Month: April 2022

The reaction of an aromatic heterocycle with a proton is called a protonation. One of articles about this theory is 《Silylium-Ion Regeneration by Protodesilylation Enables Friedel-Crafts Alkylation with Less Isomerization and No Defunctionalization》. Authors are He, Tao; Klare, Hendrik F. T.; Oestreich, Martin.The article about the compound:1-(Bromomethyl)-4-iodobenzenecas:16004-15-2,SMILESS:IC1=CC=C(CBr)C=C1).Recommanded Product: 16004-15-2. Through the article, more information about this compound (cas:16004-15-2) is conveyed.

An improved protocol for the Friedel-Crafts alkylation of benzene as well as its methylated and halogenated derivatives with alkyl and benzyl bromides is reported. The reaction is promoted by a counteranion-stabilized silylium ion in the presence of stoichiometric amounts of a simple phenyl-substituted tetraorganosilane. This additive functions as a proton scavenger, regenerating the catalytically active silylium ion through protonation (protodesilylation) by the Wheland intermediate. It is a productive “”proton-into-silylium ion”” generator. The higher proton affinity of silylated compared with alkylated arenes results in fast proton transfer from the Bronsted acidic Wheland intermediate to the ipso position of that phenylsilane, thereby preventing otherwise competing defunctionalization and isomerization at the stage of the Wheland intermediate. The additive was also found to be crucial for turnover in the alkylation with primary alkyl bromides and for the suppression of transbenzylation in the benzylation with more reactive benzyl bromides.

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Reference:
Piperazine – Wikipedia,
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Zhang, Ya-Wen; Shen, Zong-Xuan; Qin, Hong-Bing; Li, Yong-Hua; Yu, Kai-Bei published an article about the compound: (S)-1-(Dimethylamino)propan-2-ol( cas:53636-17-2,SMILESS:C[C@H](O)CN(C)C ).Application of 53636-17-2. 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:53636-17-2) through the article.

Some α-(dialkylamino) ketones and β-(dialkyl amino) ketones were reduced stereoselectively by 2 mol of borane-tetrahydrofuran in the presence of 10 mol% of an in situ-formed chiral oxazaborolidine, followed by diluted hydrochloric acid. The catalysts in this study included (3aR)-tetrahydro-1-methyl-3,3-diphenyl-1H,3H-pyrrolo[1,2-c][1,3,2]oxazaborole, (3aS)-tetrahydro-1-methyl-3,3-diphenyl-1H,3H-pyrrolo[1,2-c][1,3,2]oxazaborole and (4R,5S)-2-methyl-4,5-diphenyl-1,3,2-oxazaborolidine. The resulting amino alc.-borane complexes were treated with hydrogen chloride-glycol-methanol to give the optically active amino alc. with the ee up to 99%. For example, the reduction of 3-(4-morpholinyl)-1-phenyl-1-propanone gave (+)-(αR)-α-phenyl-4-morpholinepropanol in 87.3% yield. The intermediate α-phenyl-4-morpholinepropanol-borane complex was characterized by x-ray crystallog.

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Reference:
Piperazine – Wikipedia,
Piperazines – an overview | ScienceDirect Topics

The preparation of ester heterocycles mostly uses heteroatoms as nucleophilic sites, which are achieved by intramolecular substitution or addition reactions. Compound: (S)-Methyl 3-hydroxybutanoate( cas:53562-86-0 ) is researched.SDS of cas: 53562-86-0.Raval, R.; Baddeley, C. J.; Haq, S.; Louafi, S.; Murray, P.; Muryn, C.; Lorenzo, M. Ortega; Williams, J. published the article 《Complexities and dynamics of the enantioselective active site in heterogeneous catalysis》 about this compound( cas:53562-86-0 ) in Studies in Surface Science and Catalysis. Keywords: copper catalyst surface modified chiral mol activity; hydrogenation ketoester enantioselective site catalyst mechanism; methylacetoacetate hydrogenation stereocontrol chiral catalyst site. Let’s learn more about this compound (cas:53562-86-0).

