- Synthesis and characterization of N-phenyl pyrrole anchored to Fischer carbene complex through ring closing metathesis oxidative aromatization and various aryl substituted Fischer carbene complexes
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Ring closing metathesis of pentacarbonyl[(ethoxy)(N,N-diallyl anilyl)carbene]tungsten(0) complex, [(CO)5W=C(OCH2CH 3)C6H4N(CH2CHCH2) 2], 1 leads to the formation of pentacarbonyl[(ethoxy)(N-phenyl 2,5-dihydro pyrrolyl)carbene]tungsten(0) complex, [(CO)5W=C(OCH 2CH3)C6H4N (CH2CHCH 2)2], 2 in good yield. Further, complex 2 undergoes oxidative aromatization to afford N-phenyl pyrrole anchored to alkoxy carbene, 3. In addition, a number of aryl substituted carbene complexes [(CO) 5W=C(OCH2CH3)C6H4R], 4-7 (4: R = OCH2CH3; 5: R = OCH2CH=CH2; 6: R = OCH=CHCH2CH2CH2CH2CH 3; 7: OC6H5Br) have been synthesized from the reaction of 1-(allyloxy)-4-bromobenzene with W(CO)6 in presence of various concentration of n-BuLi and Meerwein's salt. All the complexes have been isolated in moderate to good yields and have been characterized by 1H NMR, 13C NMR, IR, UV-vis spectroscopic techniques and the solid state structures of 1, 2 and 4 have been unequivocally established by X-ray diffraction analysis.
- Ganesamoorthi,Thakur, Arunabha,Sharmila,Ramkumar,Ghosh, Sundargopal
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Read Online
- Design of new synthetic strategies to cyclophanes via ring-closing metathesis
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A simple synthetic methodology to cyclophanes containing hydroxyl groups has been reported. The key steps involved here are: Grignard reaction, double Claisen rearrangement, and ring-closing metathesis. The strategy reported here is protecting group-free synthesis.
- Kotha, Sambasivarao,Shirbhate, Mukesh E.
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Read Online
- Preparation method 3 - phenoxybromopropane or analogue thereof
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The invention discloses a preparation method of 3 -phenoxybromopropane or an analogue thereof, wherein 3 - phenoxybromopropane and an allyl compound thereof are obtained through substitution reaction and addition reaction so as to avoid the inconvenience of using gaseous hydrogen bromide, 2nd-step addition reaction is realized by using the brominated salt and the acid in situ, and the process is simple in operation. The condition is easy to control, the atom economy is good, the aspect of environmental impact is low pollution, zero emission accords with the current green chemical synthesis direction, and the cost is economic.
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Paragraph 0048-0050
(2021/11/26)
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- Aluminium chloride-potassium iodide-acetonitrile system: A mild reagent system for aromatic claisen rearrangement at ambient temperature
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Claisen rearrangement is used as the standard methods for the generation of complex organic substance. It is one of the well-known methods for the introduction of carbon-carbon bond. We have developed a protocol using allyl aryl ether as a substrate and AlCl3-KI as a mild reagent system and acetonitrile (CH3CN) is taken as solvent at ambient temperature. The reagent system presented in this current work is found to be appropriate for Claisen rearrangement of several aromatic alcohols with excellent yields.
- Bhattacharyya, Nayan Kamal,Dutta, Deepjyoti,Biswas, Joydeep
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- Nickel-catalyzed deallylation of aryl allyl ethers with hydrosilanes
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An efficient and mild catalytic deallylation method of aryl allyl ethers is developed, with commercially available Ni(COD)2 as catalyst precursor, simple substituted bipyridine as ligand and air-stable hydrosilanes. The process is compatible with a variety of functional groups and the desired phenol products can be obtained with excellent yields and selectivity. Besides, by detection or isolation of key intermediates, mechanism studies confirm that the deallylation undergoes η3-allylnickel intermediate pathway.
- Ding, Guangni,Fan, Sijie,Wang, Jingyang,Wang, Yu,Wu, Xiaoyu,Xie, Xiaomin,Yang, Liqun,Zhang, Zhaoguo
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supporting information
(2021/09/28)
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- NOVEL MACROCYCLIC DERIVATIVES, PROCESS FOR PREPARING SAME AND PHARMACEUTICAL COMPOSITIONS CONTAINING SAME
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Compound of formula (I): wherein A1, A2, Ra, Rb, Rc, Rd, R3, R4, X, Y and G are as defined in the description, and their use in the manufacture of medicaments.
