- Multiple-photon ? chemistry in the laser-jet: Photochemistry of the 4-biphenylmethyl radical
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In laser-jet (LJ) photolysis (high intensity) of the ether 4-(4-benzoylphenoxymethyl)biphenyl 1 a two-photon process is observed in CCl4 to yield 4-(chloromethyl)biphenyl 5 as product (3%), while the one-photon product is 4-biphenylaldehyde 7 (100% in conventional photolysis versus 97% in laser-jet photolysis). In ethanol, the results suggest a three-proton reaction in which 4-(ethoxymethyl)biphenyl 6 is produced in appreciable amounts (18%) in addition to the one-photon product 1,2-bis(4-biphenyl)ethane 4, the latter as the major product (82%). It is proposed that under high-intensity LJ photolysis conditions the electronically-excited 4-biphenylmethyl radical 2* is photoionized to the 4-biphenylmethyl cation 2+ and that the latter is trapped by ethanol to give the 4-biphenylmethyl ether 6.
- Adam, Waldemar,Schneider, Katrin
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Read Online
- Palladium-anchored multidentate SBA-15/di-urea nanoreactor: A highly active catalyst for Suzuki coupling reaction
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Modification of mesoporous silica was carried out by reaction of SBA-15 with di-urea-based ligand. Next, with the help of this ligand, palladium ions were anchored within the multidentate SBA-15/di-urea pore channels with high dispersion. The SBA-15/di-urea/Pd catalyst was characterized using various techniques. Theoretical calculations indicated that each palladium ion was strongly interacted with one nitrogen and two oxygen atoms from the multidentate di-urea ligand located in SBA-15 channels and these interactions remained during the catalytic cycle. These results are in good agreement with those of hot filtration test: the palladium ions have very high stability against leaching from the SBA-15/di-urea support. The catalytic performance of SBA-15/di-urea/Pd nanostructure was examined for the Suzuki coupling reaction of phenylboronic acid and electronically diverse aryl halides under mild conditions with a minimal amount of Pd (0.26?mol%). Compared to previous reports, this protocol afforded some advantages such as short reaction times, high yields of products, catalyst stability without leaching, easy catalyst recovery and preservation of catalytic activity for at least six successive runs.
- Rohani, Sahar,Mohammadi Ziarani, Ghodsi,Badiei, Alireza,Ziarati, Abolfazl,Jafari, Maryam,Shayesteh, Alireza
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Read Online
- Mechanism of solvolysis of substituted benzyl chlorides in aqueous ethanol
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The mechanism of solvolyses of activated ortho-, meta- and para-substituted benzyl chlorides in aqueous ethanol has been studied by using the Hammett-Brown and Yukawa-Tsuno treatments as well as by correlating logarithms of solvolysis rate constants with relative stabilities of corresponding benzyl carbocations in water calculated at the IEFPCM-M06–2X/6-311+G(3df,3pd) level of theory. Benzyl chlorides containing strong conjugative electron-donors in the para-position solvolyze by the SN1 mechanism, whereas other activated benzyl chlorides solvolyze by the SN2 mechanism via loose transition states.
- Denegri, Bernard,Mati?, Mirela,Va?ko, Monika
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supporting information
(2021/11/22)
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- Palladium-catalyzed carbonylative cyclization of benzyl chlorides with anthranils for the synthesis of 3-arylquinolin-2(1: H)-ones
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An efficient carbonylative procedure for the synthesis of 3-arylquinoin-2(1H)-ones has been established. Through a palladium-catalyzed aminocarbonylation of benzyl chlorides with anthranils, a variety of 3-arylquinoin-2(1H)-one products were obtained in moderate to excellent yields with good functional group tolerance. This journal is
- Liu, Jian-Li,Xu, Ren-Rui,Wang, Wei,Qi, Xinxin,Wu, Xiao-Feng
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supporting information
p. 3584 - 3588
(2021/05/04)
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- Synthesis and evaluation of tetrahydroisoquinoline derivatives against Trypanosoma brucei rhodesiense
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Human African Trypanosomiasis (HAT) is a neglected tropical disease caused by the parasitic protozoan Trypanosoma brucei (T. b.), and affects communities in sub-Saharan Africa. Previously, analogues of a tetrahydroisoquinoline scaffold were reported as having in vitro activity (IC50 = 0.25–70.5 μM) against T. b. rhodesiense. In this study the synthesis and antitrypanosomal activity of 80 compounds based around a core tetrahydroisoquinoline scaffold are reported. A detailed structure activity relationship was revealed, and five derivatives (two of which have been previously reported) with inhibition of T. b. rhodesiense growth in the sub-micromolar range were identified. Four of these (3c, 12b, 17b and 26a) were also found to have good selectivity over mammalian cells (SI > 50). Calculated logD values and preliminary ADME studies predict that these compounds are likely to have good absorption and metabolic stability, with the ability to passively permeate the blood brain barrier. This makes them excellent leads for a blood-brain barrier permeable antitrypanosomal scaffold.