Stereocontrol mechanisms in chirally modified metals in heterogeneous catalysis for enantioselective reactions were studied. Effective systems were produced by first modifying a metal surface with chiral mols. and, subsequently, conducting the enantioselective reaction on the modified surface. The asym. hydrogenation of β-ketoesters (methylacetoacetate) over R,R-tartaric acid and S-alanine modified Cu(110) surfaces was used as model. The products are S and R-methyl-3-hydroxybutyrates. Surface spectroscopy methods were used to characterize modified surfaces created under ultra-clean and controlled environments; the adsorbed modifiers, R,R-tartaric acid and S-alanine, display rich and complex phase diagrams in which the chem. nature and 2-dimensional organization of the chiral units varies considerably as a function of surface coverage and temperature The models suggested for stereocontrol involving one-to-one interaction between the adsorbed chiral modifier and the reactant (substrate) are, perhaps, too simplistic and careful account needs to be taken of the complexities and dynamic interplay between different modifier phases at a surface to fully understand the nature and scope of stereocontrol.

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Piperazine – Wikipedia,
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The three-dimensional configuration of the ester heterocycle is basically the same as that of the carbocycle. Compound: 2-Bromopriopionaldehydediethylacetal(SMILESS: CC(Br)C(OCC)OCC,cas:3400-55-3) is researched.Recommanded Product: (1S)-(-)-Camphanic acid. The article 《Enolate additions to a chiral 3-hydroxypropionate 2,3-dication equivalent. Enantioselective synthesis of β,δ-dihydroxy esters》 in relation to this compound, is published in Journal of Organic Chemistry. Let’s take a look at the latest research on this compound (cas:3400-55-3).

The use of optically active dicarbonyl cyclopentadienyliron(vinyl ether) BF4 salts, (e.g. (5R)-(dicarbonyl-η-cyclopentadienyliron)-5,6-dihydro-5-methyl-1,3-dioxin tetrafluoroborate), as enantioselective 3-hydroxypropionate 2,3-dication equivalent is outlined. They are readily available by exchange etherification of the dimethoxyethylene analog, and these were transformed to enantiomeric dicarbonyl (η-cyclopentadienyliron)(η2-1-methoxypropene) BF4 5 and ent-5. Complex 5 was converted to the corresponding p-methoxybenzyloxy vinyl ether complex by exchange etherification. Condensation of this salt with a number of terminal and nonterminal enolates yields adducts, which are then transformed by redox-promoted alkoxycarbonylation, followed by alc. deprotection, to optically active 2-methyl-3-hydroxy-5 keto esters. 1,3-Reduction of these ketols can be effected to give either syn- or anti-1,3-diols and thence their related pentanolides (e.g. (2R*,3S*,4R*,5S*)-5-ethyl-3-hydroxy-2,4-dimethyl-5-pentanolide).

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Piperazine – Wikipedia,
Piperazines – an overview | ScienceDirect Topics

Most of the compounds have physiologically active properties, and their biological properties are often attributed to the heteroatoms contained in their molecules, and most of these heteroatoms also appear in cyclic structures. A Journal, Journal of Organometallic Chemistry called Synthesis of a tris(pyrazolyl)borate-stabilized molybdenum alkylidene and its hydrolysis products. Crystal structures of TpMo(CH2C(Me)2Ph)(NAr)(O) and [TpMo(NAr)(O)]2O, Author is Vaughan, William M.; Abboud, Khalil A.; Boncella, James M., which mentions a compound: 18583-60-3, SMILESS is [BH-](N1N=CC=C1)(N2N=CC=C2)N3N=CC=C3.[K+], Molecular C9H10BKN6, Name: Potassiumtris(1-pyrazolyl)borohydride.

The synthesis of a tris(pyrazolyl)borate-stabilized molybdenum(VI) imido alkylidene complex, TpMo(CHC(Me)2Ph)(NAr)(OTf) (1) [Ar = 2,6-i-Pr2-C6H3, Ph = C6H5, OTf = OSO2CF3], has been achieved by addition of potassium hydridotris(1-pyrazolyl)borate (KTp) to Mo(CHC(CH3)2Ph)(NAr)(OTf)2(DME). Stirring compound 1 over alumina in the presence of H2O gave TpMo(CH2C(Me)2Ph)(NAr)(O) (2). Alternatively, compound 1 was converted to 2 by the addition of CsOH·H2O in THF. A single crystal of [TpMo(NAr)(O)]2O (4) was isolated from a solution of 2. Compounds 2 and 4 have been characterized by x-ray crystallog. and the bonding considerations about the molybdenum atoms are discussed.