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Paragraph 0470-0472; 0526; 0527
(2020/08/25)
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- Investigating the microwave-accelerated Claisen rearrangement of allyl aryl ethers: Scope of the catalysts, solvents, temperatures, and substrates
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The microwave-accelerated Claisen rearrangement of allyl aryl ethers was investigated, in order to gain insight into the scope of the catalysts, solvents, temperatures, and substrates. Among the catalysts examined, phosphomolybdic acid (PMA) was found to greatly accelerate the reaction in NMP, at temperatures ranging from 220 to 300 °C. This method was found to be useful for preparing several intermediates previously reported in the literature using precious metal catalysts such as Au(I), Ag(I), and Pt(II). Additionally, substrates bearing bromo and nitro groups on the aryl portion required careful tailoring of the reaction conditions to avoid complex product profiles.
- Hui, Zi,Jiang, Songwei,Qi, Xiang,Ye, Xiang-Yang,Xie, Tian
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supporting information
(2020/05/18)
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- Discovery and SAR of Natural-Product-Inspired RXR Agonists with Heterodimer Selectivity to PPARδ-RXR
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A known natural product, magnaldehyde B, was identified as an agonist of retinoid X receptor (RXR) α. Magnaldehyde B was isolated from Magnolia obovata (Magnoliaceae) and synthesized along with more potent analogs for screening of their RXRα agonistic activities. Structural optimization of magnaldehyde B resulted in the development of a candidate molecule that displayed a 440-fold increase in potency. Receptor-ligand docking simulations indicated that this molecule has the highest affinity with the ligand binding domain of RXRα among the analogs synthesized in this study. Furthermore, the selective activation of the peroxisome proliferator-activated receptor (PPAR) δ-RXR heterodimer with a stronger efficacy compared to those of PPARα-RXR and PPARγ-RXR was achieved in luciferase reporter assays using the PPAR response element driven reporter (PPRE-Luc). The PPARδactivity of the molecule was significantly inhibited by the antagonists of both RXR and PPARδ, whereas the activity of GW501516 was not affected by the RXR antagonist. Furthermore, the molecule exhibited a particularly weak PPARδagonistic activity in reporter gene assays using the Gal4 hybrid system. The obtained data therefore suggest that the weak PPARδagonistic activity of the optimized molecule is synergistically enhanced by its own RXR agonistic activity, indicating the potent agonistic activity of the PPARδ-RXR heterodimer.
- Nakashima, Ken-Ichi,Yamaguchi, Eiji,Noritake, Chihaya,Mitsugi, Yukari,Goto, Mayuki,Hirai, Takao,Abe, Naohito,Sakai, Eiji,Oyama, Masayoshi,Itoh, Akichika,Inoue, Makoto
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p. 1526 - 1534
(2020/05/19)
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- Concise and practical approach for the synthesis of honokiol, a neurotrophic agent
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An improved method has been developed for the synthesis of honokiol using a readily available p-bromophenol as a precursor. The key step involved in this method is ortho-lithiation facilitated by methoxymethyl ether (MOM). Other important steps are ortho-allyl phenyl ether Claisen rearrangement and a Suzuki coupling for the construction of biaryls. This method does not require pre-functionalization of aromatic ring with bromide for the generation of arylboronic acid.
- Khan, P. Rasvan,Mujawar, Taufiqueahmed,Shankar, G.,Shekhar, P.,Subba Reddy, BV.,Subramanyam, Ravi
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supporting information
(2020/08/06)
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- Highly regioselective O-allylation of phenol derivatives using MMZCu(I)Y catalyst
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A clean and effective method has been developed for the regioselective of O-allylation of phenol derivatives using a recyclable Cu(I)-exchanged multi-size porous material. Ease of preparation of catalyst through simple solid-state exchange and its compatibility in producing excellent amount of O-allylated products and a plausible mechanistic pathway for the regioselectivity are highlighted. This reported procedure is not requiring any external stabilizing ligand for Cu(I) species and further purification of products.