- Cullen, Danica R.,Gallagher, Ashlee,Duncan, Caitlin L.,Pengon, Jutharat,Rattanajak, Roonglawan,Chaplin, Jason,Gunosewoyo, Hendra,Kamchonwongpaisan, Sumalee,Payne, Alan,Mocerino, Mauro
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- Visible Light-Catalyzed Benzylic C-H Bond Chlorination by a Combination of Organic Dye (Acr+-Mes) and N-Chlorosuccinimide
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By combining "N-chlorosuccinimide (NCS)"as the safe chlorine source with "Acr+-Mes"as the photocatalyst, we successfully achieved benzylic C-H bond chlorination under visible light irradiation. Furthermore, benzylic chlorides could be converted to benzylic ethers smoothly in a one-pot manner by adding sodium methoxide. This mild and scalable chlorination method worked effectively for diverse toluene derivatives, especially for electron-deficient substrates. Careful mechanistic studies supported that NCS provided a hydrogen abstractor "N-centered succinimidyl radical,"which was responsible for the cleavage of the benzylic C-H bond, relying on the reducing ability of Acr?-Mes.
- Xiang, Ming,Zhou, Chao,Yang, Xiu-Long,Chen, Bin,Tung, Chen-Ho,Wu, Li-Zhu
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p. 9080 - 9087
(2020/08/14)
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- Nickel-Catalyzed Asymmetric Reductive Arylbenzylation of Unactivated Alkenes
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Herein, we report a nickel-catalyzed asymmetric two-component reductive dicarbofunctionalization of aryl iodide-tethered unactivated alkenes using benzyl chlorides as the challenging coupling partner. This arylbenzylation reaction enables the efficient synthesis of diverse benzene-fused cyclic compounds bearing a quaternary stereocenter with a high tolerance of sensitive functionalities in highly enantioselective manner. The preliminary mechanistic investigations suggest a radical chain reaction mechanism.
- Jin, Youxiang,Yang, Haobo,Wang, Chuan
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supporting information
p. 2724 - 2729
(2020/04/02)
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- Biphenyl acetic acid and preparation method thereof
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The invention discloses biphenyl acetic acid and a preparation method thereof. The preparation method comprises the following steps: dissolving bromobenzene into dimethylformamide, and performing reaction under the action of palladium powder to obtain biphenyl; dissolving biphenyl in cyclohexane, and performing chloromethylation reaction on biphenyl in a hydrochloric acid solution and a saturatedformaldehyde aqueous solution to obtain an intermediate 1; dissolving sodium cyanide in deionized water, and performing cyanidation reaction on the intermediate 1 and a sodium cyanide aqueous solutionunder the action of a catalyst n-butylammonium bromide to obtain an intermediate 2; and further hydrolyzing the intermediate 2 under the condition of an alkaline aqueous solution, and performing acidifying under the action of hydrochloric acid to obtain biphenyl acetic acid. The yield of the biphenyl acetic acid prepared by the aid of the method is higher than that of the biphenyl acetic acid prepared by the aid of traditional processes, reactants are low in price, the preparation cost of the biphenyl acetic acid can be greatly reduced, and the method is favorable for market popularization.
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- Operando Spectroscopic and Kinetic Characterization of Aerobic Allylic C-H Acetoxylation Catalyzed by Pd(OAc)2/4,5-Diazafluoren-9-one
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Allylic C-H acetoxylations are among the most widely studied palladium(II)-catalyzed C-H oxidation reactions. While the principal reaction steps are well established, key features of the catalytic mechanisms are poorly characterized, including the identity of the turnover-limiting step and the catalyst resting state. Here, we report a mechanistic study of aerobic allylic acetoxylation of allylbenzene with a catalyst system composed of Pd(OAc)2 and 4,5-diazafluoren-9-one (DAF). The DAF ligand is unique in its ability to support aerobic catalytic turnover, even in the absence of benzoquinone or other co-catalysts. Herein, we describe operando spectroscopic analysis of the catalytic reaction using X-ray absorption and NMR spectroscopic methods that allow direct observation of the formation and decay of a palladium(I) species during the reaction. Kinetic studies reveal the presence of two distinct kinetic phases: (1) a burst phase, involving rapid formation of the allylic acetoxylation product and formation of the dimeric PdI complex [PdI(DAF)(OAc)]2, followed by (2) a post-burst phase that coincides with evolution of the catalyst resting state from the PdI dimer into a π-allyl-PdII species. The data provide unprecedented insights into the role of ancillary ligands in supporting catalytic turnover with O2 as the stoichiometric oxidant and establish an important foundation for the development of improved catalysts for allylic oxidation reactions.