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Reference:
Piperazine – Wikipedia,
Piperazines – an overview | ScienceDirect Topics

The preparation of ester heterocycles mostly uses heteroatoms as nucleophilic sites, which are achieved by intramolecular substitution or addition reactions. Compound: (S)-Methyl 3-hydroxybutanoate( cas:53562-86-0 ) is researched.Safety of (S)-Methyl 3-hydroxybutanoate.Ni, Hongliang; Yao, Shanjing published the article 《Biosynthesis of optically active methyl β-hydroxybutanoate by yeast cells》 about this compound( cas:53562-86-0 ) in Huaxue Fanying Gongcheng Yu Gongyi. Keywords: acetoacetate stereoselective reduction hydroxybutyrate yeast fermentation. Let’s learn more about this compound (cas:53562-86-0).

The Me β-hydroxybutanoate (MHB) with optically activity was synthesized by Me acetoacetate (MAA) over different yeasts in aqueous phase. Effects of reaction time, yeast concentration, glucose concentration, buffer pH, reaction temperature and substrate concentration on the yield and the stereoselectivity of (S)-MHB were investigated. The results showed that bakers’ yeast was effective catalyst. The optimal conditions were reaction time 4 h, bakers’ yeast 50 g/L, glucose 0.6 M, substrate MAA 0.05 M, pH 7, 35°. Me β-hydroxybutanoate yield and enantiomeric excess were 57% and 92%, resp.

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Reference:
Piperazine – Wikipedia,
Piperazines – an overview | ScienceDirect Topics

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.Zhang, Jingyu; Chen, Shiya; Chen, Fangfang; Xu, Wensheng; Deng, Guo-Jun; Gong, Hang researched the compound: 5-Fluoroindoline( cas:2343-22-8 ).HPLC of Formula: 2343-22-8.They published the article 《Dehydrogenation of Nitrogen Heterocycles Using Graphene Oxide as a Versatile Metal-Free Catalyst under Air》 about this compound( cas:2343-22-8 ) in Advanced Synthesis & Catalysis. Keywords: graphene oxide nitrogen heterocycle dehydrogenation catalyst green chem. We’ll tell you more about this compound (cas:2343-22-8).

Graphene oxide (GO) has been developed as an inexpensive, environmental friendly, metal-free carbocatalyst for the dehydrogenation of nitrogen heterocycles. Valuable compounds, such as quinoline, 3,4-dihydroisoquinoline, quinazoline, and indole derivatives, have been successfully used as substrates. The investigation of various oxygen-containing mols. with different conjugated systems indicated that both the oxygen-containing groups and large π-conjugated system in GO sheets are essential for this reaction.

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Piperazine – Wikipedia,
Piperazines – an overview | ScienceDirect Topics

The preparation of ester heterocycles mostly uses heteroatoms as nucleophilic sites, which are achieved by intramolecular substitution or addition reactions. Compound: (S)-Methyl 3-hydroxybutanoate( cas:53562-86-0 ) is researched.Formula: C5H10O3.Kobayashi, Yuichi; Kumar, G. Biju; Kurachi, Tomoaki; Acharya, Hukum P.; Yamazaki, Takashi; Kitazume, Tomoya published the article 《Furan Ring Oxidation Strategy for the Synthesis of Macrosphelides A and B》 about this compound( cas:53562-86-0 ) in Journal of Organic Chemistry. Keywords: furan ring oxidation macrosphelide A B synthesis. Let’s learn more about this compound (cas:53562-86-0).