- Thangapriya, Cheirmakani,Ilaamirthamani, Simsonrubarathinam,Kumarraja, Mayilvasagam
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p. 361 - 367
(2019/12/11)
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- Enantioselective Synthesis of 3-Fluorochromanes via Iodine(I)/Iodine(III) Catalysis
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The chromane nucleus is common to a plenum of bioactive small molecules where it is frequently oxidized at position 3. Motivated by the importance of this position in conferring efficacy, and the prominence of bioisosterism in drug discovery, an iodine(I)/iodine(III) catalysis strategy to access enantioenriched 3-fluorochromanes is disclosed (up to 7:93 e.r.). In situ generation of ArIF2 enables the direct fluorocyclization of allyl phenyl ethers to generate novel scaffolds that manifest the stereoelectronic gauche effect. Mechanistic interrogation using deuterated probes confirms a stereospecific process consistent with a type IIinv pathway.
- Daniliuc, Constantin G.,Gilmour, Ryan,Neufeld, Jessica,Sarie, Jér?me C.,Thiehoff, Christian
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supporting information
p. 15069 - 15075
(2020/06/17)
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- Chemoselective Epoxidation of Allyloxybenzene by Hydrogen Peroxide Over MFI-Type Titanosilicate
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The chemoselective synthesis of 2-(phenoxymethyl)oxirane from allyloxybenzene is achieved with over 90 % yield in a sustainable reaction system using titanium-substituted silicalite-1 (TS-1) as a catalyst, hydrogen peroxide (H2O2) as an oxidant, and a mixture of MeOH/MeCN as a solvent at 40 °C. No acid-catalyzed side reactions prompted by the Lewis acidity of the Ti active site in TS-1 are observed. The TS-1 catalyst can also promote the formation of oxiranes from various p-substituted allyloxybenzenes in good yields. The reaction mechanism is investigated through the reaction with other allyloxy compounds. The results, which are supported by DFT calculations, indicate that an active species of Ti peroxides formed from the reaction of TS-1 with H2O2 selectively oxidizes the allyloxybenzene to 2-(phenoxymethyl)oxirane.
- Fujitani, Tadahiro,Hong, Dachao,Ito, Satoru,Ji, Xinyi,Kon, Yoshihiro,Nakashima, Takuya,Osuga, Ryota,Sato, Kazuhiko,Yokoi, Toshiyuki
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supporting information
(2020/04/15)
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- Enantioselective Construction of Si-Stereogenic Center via Rhodium-Catalyzed Intermolecular Hydrosilylation of Alkene
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Catalytic, enantioselective synthesis of stereogenic silicon compounds remains a challenge. Herein, we report a rhodium-catalyzed regio- and enantio-selective intermolecular hydrosilylation of alkene with prochiral dihydrosilane. This new method features a simple catalytic system, mild reaction conditions and a wide functional group tolerance.
- He, Tao,Liu, Li-Chuan,Ma, Wen-Peng,Li, Bin,Zhang, Qing-Wei,He, Wei
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supporting information
p. 17011 - 17015
(2020/11/30)
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- Nano-dispersed platinum(0) in organically modified silicate matrices as sustainable catalysts for a regioselective hydrosilylation of alkenes and alkynes
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Nano-dispersed platinum(0) particles stabilized in a range of organically modified silicate (ORMOSIL) matrices are investigated as sustainable catalysts for the hydrosilylation of alkenes and alkynes. In this study, five different siloxane matrices including triethoxysilane (HTEOS), methyltriethoxysilane (MTES), ethyltriethoxysilane (ETES), triethoxyvinylsilane (TEVS) and propyltriethoxysilane (PTES) are investigated, and the distribution of the metal particles in these materials analyzed by transition electron microscopy (TEM). The particles appeared to be generally of a small size, with a diameter of ca. 2-5 nm in each of these catalysts, however the distribution is not equally uniform from one matrix to the other. HTEOS, MTES and ETES that respectively carry a hydrogen, a methyl and an ethyl group on the triethoxysilane moiety, displayed a more uniform distribution, while particles appeared to be more scattered in the remaining matrices. Catalysts with a uniform particles distribution produced higher and consistent yields, while those with poor particles distribution produced lower and almost random yields, suggesting that the uniformity in particle distribution, and by extension the nature of the siloxane matrix, are important for the catalytic properties of these materials. The scope of the reaction was broadened to a range of olefins, with a goal of investigating the tolerability of the reaction toward a number of reactive functional groups, resulting in the preparation of 28 compounds. This catalytic system also enabled the hydrosilylation of a limited number of alkynes under the optimized reaction conditions.