- Jaworski, Jonathan N.,Kozack, Caitlin V.,Tereniak, Stephen J.,Knapp, Spring Melody M.,Landis, Clark R.,Miller, Jeffrey T.,Stahl, Shannon S.
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p. 10462 - 10474
(2019/07/09)
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- α-Diimine-Niobium Complex-Catalyzed Deoxychlorination of Benzyl Ethers with Silicon Tetrachloride
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α-Diimine niobium complexes serve as catalysts for deoxygenation of benzyl ethers by silicon tetrachloride (SiCl4) to cleanly give two equivalents of the corresponding benzyl chlorides, where SiCl4 has the dual function of oxygen scavenger and chloride source with the formation of a silyl ether or silica as the only byproduct. The reaction mechanism has two successive trans-etherification steps that are mediated by the niobium catalyst, first forming one equivalent of benzyl chloride along with the corresponding silyl ether intermediate that undergoes the same reaction pathway to give the second equivalent of benzyl chloride and silyl ether.
- Parker, Bernard F.,Hosoya, Hiromu,Arnold, John,Tsurugi, Hayato,Mashima, Kazushi
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supporting information
p. 12825 - 12831
(2019/10/19)
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- An efficient and convenient chloromethylation of some aromatic compounds catalyzed by zinc iodide
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Treatment of a series of aromatic hydrocarbons and O-carbethoxy phenol substrates with a mixture of chlorosulfonic acid and dimethoxymethane in CH2Cl2 catalyzed by zinc iodide affords the corresponding chloromethyl derivatives in good to excellent yields.
- Tang, Jian,Liu, Hongtao,Zhou, Jing,Zhang, Xingxian
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- A practical and convenient Blanc-type chloromethylation catalyzed by zinc chloride under solvent-free conditions
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Chloromethylation of various aromatic hydrocarbons and substituted phenolic derivatives with dimethoxymethane and chlorosulfonic acid was carried out in the presence of 10 mol% of ZnCl2 in a mild and efficient manner under solvent-free conditions. In addition, 2,6-dimethyltyrosine was synthesized in high yield via this protocol.
- Tang, Jian,Liu, Hongtao,He, Kailun,Zhang, Xingxian
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p. 925 - 932
(2019/03/17)
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- Late-Stage Functionalization of Arylacetic Acids by Photoredox-Catalyzed Decarboxylative Carbon–Heteroatom Bond Formation
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The rapid transformation of pharmaceuticals and agrochemicals enables access to unexplored chemical space and thus has accelerated the discovery of novel bioactive molecules. Because arylacetic acids are regarded as key structures in bioactive compounds, new transformations of these structures could contribute to drug/agrochemical discovery and chemical biology. This work reports carbon–nitrogen and carbon–oxygen bond formation through the photoredox-catalyzed decarboxylation of arylacetic acids. The reaction shows good functional group compatibility without pre-activation of the nitrogen- or oxygen-based coupling partners. Under similar reaction conditions, carbon–chlorine bond formation was also feasible. This efficient derivatization of arylacetic acids makes it possible to synthesize pharmaceutical analogues and bioconjugates of pharmaceuticals and natural products.
- Sakakibara, Yota,Ito, Eri,Fukushima, Tomohiro,Murakami, Kei,Itami, Kenichiro
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supporting information
p. 9254 - 9258
(2018/06/04)
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- Manganese-salen catalyzed oxidative benzylic chlorination
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Abstract: Metalloporphyrins are well-known to serve as the model for mimicking reactivities exhibited by cytochrome P450 hydroxylase. Recent developments on selective C–H halogenation using Mn-porphyrins provided the way for understanding the reactivity as well as mechanism of different halogenase enzymes. In this report, we demonstrated a method for benzylic C–H chlorination using easily prepared Mn(salen) complex as the catalyst, which shows a complementary reactivity of Mn-porphyrins. Here, NaOCl has been used as a chlorinating source as well as the oxidant. Efforts towards understanding the mechanism suggested the formation of the high-valent Mn(V)=O species which is believed to be the key intermediate to conduct this transformation. Graphical abstract: SYNOPSIS Mn(salen)-catalyzed selective benzylic chlorination protocol has been developed using aqueous NaOCl solution. Reactions proceeded efficiently at room temperature and displayed good functional group tolerance. The mechanistic investigation demonstrated that Mn (V) = O species is likely to be the key intermediate which is responsible to generate benzylic radical. EPR and ESI-MS studies confirmed the in situ formation of Mn(IV)-species.[Figure not available: see fulltext.].
