds, 2-(pyrrol-2-yl)-N-(thiazol-2-yl)acetamides I [R = NO2; X = S] and 2-(pyrrol-2-yl)-N-(imidazol-2-yl)acetamides I [R = NO2; X = N] exhibited promising antibacterial activity against K. pneumoniae. The 2-(pyrrol-2-yl)-N-(imidazol-2-yl)acetamides I [R = NO2; X = N] showed good antifungal activity against P. chrysogenum and 2-(pyrrol-2-yl)-N-(oxazol-2-yl)acetamidesI [R = MeO; X = O] displayed potential anti-inflammatory activity.

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Tetrahydrofuran – Wikipedia,
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The preparation of ester heterocycles mostly uses heteroatoms as nucleophilic sites, which are achieved by intramolecular substitution or addition reactions. Compound: 2-Amino-5-chlorobenzaldehyde( cas:20028-53-9 ) is researched.Synthetic Route of C7H6ClNO.Liu, Hu; Tian, Ye; Lee, Kyungae; Krishnan, Pranav; Wang, May Kwang-Mei; Whelan, Sean; Mevers, Emily; Soloveva, Veronica; Dedic, Benjamin; Liu, Xinyong; Cunningham, James M. published the article 《Identification of Potent Ebola Virus Entry Inhibitors with Suitable Properties for in Vivo Studies》 about this compound( cas:20028-53-9 ) in Journal of Medicinal Chemistry. Keywords: adamantane dipeptide piperazine preparation antiviral Ebola virus NPC1 inhibitor. Let’s learn more about this compound (cas:20028-53-9).

Previous studies identified an adamantane dipeptide piperazine 3.47 that inhibits Ebola virus (EBOV) infection by targeting the essential receptor Niemann-Pick C1 (NPC1). The physicochem. properties of 3.47 limit its potential for testing in vivo. Optimization by improving potency, reducing hydrophobicity, and replacing labile moieties identified 3.47 derivatives with improved in vitro ADME properties that are also highly active against EBOV infection, including when tested in the presence of 50% normal human serum (NHS). In addition, 3A4 was identified as the major cytochrome P 450 isoform that metabolizes these compounds, and accordingly, mouse microsome stability was significantly improved when tested in the presence of the CYP3A4 inhibitor ritonavir that is approved for clin. use as a booster of anti-HIV drugs. Oral administration of the EBOV inhibitors with ritonavir resulted in a pharmacokinetic profile that supports a b.i.d. dosing regimen for efficacy studies in mice.

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Tetrahydrofuran – Wikipedia,
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Category: tetrahydrofurans. The mechanism of aromatic electrophilic substitution of aromatic heterocycles is consistent with that of benzene. Compound: 8-Bromoguanine, is researched, Molecular C5H4BrN5O, CAS is 3066-84-0, about Exploring the chemical space around 8-mercaptoguanine as a route to new inhibitors of the folate biosynthesis enzyme HPPK. Author is Chhabra, Sandeep; Barlow, Nicholas; Dolezal, Olan; Hattarki, Meghan K.; Newman, Janet; Peat, Thomas S.; Graham, Bim; Swarbrick, James D..

As the second essential enzyme of the folate biosynthetic pathway, the potential antimicrobial target, HPPK (6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase), catalyzes the Mg2+-dependant transfer of pyrophosphate from the cofactor (ATP) to the substrate, 6-hydroxymethyl-7,8-dihydropterin. Recently, we showed that 8-mercaptoguanine (8-MG) bound at the substrate site (KD ∼ 13 μM), inhibited the S. aureus enzyme (SaHPPK) (IC50 ∼ 41 μM) and determined the structure of the SaHPPK/8-MG complex. Here we present the synthesis of a series of guanine derivatives, together with their HPPK binding affinities, as determined by SPR and ITC anal. The binding mode of the most potent was investigated using 2D NMR spectroscopy and x-ray crystallog. The results indicate, firstly, that the SH group of 8-MG makes a significant contribution to the free energy of binding. Secondly, direct N9 substitution, or tautomerization arising from N7 substitution in some cases, leads to a dramatic reduction in affinity due to loss of a critical N9-H···Val46 hydrogen bond, combined with the limited space available around the N9 position. The water-filled pocket under the N7 position is significantly more tolerant of substitution, with a hydroxyl Et 8-MG derivative attached to N7 (compound 21a) exhibiting an affinity for the apo enzyme comparable to the parent compound (KD ∼ 12 μM). In contrast to 8-MG, however, 21a displays competitive binding with the ATP cofactor, as judged by NMR and SPR anal. The 1.85 Å x-ray structure of the SaHPPK/21a complex confirms that extension from the N7 position towards the Mg2+-binding site, which affords the only tractable route out from the pterin-binding pocket. Promising strategies for the creation of more potent binders might therefore include the introduction of groups capable of interacting with the Mg2+ centers or Mg2+-binding residues, as well as the development of bitopic inhibitors featuring 8-MG linked to a moiety targeting the ATP cofactor binding site.