- Duke, Brett J.,Akeroyd, Evan N.,Bhatt, Shreeja V.,Onyeagusi, Chibueze I.,Bhatt, Shreya V.,Adolph, Brandy R.,Fotie, Jean
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p. 11782 - 11795
(2018/07/25)
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- Dimethyldioxirane (DMDO) as a valuable oxidant for the synthesis of polyfunctional aromatic imidazolium monomers bearing epoxides
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Conventional organic salts represent a new paradigm in many areas of research. Despite their great potential, an improvement in their physicochemical properties requires the chemical modification of their intrinsic structure. Thus, an efficient pathway was developed for the preparation of polyfunctional imidazolium monomers incorporating aromatic rings and terminal epoxides which presented a real synthetic challenge. In this work, we describe the reactivity of various oxidizing agents to develop a strong, clean and powerful methodology to generate epoxidized salts. Various reaction conditions for the formation of the epoxides were investigated such as the role of the cation and the counterion as well as the influence of an aromatic and/or aliphatic linker chain. Finally, we have evaluated the thermal properties of these new polyfunctional salts by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC).
- Chardin,Rouden,Livi,Baudoux
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supporting information
p. 5054 - 5059
(2017/11/09)
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- Palladium-Catalyzed Fluoroalkylative Cyclization of Olefins
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A palladium-catalyzed fluoroalkylative cyclization of olefins with readily available Rf-I reagents to afford the corresponding fluoroalkylated 2,3-dihydrobenzofuran and indolin derivatives with moderate to excellent yields is reported. This novel procedure provides an efficient method for the construction of Csp3-CF2 and C-O/N bonds in one step. A wide range of functional groups are tolerated. It is proposed that a radical/SET (single electron transfer) pathway proceeding via the fluoroalkyl radical may be involved in the catalytic cycle.
- Liao, Jianhua,Fan, Lianfeng,Guo, Wei,Zhang, Zhenming,Li, Jiawei,Zhu, Chuanle,Ren, Yanwei,Wu, Wanqing,Jiang, Huanfeng
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supporting information
p. 1008 - 1011
(2017/03/15)
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- Visible-light-induced thiotrifluoromethylation of terminal alkenes with sodium triflinate and benzenesulfonothioates
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An unconventional reductive quenching cycle was developed to realize the visible-light-induced thiotrifluoromethylation of terminal alkenes. CF3SO2Na was used as an easy to handle CF3 radical source to afford the desired products in moderate to good yields. Mild reaction conditions and a broad substrate scope feature in this transformation.
- Kong, Weiguang,An, Hejun,Song, Qiuling
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supporting information
p. 8968 - 8971
(2017/08/15)
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- Catalytic Difluorination of Olefins
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Molecular editing with fluorine is a validated strategy for modulating the structure and function of organic systems. In the current arsenal of catalytic dihalogenation technologies, the direct generation of the vicinal difluoride moiety from simple olefins without a prefunctionalization step remains conspicuously absent. Herein we report a catalytic, vicinal difluorination of olefins displaying broad functional group tolerance, using inexpensive p-iodotoluene as the catalyst. Preliminary efforts toward the development of an enantioselective variant are also disclosed.
- Molnár, István Gábor,Gilmour, Ryan
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supporting information
p. 5004 - 5007
(2016/05/19)
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- Sodium Perborate: A Facile Catalyst for Allylation of Active Centers
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An efficient and ecofriendly allylation of O-H, N-H, and C-H groups has been achieved successfully with the reaction of allyl bromide by using sodium perborate as a new catalyst in aqueous media. The advantage of this method is operationally simple, short reaction time, good yield, and simple workup conditions over the previously reported conventional methods such as amination, oxyalkylation reactions of allyl bromide, and Friedel-Crafts allylation chemistry.
- Jayaprakash, Soora Harinath,Krishna, Balam Satheesh,Prasad, Sthanikam Siva,Sudha, Sarva Santhi,Reddy, Cirandur Suresh
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supporting information
p. 355 - 362
(2015/10/29)
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- Enantioselective synthesis of benzofurans and benzoxazines via an olefin cross-metathesis-intramolecular oxo-Michael reaction
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Chiral phosphoric acid and Hoveyda-Grubbs II were found to catalyze an olefin cross-metathesis-intramolecular oxo-Michael cascade reaction of the ortho-allylphenols and enones to provide a variety of benzofuran and benzoxazine derivatives in moderate to good yields and enantioselectivity.