- Sasmal, Sheuli,Rana, Sujoy,Lahiri, Goutam Kumar,Maiti, Debabrata
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- Halogenation through Deoxygenation of Alcohols and Aldehydes
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An efficient reagent system, Ph3P/XCH2CH2X (X = Cl, Br, or I), was very effective for the deoxygenative halogenation (including fluorination) of alcohols (including tertiary alcohols) and aldehydes. The easily available 1,2-dihaloethanes were used as key reagents and halogen sources. The use of (EtO)3P instead of Ph3P could also realize deoxy-halogenation, allowing for a convenient purification process, as the byproduct (EtO)3Pa?O could be removed by aqueous washing. The mild reaction conditions, wide substrate scope, and wide availability of 1,2-dihaloethanes make this protocol attractive for the synthesis of halogenated compounds.
- Chen, Jia,Lin, Jin-Hong,Xiao, Ji-Chang
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supporting information
p. 3061 - 3064
(2018/05/28)
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- Pd-catalyzed, highly selective C(sp2)-Br bond coupling reactions of o-(or m-, or p-) chloromethyl bromobenzene with arylboronic acids
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Highly selective C(sp2)–C(sp2) cross-coupling of dihalogenated hydrocarbons comprising C(sp2)–Br and C(sp3)–Cl bonds with arylboronic acids is reported. This highly selective coupling reaction of the C(sp2)–Br bond is successfully achieved using Pd(OAc)2 and PCy3·HBF4 as the palladium source and ligand, respectively. A series of chloromethyl-1,1′-biphenyl compounds are obtained in moderate-to-excellent yields. Moreover, this protocol can be extended to the one-pot dual arylation of 1-bromo-4-(chloromethyl)benzene with two arylboronic acids, leading to diverse unsymmetrical 4-benzyl-1,1′-biphenyl derivatives.
- Pei, Ming-ming,Liu, Ping,Liu, Yan,Lv, Xin-ming,Ma, Xiao-wei,Dai, Bin
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- 4 - Biphenyl methanol synthesis method
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The invention discloses a 4-biphenyl methanol synthetic method. The method comprises the steps that 1, biphenyl, paraformaldehyde, phosphoric acid, concentrated hydrochloric acid and a catalyst are mixed and heated to 100-120 DEG C, and are subjected to a reaction in a closed system for 2-48 h, cooled and layered into a water layer and an organic layer; 2, the water layer obtained in the step 1 is removed, water is added into the organic layer, heating reflux is performed for 8-48 h, cooling and filtering are performed, and a crude product is obtained; 3, an organic solvent is used for achieving recrystallization on the crude product obtained in the step 2, and 4-biphenyl methanol is obtained. The 4-biphenyl methanol synthetic method has the advantages of being capable of obtaining raw materials easily, low in cost, suitable for industrial production and the like.
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Paragraph 0050; 0054; 0057; 0060; 0063; 0066; 0069
(2018/04/03)
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- Ketone-catalyzed photochemical C(sp3)–H chlorination
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Photoexcited arylketones catalyze the direct chlorination of C(sp3)–H groups by N- chlorosuccinimide. Acetophenone is the most effective catalyst for functionalization of unactivated C–H groups while benzophenone provides better yields for benzylic C–H functionalization. Activation of both acetophenone and benzophenone can be achieved by irradiation with a household compact fluorescent lamp. This light-dependent reaction provides a better control of the reaction as compared to the traditional chlorination methods that proceed through a free radical chain propagation mechanism.
- Han, Lei,Xia, Ji-Bao,You, Lin,Chen, Chuo
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p. 3696 - 3701
(2017/06/13)
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- Discovery of phenylsulfonyl acetic acid derivatives with improved efficacy and safety as potent free fatty acid receptor 1 agonists for the treatment of type 2 diabetes
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The free fatty acid receptor 1 (FFA1) has emerged as an attractive anti-diabetic target that mediates glucose-stimulated insulin secretion. Several FFA1 agonists have been reported, but many of them possessed somewhat high lipophilicity and/or molecular weight. Herein, we describe the identification of sulfone-carboxylic acid moiety with the multiple advantages of reducing lipophilicity, cytotoxicity and β-oxidation associated with compound 2. Further structure-activity relationship study based on the previleged scaffolds led to the discovery of 2-{(4-[(2’-chloro-[1,1’-biphenyl]-3-yl)methoxy]phenyl)sulfonyl}acetic acid (compound 20), which showed a better balance than compound 2 in terms of physicochemical properties, cytotoxicity profiles and pharmacokinetic properties. Subsequent in vivo studies demonstrated that compound 20 robustly improves the glucose tolerance both in normal and type 2 diabetic models without the risk of hypoglycemia. Compared to the high risk of TAK-875 induced liver toxicity, there was no significant adverse effects such as hepatic and renal toxicity were observed in the chronic toxicity studies of compound 20 even at the higher dose.