By using the convenient protocol for conversion of 2-substituted furans into 4-oxo-2-alkenoic acids ((i) NBS, (ii) NaClO2), macrosphelide B (I, R = H) was synthesized from furyl alc. II (>98% ee) and (S)-Me3CSiMe2OCHMeCH2CO2H (99% ee). Key steps include condensation of (2E,5S)-5-(4-methoxybenzyloxy)-4-oxo-2-hexenoic acid with the furylmethyl ester III and intramol. cyclization of the adduct IV to I (R = MeOCH2). Transformation of I (R = MeOCH2) to macrosphelide A was then investigated. Although the chelation-controlled reduction of I (R = MeOCH2) should afford the desired anti alc., Zn(BH4)2 at <-90 °C gave a 2∼1:1 mixture of anti/syn alcs. On the contrary, reduction with NaBH4 in MeOH at -15 °C produced the syn isomer with >10:1 diastereoselectivity. Mitsunobu inversion of the resulting C(14)-hydroxyl group and deprotection of the MOM group with TFA afforded macrosphelide A. Similarly, reduction of I (R = H) with NaBH4 afforded the C(14)-epimer of macrosphelide A stereoselectively. The observed stereoselectivity in the reductions of I could be explained on the basis of computer-assisted calculation, which showed presence of the low-energy conformers responsible for the stereoselective reduction In addition, conversion of I (R = H) to macrosphelide A was established, for the first time.

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Reference:
Piperazine – Wikipedia,
Piperazines – an overview | ScienceDirect Topics

Name: 2,3-Dichloro-5-iodopyridine. The mechanism of aromatic electrophilic substitution of aromatic heterocycles is consistent with that of benzene. Compound: 2,3-Dichloro-5-iodopyridine, is researched, Molecular C5H2Cl2IN, CAS is 97966-01-3, about Synthesis and Structure-Activity Relationships of 3,8-Diazabicyclo[4.2.0]octane Ligands, Potent Nicotinic Acetylcholine Receptor Agonists. Author is Frost, Jennifer M.; Bunnelle, William H.; Tietje, Karin R.; Anderson, David J.; Rueter, Lynne E.; Curzon, Peter; Surowy, Carol S.; Ji, Jianquo; Daanen, Jerome F.; Kohlhaas, Kathy L.; Buckley, Michael J.; Henry, Rodger F.; Dyhring, Tino; Ahring, Philip K.; Meyer, Michael D..

A series of potent neuronal nicotinic acetylcholine receptor (nAChR) ligands based on a 3,8-diazabicyclo[4.2.0]octane core have been synthesized and evaluated for affinity and agonist efficacy at the human high affinity nicotine recognition site (hα4β2) and in a rat model of persistent nociceptive pain (formalin model). Numerous analogs in this series exhibit picomolar affinity in radioligand binding assays and nanomolar agonist potency in functional assays, placing them among the most potent nAChR ligands known for the hα4β2 receptor. The 3,8-diazabicyclo[4.2.0]octanes (1R,6S)-I [R = H, Cl, Me, R1 = Cl; R = Br, Cn, R1 = Br] and (1S,6R)-I [R = H, R1 = Cl] exhibit equivalent or greater affinity for the hα4β2 receptor relative to epibatidine, and like epibatidine, many exhibit robust analgesic efficacy in the rat formalin model of persistent pain.

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Reference:
Piperazine – Wikipedia,
Piperazines – an overview | ScienceDirect Topics

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.Banno, Taisuke; Kawada, Kazuo; Matsumura, Shuichi researched the compound: (S)-1-(Dimethylamino)propan-2-ol( cas:53636-17-2 ).Safety of (S)-1-(Dimethylamino)propan-2-ol.They published the article 《Chemo-enzymatic synthesis and properties of novel optically active cationics containing carbonate linkages》 about this compound( cas:53636-17-2 ) in Journal of Oleo Science. Keywords: carbonate type cationic synthesis enzyme. We’ll tell you more about this compound (cas:53636-17-2).

Novel optically active carbonate-type cationics were designed and synthesized via a green method. A series of n-alkyl N,N-dimethylaminoalkyl carbonates was prepared via a two-step successive carbonate exchange reaction of di-Ph carbonate with 1-alkanol followed by the reaction of the optically active or racemic amino alc. in the presence of triethylamine. The quaternarization of the N,N-dimethylamino group was carried out using Me iodide. Furthermore, optically active cationics were prepared by the lipase-catalyzed enantioselective hydrolysis of the racemic cationics. Carbonate-type cationics having an isopropylene linkage showed high hydrolytic stability. They exhibited surfactant properties similar to those of the corresponding racemic cationics. Although no significant differences in the antimicrobial activities were observed owing to the stereochem. of the cationics, the biodegradability was strongly influenced by the stereochem. Some optically active cationics were rapidly biodegraded by activated sludge.

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Reference:
Piperazine – Wikipedia,
Piperazines – an overview | ScienceDirect Topics