- Zhang, Jun-Wei,Cai, Quan,Gu, Qing,Shi, Xiao-Xin,You, Shu-Li
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supporting information
p. 7750 - 7752
(2013/09/02)
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- Design, synthesis, and anti-proliferative evaluation of [1,1′-biphenyl]-4-ols as inhibitor of HUVEC migration and tube formation
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Allylated biphenol neolignans contain a variety of chemopreventive entities that have been used as anti-tumor drug leads. Herein, 37 allylated biphenols were evaluated for anti-proliferative activity by the MTT assay and inhibitory effect on the migration and tube formation of HUVECs featuring anti-angiogenic properties. 3-(2-Methylbut-3-en-2-yl)-3′,5′-bis(trifluoromethyl)-[1, 1′-biphenyl]-4-ol (5c) exerted an inhibitory effect on HUVECs compared to honokiol (IC50 = 47.0 vs. 52.6 μM) and showed significant blocking effects on the proliferation of C26, Hela, K562, A549, and HepG2 (IC 50 = 15.0, 25.0, 21.2, 29.5, and 13.0 μM, respectively), superior to those of honokiol (IC50 = 65.1, 62.0, 42.0, 75.0, and 55.4 μM, respectively). Importantly, compound 5c inhibited the migration and capillary-like tube formation of HUVECs in vitro.
- Ran, Yan,Ma, Liang,Wang, Xuewei,Chen, Jinying,Wang, Guangcheng,Peng, Aihua,Chen, Lijuan
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experimental part
p. 8091 - 8104
(2012/10/07)
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- Structural modification of honokiol, a biphenyl occurring in magnolia officinalis: The evaluation of honokiol analogues as inhibitors of angiogenesis and for their cytotoxicity and structure-activity relationship
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Honokiol, widely known as an antitumor agent, has been used as an antiangiogenesis drug lead. In this paper, 47 honokiol analogues and derivatives were investigated for their antiangiogenic activity by application of the transgenic zebrafish screening model, antiproliferative and cytotoxic activity against HUVECs, and three tumor cell lines by MTT assay. 3′,5-Diallyl-2, 4′-dihydroxy-[1,1′-biphen-yl]-3,5′-dicarbaldehyde (8c) was found to suppress the newly grown segmental vessels from the dorsal aorta of zebrafish and prevent inappropriate vascularization as well as exhibit more potent inhibitory effects on the proliferation of HUVECs, A549, HepG2, and LL/2 cells (IC50 = 15.1, 30.2, 10.7, and 21.7 μM, respectively) than honokiol (IC50 = 52.6, 35.0, 16.5, and 65.4 μM, respectively). Analogue 8c also effectively inhibited the migration and capillary-like tube formation of HUVECs in vitro. The antiangiogenic effect and antiproliferative activity of these structurally modified honokiol analogues and derivatives have led to the establishment of a structure-activity relationship.
- Ma, Liang,Chen, Jinying,Wang, Xuewei,Liang, Xiaolin,Luo, Youfu,Zhu, Wei,Wang, Tianen,Peng, Ming,Li, Shucai,Jie, Shi,Peng, Aihua,Wei, Yuquan,Chen, Lijuan
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experimental part
p. 6469 - 6481
(2011/12/01)
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- Synthesis of new cores and their use in the preparation of polyester dendrimers
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Six dendrimer and dendron cores terminated by hydroxyl groups that are neither phenolic nor cleavable by hydrogenolysis have been prepared in a consistent one-pot manner from terminal allyl groups by reduction of the product of reductive ozonolysis. Some of the terminal allyl derivatives are new and others have been prepared by new methods. The well-known O-benzylidene derivative of 2,2′-bis(hydroxymethyl)propanoic acid was shown to be the cis-stereoisomer. A new AB3-type anhydride, tris(benzyloxymethyl) acetic anhydride has been prepared. It was demonstrated that these cores and dendrons could be assembled into first and second generation homo- and mixed polyester dendrimers.
- Twibanire, Jean-D'Amour K.,Al-Mughaid, Hussein,Grindley, T. Bruce
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experimental part
p. 9602 - 9609
(2011/01/03)
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- Microwave activation of alumina and its use as a catalyst in synthetic reactions
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Microwave irradiation is a simple and efficient method of activating gamma alumina. Alumina activated in this manner is an excellent medium in which to carry out the Diels-Alder reaction and, in conjunction with additional microwave irradiation, the Claisen rearrangement. Several 2-allylphenols formed in the Claisen rearrangement rapidly undergo ring closure on alumina to form dihydrobenzofurans demonstrating the Br0nsted acidity of the solid.