- Li, Zheng,Liu, Chunxia,Xu, Xue,Qiu, Qianqian,Su, Xin,Dai, Yuxuan,Yang, Jianyong,Li, Huilan,Shi, Wei,Liao, Chen,Pan, Miaobo,Huang, Wenlong,Qian, Hai
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p. 458 - 479
(2017/07/10)
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- Oxygen Activated, Palladium Nanoparticle Catalyzed, Ultrafast Cross-Coupling of Organolithium Reagents
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The discovery of an ultrafast cross-coupling of alkyl- and aryllithium reagents with a range of aryl bromides is presented. The essential role of molecular oxygen to form the active palladium catalyst was established; palladium nanoparticles that are highly active in cross-coupling reactions with reaction times ranging from 5 s to 5 min are thus generated in situ. High selectivities were observed for a range of heterocycles and functional groups as well as for an expanded scope of organolithium reagents. The applicability of this method was showcased by the synthesis of the [11C]-labeled PET tracer celecoxib.
- Heijnen, Dorus,Tosi, Filippo,Vila, Carlos,Stuart, Marc C. A.,Elsinga, Philip H.,Szymanski, Wiktor,Feringa, Ben L.
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supporting information
p. 3354 - 3359
(2017/03/17)
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- Preparation method of ethyl 2-amino-3-biphenylpropionate derivative hydrochloride
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The invention belongs to the technical field of fine chemical engineering or drug intermediate preparation, and particularly relates to a preparation method of ethyl 2-amino-3-biphenylpropionate derivative hydrochloride. The method comprises the following steps: carrying out chloromethylation reaction on the raw material biphenyl derivative to obtain a 4-chloromethyl biphenyl derivative, and carrying out substitution reaction to obtain the target product ethyl 2-amino-3-biphenylpropionate derivative hydrochloride. Compared with the prior art, the method has the advantages of short reaction route, fewer material varieties, simpler operation, no demands for high temperature and high pressure, low energy consumption and low cost. The obtained target product has the advantages of high yield and high quality. Therefore, the preparation method is suitable for mass production, and has favorable application prospects.
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Paragraph 0027; 0028
(2017/07/21)
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- Preparation and purification methods of 4-biphenylacetic acid
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The invention relates to the field of production preparation of compounds, in particular to preparation and purification methods of 4-biphenylacetic acid. The preparation and purification methods comprise steps as follows: 1) biphenyl is subjected to a chloromethylation reaction to produce 4-phenyl benzyl chloride; 2) 4-phenyl benzyl chloride reacts with sodium cyanide to produce 4-biphenyl acetonitrile; 3) 4-biphenyl acetonitrile is hydrolyzed and a crude 4-bphenylacetic acid product is obtained; 4) the crude 4-bphenylacetic acid product and methanol are subjected to an esterification reaction to produce 4-biphenyl methyl acetate, 4-biphenyl methyl acetate is purified and hydrolyzed into 4-biohenylacetic acid, 4-bihenylacetic acid is refined, and a finished product is prepared.
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Paragraph 0063; 0065; 0072; 0079
(2017/04/03)
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- Inherent vs Apparent Chemoselectivity in the Kumada-Corriu Cross-Coupling Reaction
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The Kumada-Corriu reaction is a powerful tool for C-C bond formation, but is seldom utilized due to perceived chemoselectivity issues. Herein, we demonstrate that high-yielding couplings can occur in the presence of many electrophilic and heterocyclic functional groups. Our strategy is mechanically based, matching oxidative addition rates with the rate of syringe pump addition of the Grignard reagent. The mechanistic reason for the effectiveness of this strategy is uncovered by continuous-infusion ESI-MS studies.
- Hua, Xiye,Masson-Makdissi, Jeanne,Sullivan, Ryan J.,Newman, Stephen G.
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supporting information
p. 5312 - 5315
(2016/11/02)
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- Synthetic process of 4-biphenylmethanol
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The invention discloses a synthetic process of 4-biphenylmethanol, and belongs to the field of compound synthetic methods. The synthetic process comprises the following steps: 1) chloromethylation reaction: sealing and stirring biphenyl, paraformaldehyde, phosphoric acid and hydrochloric acid, heating to 80-130DEG C, reacting for 20h at the pressure of 0.08-0.4Mpa, carrying out cooling layering, and collecting an upper layer intermediate; 2) hydrolysis reaction: adding the intermediate, water and 150kg of DMF (Dimethyl Formamide) into a reaction still, carrying out sealing stirring, heating to 80-130DEG C, reacting for 20h at the pressure of 0.08-0.3Mpa, cooling for decompression, cooling for devitrification, and carrying out centrifugation to obtain a crude product; 3) refining process: adding the crude product, ethyl acetate and activated carbon into the reaction still, heating to 80DEG C at the normal pressure, stirring for 1 hour, carrying out hot filtration, cooling and centrifuging filtrate, and drying to obtain a finished product. The synthetic process has the advantages of abundant raw materials, low production cost, simple operation of whole synthetic process, reasonable step design, convenience in scale-up experiment and high safety.