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Tetrahydrofuran – Wikipedia,
Tetrahydrofuran | (CH2)3CH2O – PubChem

Product Details of 51856-79-2. 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. Compound: Methyl 2-(1-methyl-1H-pyrrol-2-yl)acetate, is researched, Molecular C8H11NO2, CAS is 51856-79-2, about An Electrophilic Approach to the Palladium-Catalyzed Carbonylative C-H Functionalization of Heterocycles.

A palladium-catalyzed approach to intermol. carbonylative C-H functionalization is described. This transformation is mediated by PtBu3-coordinated palladium catalyst and allows the derivatization of a diverse range of heterocycles, including pyrroles, indoles, imidazoles, benzoxazoles, and furans. Preliminary studies suggest that this reaction may proceed via the catalytic formation of highly electrophilic intermediates. Overall, this provides with an atom-economical and general synthetic route to generate aryl-(hetero)aryl ketones I (Y = O, NBn, NMe, NEt, etc.; Z = CH, N; R = H, 4-F, 3-Br, 2-Cl, 4-CO2Et, 4- CN, etc.) using stable reagents (aryl iodides and CO) and without the typical need to exploit pre-metalated heterocycles in carbonylative coupling chem.

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Tetrahydrofuran – Wikipedia,
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SDS of cas: 1028-33-7. 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: 1-Hexyl-3,7-dimethyl-1H-purine-2,6(3H,7H)-dione, is researched, Molecular C13H20N4O2, CAS is 1028-33-7, about Comparative intestinal absorption of a series of xanthines in aqueous or oil solutions. Author is Nook, T.; Doelker, E.; Buri, P..

The intestinal absorption of a group of xanthines from oil solutions was tested in rats by means of an in situ perfusion technique. Tributyrin  [60-01-5], tricaprylin  [538-23-8], and Et laurate  [106-33-2] were used as lipid vehicles able to increase the absorption of these drugs. For this series of xanthine derivatives, absorption was higher from oil solutions than from Sorensen buffer when the drug partition coefficient was <1. Although the affinity of the drugs for the vehicle was related to the absorption profiles, this could not explain all the absorption results. There was strong evidence that the nature of the oil plays concomitantly an important role. This was particularly the case for Et laurate, which highly increased the intestinal absorption of theophylline  [58-55-9]. Measurements of the appearance of this drug in the rat blood confirmed the favorable effect of this vehicle. Theophylline was further perfused as a suspension in Et laurate in order to test the effects of a higher drug-to-oil ratio. In this case, absorption from the oil suspension was of the same extent as an aqueous solution of identical concentration This seems to indicate that Et laurate may also affect the solubilization of the solid drug. When you point to this article, it is believed that you are also very interested in this compound(1028-33-7)SDS of cas: 1028-33-7 and due to space limitations, I can only present the most important information.

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Tetrahydrofuran – Wikipedia,
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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 Improving the Selectivity of PACE4 Inhibitors through Modifications of the P1 Residue, published in 2018-12-27, which mentions a compound: 26218-78-0, mainly applied to PACE4 inhibitors sequence prostate neoplasm antitumor, Quality Control of Methyl 6-bromonicotinate.

Paired basic amino acid cleaving enzyme 4 (PACE4), a serine endoprotease of the proprotein convertases family, has been recognized as a promising target for prostate cancer. We previously reported a selective and potent peptide-based inhibitor for PACE4, named the multi-Leu peptide (Ac-LLLLRVKR-NH2 sequence), which was then modified into a more potent and stable compound named C23 with the following structure: Ac-DLeu-LLLRVK-Amba (Amba: 4-amidinobenzylamide). Despite improvements in both in vitro and in vivo profiles of C23, its selectivity for PACE4 over furin was significantly reduced. We examined other Arg-mimetics instead of Amba to regain the lost selectivity. Our results indicated that the replacement of Amba with 5-(aminomethyl)picolinimidamide increased affinity for PACE4 and restored selectivity. Our results also provide a better insight on how structural differences between S1 pockets of PACE4 and furin could be employed in the rational design of selective inhibitors.