- Dadush, Eric,Green, James F.,Sease, Aaron,Naravane, Abhijit,Pagni, Richard M.,Kabalka, George W.
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experimental part
p. 120 - 123
(2010/02/28)
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- COMPOUND, ALPHA 1 ADRENALINE RECEPTOR ANTAGONIST, AND COMPOSITION
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A novel compound, a novel α1 adrenergic receptor antagonistic agent, and a novel composition are provided which are capable of exerting a therapeutic effect on treatment of hypertension as well as treatment of prostatic hypertrophy and the like. The compound is represented by the following formula (1):
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Page/Page column 13-14; 26
(2009/12/23)
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- Regioselective photochemical and microwave mediated monobromination of aromatic compounds using 2,4,4,6-tetrabromo-2,5-cyclohexadienone
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Bromination of different aromatic substrates have been described using 2,4,4,6-tetrabromo-2,5-cyclohexadienone in conjunction with microwave and ultraviolet radiations. Important features of the work include high regioselectivity obtained in very short to moderate reaction time, atom economy, and recyclability of the reagent. Copyright Taylor & Francis Group, LLC.
- Gupta, Neeraj,Kad, Goverdhan L.,Singh, Vasundhara,Singh, Jasvinder
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p. 3421 - 3428
(2008/02/12)
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- 1-(PIPERIDIN-4-YL)-1H-INDOLE DERIVATIVE
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The present invention provides a compound represented by the formula (1) or a pharmacologically acceptable salt thereof, or a hydrate thereof (provided that a compound in which all of R4a, R4b, and R4c are hydrogen atoms is excluded.): [wherein R1 represents a hydrogen atom, R2 represents a hydrogen atom, R3 represents the formula: wherein R4a, R4b, and R4c are the same as or different from each other and each represents a hydrogen atom, a C1-6 alkyl group or a C1-6 alkoxy group, etc.]
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Page/Page column 35-36
(2010/11/28)
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- Chemoselective hydrogenation method catalyzed by Pd/C using diphenylsulfide as a reasonable catalyst poison
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While Pd/C is one of the most useful catalysts for hydrogenation, the high catalyst activity of Pd/C causes difficulty in its application to chemoselective hydrogenation between different types of reducible functionalities. In order to achieve chemoselective hydrogenation using Pd/C, we investigated catalyst poison as a controller of the catalyst activity. We found that the addition of Ph2S (diphenylsulfide) to the Pd/C-catalyzed hydrogenation reaction mixture led to reasonable deactivation of Pd/C. By the use of the Pd/C-Ph2S catalytic system, olefins, acetylenes, and azides can be selectively reduced in the coexistence of aromatic carbonyls, aromatic halides, cyano groups, benzyl esters, and N-Cbz (benzyloxycarbonyl) protecting groups. The present method is promising as a general and practical chemoselective hydrogenation process in synthetic organic chemistry.
- Mori, Akinori,Mizusaki, Tomoteru,Miyakawa, Yumi,Ohashi, Eri,Haga, Tomoko,Maegawa, Tomohiro,Monguchi, Yasunari,Sajiki, Hironao
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p. 11925 - 11932
(2007/10/03)
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- Azidosubstituted arylboronic acids: Synthesis and Suzuki-Miyaura cross-coupling reactions
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Arylboronic acids having a remote azido group were prepared from the corresponding azidosubstituted aryl bromides via lithiation and treatment with trialkyl borates. Preparative yields were achieved when the starting aryl bromides possessed ortho-alkoxy groups, which would stabilize the intermediate aryllithium species. Conventional Suzuki cross-coupling of the arylboronic acids proceeded generally well with retention of azido group; however, sometimes azidomethyl fragment underwent oxidative transformation into a nitrile.
- Sviridov, Sergey I.,Vasil'ev, Andrei A.,Sergovskaya, Natalia L.,Chirskaya, Marina V.,Shorshnev, Sergey V.
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p. 2639 - 2647
(2007/10/03)
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- An isomerization-ring-closing metathesis strategy for the synthesis of substituted benzofurans
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Twelve substituted benzofurans were synthesized from their corresponding substituted 1-allyl-2-allyloxybenzenes using ruthenium-mediated C- and O-allyl isomerization followed by ring-closing metathesis.