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Paragraph 0022-0024
(2017/04/03)
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- Iron catalyzed halogenation of benzylic aldehydes and ketones
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A simple and efficient iron-catalyzed method for chlorination of aromatic carbonyl compounds is reported. By using 4-10 mol% Fe(iii) oxo acetate catalyst, prepared by solid state atmospheric oxidation of Fe(ii) acetate, in combination with triethylsilane and chlorotrimethylsilane, hydrosilylation of benzylic carbonyl compounds with subsequent chlorination is achieved within a few hours at room temperature. This new method is mild and rapid compared to the conventional two step approach involving reduction and chlorination reactions in separate stages. Development of synthetic methodology is also supplemented here by kinetic investigation of the reaction mechanism, which supports the tentative mechanisms suggested previously for similar reactions. This journal is
- Savela, Risto,W?rn?, Johan,Murzin, Dmitry Yu.,Leino, Reko
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p. 2406 - 2417
(2015/04/14)
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- Sulfite formation versus chlorination of benzyl alcohols with thionyl chloride
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Recently, we have reported the photolytic decay of a library of para-substituted dibenzylic sulfites in a Srinivasan-Griffin-Rayonet photochemical reactor. In an attempt to synthesize the complete library for that study we discovered that bis(p-methoxybenzyl) sulfite and bis(p-phenoxybenzyl) sulfite could not be formed and only their corresponding benzyl chlorides were synthesized. Thus, sulfite formation versus chlorination of a range of para-substituted benzyl alcohols with thionyl chloride was investigated. Sulfite formation was observed to be parabolically related to Swain and Lupton's Field ?-values while chloride formation was found to be linearly related to Swain and Lupton's Field ?-values.
- Rodriguez, Deana A.,Priefer, Ronny
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p. 3045 - 3048
(2014/05/20)
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- Cu-Catalyzed Suzuki-Miyaura reactions of primary and secondary benzyl halides with arylboronates
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A copper-catalyzed Suzuki-Miyaura coupling of benzyl halides with arylboronates is described. Varieties of primary benzyl halides as well as more challenging secondary benzyl halides with β hydrogens or steric hindrance could be successfully converted into the corresponding products. Thus it provides access to diarylmethanes, diarylethanes and triarylmethanes. This journal is the Partner Organisations 2014.
- Sun, Yan-Yan,Yi, Jun,Lu, Xi,Zhang, Zhen-Qi,Xiao, Bin,Fu, Yao
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supporting information
p. 11060 - 11062
(2014/09/30)
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- Silver-catalyzed decarboxylative chlorination of aliphatic carboxylic acids
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Decarboxylative halogenation of carboxylic acids, the Hunsdiecker reaction, is one of the fundamental functional group transformations in organic chemistry. As the initial method requires the preparations of strictly anhydrous silver carboxylates, several modifications have been developed to simplify the procedures. However, these methods suffer from the use of highly toxic reagents, harsh reaction conditions, or limited scope of application. In addition, none is catalytic for aliphatic carboxylic acids. In this Article, we report the first catalytic Hunsdiecker reaction of aliphatic carboxylic acids. Thus, with the catalysis of Ag(Phen)2OTf, the reactions of carboxylic acids with t-butyl hypochlorite afforded the corresponding chlorodecarboxylation products in high yields under mild conditions. This method is not only efficient and general, but also chemoselective. Moreover, it exhibits remarkable functional group compatibility, making it of more practical value in organic synthesis. The mechanism of single electron transfer followed by chlorine atom transfer is proposed for the catalytic chlorodecarboxylation.
- Wang, Zhentao,Zhu, Lin,Yin, Feng,Su, Zhongquan,Li, Zhaodong,Li, Chaozhong
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experimental part
p. 4258 - 4263
(2012/04/10)
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- An inexpensive and convenient procedure for chloromethylation of aromatic hydrocarbons by phase transfer catalysis in aqueous media
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Reaction of aromatic hydrocarbons catalyzed by a novel catalytic system consisting of zinc chloride, acetic acid, sulfuric acid and PEG-800 in aqueous media under PTC conditions results in chloromethylation in good to excellent yield.