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Tetrahydrofuran – Wikipedia,
Tetrahydrofuran | (CH2)3CH2O – PubChem

HPLC of Formula: 313342-24-4. The fused heterocycle is formed by combining a benzene ring with a single heterocycle, or two or more single heterocycles. Compound: N-((1S,2S)-2-Amino-1,2-diphenylethyl)-2,3,4,5,6-pentafluorobenzenesulfonamide, is researched, Molecular C20H15F5N2O2S, CAS is 313342-24-4, about Reaction Development and Mechanistic Study of a Ruthenium Catalyzed Intramolecular Asymmetric Reductive Amination en Route to the Dual Orexin Inhibitor Suvorexant (MK-4305). Author is Strotman, Neil A.; Baxter, Carl A.; Brands, Karel M. J.; Cleator, Ed; Krska, Shane W.; Reamer, Robert A.; Wallace, Debra J.; Wright, Timothy J..

The 1st example of an intramol. asym. reductive amination of a dialkyl ketone with an aliphatic amine was developed for the synthesis of Suvorexant (MK-4305), a potent dual Orexin antagonist under development for the treatment of sleep disorders. This challenging transformation is mediated by a novel Ru-based transfer hydrogenation catalyst that provides the desired diazepane ring in 97% yield and 94.5% ee. Mechanistic studies revealed that CO2, produced as a necessary byproduct of this transfer hydrogenation reaction, has pronounced effects on the efficiency of the Ru catalyst, the form of the amine product, and the kinetics of the transformation. A simple kinetic model explains how product inhibition by CO2 leads to overall 1st-order kinetics, but yields an apparent zero-order dependence on initial substrate concentration The deleterious effects of CO2 on reaction rates and product isolation can be overcome by purging CO2 from the system. The transfer hydrogenation of acetophenone with this same catalyst system was examined The rate of ketone hydrogenation was greatly accelerated by purging of CO2 or trapping with nucleophilic secondary amines.

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Tetrahydrofuran – Wikipedia,
Tetrahydrofuran | (CH2)3CH2O – PubChem

Category: tetrahydrofurans. The mechanism of aromatic electrophilic substitution of aromatic heterocycles is consistent with that of benzene. Compound: 2-Amino-5-chlorobenzaldehyde, is researched, Molecular C7H6ClNO, CAS is 20028-53-9, about Iodine-Catalyzed Annulations of 2-Amino Carbonyls for Diverse 1-Azaxanthones, Quinolines, and Naphthyridines. Author is Cai, Hongyun; Datta Khanal, Hari; Rok Lee, Yong.

An efficient and facile iodine-catalyzed reaction of 2-amino carbonyls with β-enamino esters or β-enaminones afforded 1-azaxanthones, quinolines and naphthyridines in good to excellent yields. This novel catalytic [4+2] annulation reaction proceeded through a cascade I2-activation, Michael addition, intramol. aldol reaction and aromatization.

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Tetrahydrofuran – Wikipedia,
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Quality Control of 8-Bromoguanine. 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: 8-Bromoguanine, is researched, Molecular C5H4BrN5O, CAS is 3066-84-0, about Electronic spectra of 8-bromoguanine and 8-bromoadenine. Author is Pandey, K. S.; Mishra, P. C..

Absorption and fluorescence spectra of oxygenated and UV-irradiated aqueous solutions of 8-bromoguanine (BG) and 8-bromoadenine (BA), and pH effect on the spectra were studied. Each of BG and BA seem to have an asym. double-well ground state, like the parent mols. guanine and adenine. A qual. comparison of BG and BA with guanine and adenine in these respects was made. BG is much less affected by oxygenation and UV irradiation than is guanine. BA is affected by such treatments, but to a smaller extent than adenine. The mechanism of interaction of oxygen with the mols. under UV irradiation and the possible significance of the results is discussed.

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Tetrahydrofuran – Wikipedia,
Tetrahydrofuran | (CH2)3CH2O – PubChem