- Van Otterlo, Willem A.L.,Morgans, Garreth L.,Madeley, Lee G.,Kuzvidza, Samuel,Moleele, Simon S.,Thornton, Natalie,De Koning, Charles B.
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p. 7746 - 7755
(2007/10/03)
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- Total synthesis of (-)-ephedradine A: An efficient construction of optically active dihydrobenzofuran-ring via C-H insertion reaction
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The stereocontrolled total synthesis of (-)-ephedradine A (1) has been accomplished. Construction of optically active dihydrobenzofuran-ring was performed by a novel asymmetric C-H insertion reaction. After an intramolecular ester-amide exchange reaction and a Sharpless asymmetric aminohydroxylation reaction, construction of the complex macrocyclic ring was performed by Ns-strategy and an intramolecular aza-Wittig reaction. Graphical Abstract.
- Kurosawa, Wataru,Kobayashi, Hideki,Kan, Toshiyuki,Fukuyama, Tohru
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p. 9615 - 9628
(2007/10/03)
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- Facile and selective deallylation of allyl ethers using diphosphinidenecyclobutene-coordinated palladium catalysts
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(π-Allyl)palladium triflate bearing a 1,2-bis(4-methoxyphenyl)-3,4- bis(2,4,6-tri-tert-butylphenylphosphinidene)cyclobutene ligand (DPCB-OMe), [Pd(η3-C3H5)(DPCB-OMe)]OTf, efficiently catalyzes deallylation of a variety of allyl ethers in aniline to give corresponding alcohols in high yields under mild conditions. The reactions can be performed in air without loss of a variety of functionalities including vinyl, alkynyl, hydroxy, acetoxy, silyloxy, and acetal groups. Allyl 2-allyloxybenzoate selectively undergoes deallylation of the allyloxy group to give allyl salicylate in quantitative yield.
- Murakami, Hiromi,Minami, Tatsuya,Ozawa, Fumiyuki
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p. 4482 - 4486
(2007/10/03)
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- Ortho- and para-substituted Hoveyda-Grubbs carbenes. An improved synthesis of highly efficient metathesis initiators
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A novel highly efficient and general route to various 3- and 5-substituted 2-alkoxystyrenes, required for the preparation of Hoveyda-Grubbs catalysts, is described.
- Bujok, Robert,Bieniek, Michal,Masnyk, Marek,Michrowska, Anna,Sarosiek, Agata,Stepowska, Halszka,Arlt, Dieter,Grela, Karol
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p. 6894 - 6896
(2007/10/03)
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- An efficient synthesis of optically active trans-2-Aryl-2,3-dihydrobenzofuran-3-carboxylic acid esters via C-H insertion reaction
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Optically active trans-2-Aryl-2,3-dihydrobenzofuran-3-carboxylic acid esters were synthesized by intramolecular C-H insertion reaction. Upon treatment with a catalytic amount of Rh2(R-DOSP)4, aryldiazoester 8c possessing a chiral auxiliary underwent C-H insertion reaction to give 9c in high yield and in high selectivity (84% yield, 86% de).
- Kurosawa, Wataru,Kan, Toshiyuki,Fukuyama, Tohru
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p. 1028 - 1030
(2007/10/03)
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- Stereocontrolled total synthesis of (-)-ephedradine a (orantine)
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The stereocontrolled total synthesis of (-)-ephedradine A has been accomplished. The synthesis features an asymmetric C-H insertion reaction, an intramolecular ester-amide exchange reaction, and a Sharpless asymmetric aminohydroxylation reaction. Construction of the complex macrocyclic ring was performed by Ns-strategy and an intramolecular aza-Wittig reaction. Copyright
- Kurosawa, Wataru,Kan, Toshiyuki,Fukuyama, Tohru
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p. 8112 - 8113
(2007/10/03)
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- Thermodynamic, spectroscopic, and density functional theory studies of allyl aryl and prop-1-enyl aryl ethers. Part 1. Thermodynamic data of isomerization
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A chemical equilibration study of the relative thermodynamic stabilities of seventy isomeric allyl aryl ethers (a) and (Z)-prop-1-enyl aryl ethers (b) in DMSO solution has been carried out. From the variation of the equilibrium constant with temperature the Gibbs energies, enthalpies, and entropies of isomerization at 298.15 K have been evaluated. Because of their low enthalpies, the (Z)-prop-1-enyl aryl ethers are strongly favored at equilibrium, the Gibbs energies of the a→b isomerization ranging from -12 to -23 kJ mol-1. The entropy contribution is negligible in most reactions, but occasionally small positive values less than +10 J K-1 mol-1 of the entropy of isomerization are found. The equilibration studies were also extended to involve two pairs of related isomeric ethers with a Me substituent on C(2) of the olefinic bond. The Me substituent was found to increase the relative thermodynamic stability of the allylic ethers by ca. 3.4 kJ mol-1.