- Hu, Yu Lin,Lu, Ming,Ge, Qiang,Wang, Peng Cheng,Zhang, Sheng Bin,Lu, Ting Ting
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experimental part
p. 97 - 102
(2010/08/05)
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- Studies on novel 2-imidazolidinones and tetrahydropyrimidin-2(1H)-ones as potential TACE inhibitors: Design, synthesis, molecular modeling, and preliminary biological evaluation
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Compounds belonging to the class of 2-imidazolidinones and tetrahydropyrimidin-2(1H)-ones were synthesized and evaluated for their TACE inhibitory activity. Most of the compounds showed very good TACE inhibitory activity. Docking study clearly indicates importance of the P1′ group of the inhibitor for the TACE inhibitory activity. This work proves that these two classes of molecules could be used as potential leads for the development of TACE inhibitors.
- DasGupta, Shirshendu,Murumkar, Prashant R.,Giridhar, Rajani,Yadav, Mange Ram
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experimental part
p. 3604 - 3617
(2009/09/30)
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- MODULATORS OF C3A RECEPTOR AND METHODS OF USE THEREOF
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Provided are compounds that are modulators of C3a receptor activity, compositions containing the compounds and methods of use of the compounds and compositions. In certain embodiments, the compounds are pyridones. In certain embodiments, provided are methods for treatment or amelioration of diseases associated with modulation of C3a receptor activity.
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Page/Page column 83
(2008/12/07)
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- C17,20-lyase inhibitors I. Structure-based de novo design and SAR study of C17,20-lyase inhibitors.
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Novel nonsteroidal C(17,20)-lyase inhibitors were synthesized using de novo design based on its substrate, 17 alpha-hydroxypregnenolone, and several compounds exhibited potent C(17,20)-lyase inhibition. However, in vivo activities were found to be short-lasting, and in order to improve the duration of action, a series of benzothiophene derivatives were evaluated. As a result, compounds 9h, (S)-9i, and 9k with nanomolar enzyme inhibition (IC(50)=4-9 nM) and 9e (IC(50)=27 nM) were identified to have powerful in vivo efficacy with extended duration of action. The key structural determinants for the in vivo efficacy were demonstrated to be the 5-fluoro group on the benzothiophene ring and the 4-imidazolyl moiety. Superimposition of 9k and 17 alpha-hydroxypregnenolone demonstrated their structural similarity and enabled rationalization of the pharmacological results. In addition, selected compounds were also identified to be potent inhibitors of human enzyme with IC(50) values of 20-30 nM.
- Matsunaga, Nobuyuki,Kaku, Tomohiro,Itoh, Fumio,Tanaka, Toshimasa,Hara, Takahito,Miki, Hiroshi,Iwasaki, Masahiko,Aono, Tetsuya,Yamaoka, Masuo,Kusaka, Masami,Tasaka, Akihiro
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p. 2251 - 2273
(2007/10/03)
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- A duality of mechanisms for the fragmentation of substituted benzyloxychlorocarbenes
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Substituted benzyloxychlorocarbenes (X-PhCH2OCCl) were generated photochemically at 25 °C in dichloroethane from appropriate diazirine precursors. Fragmentations of the carbenes produced were determined by laser flash photolysis. The data (X, kfrag in s-1) were: p-Me, 2.6 × 105; p-Ph, 8.3 × 104; H, 6.0 × 104; p-Cl, 5.2 × 104; m-Cl, 1.3 × 105; p-F3C, 2.1 × 106; p-O2N, 6.3 × 106. A Hammett correlation of log kfrag versus σ+ was parabolic. The curvature was taken to imply the gradual change of the fragmentation mechanism from predominantly heterolytic for X-PhCH2CCl with electron-donating X (with developing positive charge on the benzylic carbon in the transition state) to predominantly homolytic for carbenes with electron-withdrawing X. This idea was supported by computational studies. Copyright
- Moss, Robert A.,Ma, Yan,Sauers, Ronald R.
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p. 13968 - 13969
(2007/10/03)
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- Remarkable interaction effects of molecular packing on site- and stereoselectivity in photocycloaddition of 2-pyrones with maleimide in the solid state
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Solid-state photoirradiation of 1:1 complex crystals of 4-[ω-(2-furyl)alkyloxy]-6-methyl-2-pyrones 1b, 1c or 4-(ω-arylalkyloxy)-6-methyl-2-pyrones 1d-j with maleimide 2 gave [2+2]cycloadducts 3b-f, 3i, 3j with exclusive stereoselectivity. The high reaction selectivity was confirmed by X-ray structure analyses and MO method of the complex crystals, which were composed of two sets of a 1:1 complex between 1 and 2, arising from an CH-π interaction between 2 and the aromatic rings of 1, and/or π-π stacking between the aromatic rings in addition to four kinds of hydrogen bonding between the ground state 2-pyrone moieties and 2.
- Obata, Toru,Shimo, Tetsuro,Yasutake, Mikio,Shinmyozu, Teruo,Kawaminami, Masaru,Yoshida, Ryosuke,Somekawa, Kenichi
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p. 1531 - 1541
(2007/10/03)
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- Rearrangement of 1,3-Diradicals. Arylcyclopropane Photochemistry
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The photochemistry of a series of aryl-substituted cyclopropanes was investigated as part of our continuing investigations of these systems.The literature held a puzzling discrepancy in which several similar reactants exhibited differing photochemistry.A series of 3-aryl-1,1,2,2-tetramethylcyclopropanes was found to rearrange photochemically to give primarily two types of products, the anticipated 4-aryl-2,3,3-trimethyl-1-butenes and, additionally, 1-aryl-2,3,3-trimethyl-1-butenes.The latter arise from regioselective methyl migration of intermediate singlet 1,3-diradicals.Also, the usual Griffin carbene fragmentation was encountered as a minor pathway.Biphenylyl-, p-cyanophenyl-, and p-anisyl-substituted cyclopropanes were studied.Also, the photochemistry of 3-phenyl-1,1,2,2-tetramethylcyclopropane was reinvestigated and found to conform to the general pattern of reactivity.Throughout, it was the singlet excited states responsible for the observed reactivity, and the triplet counterparts were found to be unreactive.In addition, the photochemistry of 3-biphenylyl-2,2-dimethyl-1,1-diphenylcyclopropane was studied.Again, the triplet was unreactive.The singlet gave rise to 4-biphenylyl-2-methyl-3,3-diphenyl-1-butene exclusively.The differing behavior of the various arylcyclopropanes is discussed from a mechanistic viewpoint.In the case of the 3-aryl-1,1,2,2-tetramethylcyclopropanes, the regioselectivity of the 1,3-diradical intermediate favors migration toward the less delocalized odd-electron center.This selectivity is understood on a quantum mechanical basis.Finally, quantum yields are reported.
- Zimmerman, Howard E.,Heydinger, Jenifer A.
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p. 1747 - 1758
(2007/10/02)
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- EFFECT OF MOLECULAR STRUCTURE ON OPTICAL PROPERTIES OF SYSTEMS CONTAINING CARBON CHIRALITY CENTERS. PART XXXII. 2-METHYL-3-(4'-BIPHENYLYL)-PROPIONIC ACIDS AND SOME OF THEIR DERIVATIVES
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The synthesis and principal properties of racemic 2-methyl-3-(4'-biphenyl)-propionic acid are descibed.The racemic acid was resolved into its optical antipodes.The absolute configurations of enantiomers were elucidated.Optical rotatory dispersion of the laevorotatory enantiomer, its amide and methylamide as well as its p-bromophenacyl and p-phenylphenacyl esters in the region 340λ600 nm was determined.Three-term equations describing optical rotation of the dextrorotatory enantiomer in the spectral region studied were determined.
- Janczewski, Marian,Pekalska, Janina
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p. 389 - 402
(2007/10/02)
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- Intramolecular Electron Transfer and SN2 Reactions in the Radical Anions of 1-(4-Biphenylyl)-ω-haloalkane Studied by Pulse Radiolysis
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One-electron reduction of 1-(4-biphenylyl)-ω-haloalkane (BPX-n) by solvated electrons and the intramolecular reactions of the radical anion thus formed have been investigated using the pulse-radiolysis technique.The spectrum observed immediately after the pulse has an absorption maximum at 410 nm which is assigned to the corresponding biphenyl radical anion.The decay behavior of all these 410-nm bands follows first-order kinetics and the rates are dependent on the methylene chain length, n.With BPCl-0 and BPCl-2, which provide large rate constants (7.5E7 and 1.7E8 s-1, respectively) and large G values of 4-alkylbiphenyl formation, an intramolecular electron transfer from a biphenyl radical anion to a C-Cl bond is presumed.The rate constants of the radical anions decrease in the order BPCl-1 > BPCl-2 > BPCl-0 which is roughly parallel to the C-Cl bond energy of these compounds and does not correlate with the chain length n, which corresponds to the distance required for the electron transfer.On the other hand, in the case of BPCl-3 and BPCl-4, the decay of the 410-nm band decreased about two orders of magnitude (5.5E5 and 1.2E6 s-1, respectively) and was characterized by a simultanous formation of a 330-nm band which is assigned to a spirocyclic radical.The G values of the corresponding 4-alkylbiphenyl formation were low for these compounds.On the basis of these observations, an intramolecular carbanionic displacement of the biphenyl radical anion on the chlorine center, which is a novel type of intramolecular SN2 reaction, has been concluded.Intramolecular reactions of bromo and iodo derivatives were also investigated and compared with those of corresponding chlorides.
- Kigawa, Hitoshi,Takamuku, Setsuo,Toki, Susumu,Kimura, Norio,Takeda, Seishi,et al.
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p. 5176 - 5179
(2007/10/02)
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