- Taskinen, Esko
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p. 1824 - 1834
(2007/10/03)
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- Design of liquid crystalline block molecules with nonconventional mesophase morphologies: Calamitic bolaamphiphiles with lateral alkyl chains
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Novel bolaamphiphiles, consisting of a biphenyl rigid core, polar 2,3-dihydroxypropoxy groups at each terminal end, and an additional long alkyl chain in a lateral position have been synthesized. The structures of these ternary block molecules were systematically changed by variation of the length and position of the alkyl chain, by introduction of additional spacer units between one of the 2,3-dihydroxypropyl groups and the rigid core, and by replacement of one of the 2,3-dihydroxypropoxy groups by a single hydroxy group. The influence of these structural variations on the liquid crystalline properties of these new materials was investigated by polarized-light microscopy, differential scanning calorimetry, and X-ray diffraction. These investigation have shown that, by elongation of the lateral chain, a transition from a smectic monolayer structure (SmA1) via a strongly distorted layer structure (SmA+), a centered rectangular columnar phase (Colr/c2mm) and a noncentered rectangular columnar phase (Colr/p2gg) to a hexagonal columnar phase (Colh/p6mm) takes place. Elongation of the bolaamphiphilic core leads to the loss of the columnar phases, which are replaced by smectic phases, whereas reduction of its length favors the hexagonal columnar phase. This phase sequence is explained as a result of the microsegregation of the lateral alkyl chains from the rigid aromatic cores. The segregated alkyl chains are organized in columns that interrupt the smectic layers. The hydrogen bonding keep the bolaamphiphilic cores fixed end to end, so that they form networks of cylinders around the lipophilic columns. The space required by the alkyl chains with respect to the length of the bolaamphiphilic cores is restricted and largely determines the geometry of the cylinders, which leads to the observed phase sequence. The obtained mesophase morphologies, built up by three distinct sets of subspaces, are related to morphologies of some ternary block copolymers. Furthermore, the investigated compounds represent a novel class of materials, capable of forming supramolecular columnar mesophases.
- Koelbel,Beyersdorff,Xiao Hong Cheng,Tschierske,Kain,Diele
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p. 6809 - 6818
(2007/10/03)
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- Asymmetric synthesis of the northern segment of ephedradine C
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An asymmetric synthesis of the dihydrobenzofuran segment of ephedradine C has been achieved. Key steps include a chiral oxazolidinone-mediated aldol reaction to form a β-hydroxy ester, followed by a novel debenzylation and concomitant intramolecular cyclisation with iodotrimethylsilane. An asymmetric Michael reaction with a homochiral lithium amide was used to form the third and final chiral centre. The absolute stereochemistry of these three centres was confirmed by X-ray crystal-structure determinations.
- Russell, Michael G.N.,Baker, Raymond,Ball, Richard G.,Thomas, Steven R.,Tsou, Nancy N.,Castro, Jose L.
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p. 893 - 899
(2007/10/03)
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- Asymmetric synthesis of the northern segment of ephedradine C. A novel dihydrobenzo[b]furan formation
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An asymmetric synthesis of the dihydrobenzo[b]furan segment of ephedradine C has been achieved utilising a chiral oxazolidinone in an aldol reaction to form a ?2-hydroxy ester, followed by a novel debenzylation and concomitant intramolecular cyclisation with iodotrimethylsilane as key steps. An asymmetric Michael reaction with a homochiral lithium amide was used to form the third and final chiral centre.
- Russell, Michael G. N.,Baker, Raymond,Castro, Joseì? L.
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p. 8667 - 8670
(2007/10/03)
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- Kaolin-assisted Aromatic Chlorination and Bromination
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Moist kaolin catalyses the regioselective and high-yielding chlorination and bromination of C6H5OR (R = C1-C8 alkyl. Bu1, allyl, cyclohexyl, benzyl) to 4-XC6H4OR (X = Cl and Br, respectively) with NaCl02 and Mn(acac)3 in CH2Cl2 in the absence and presence of NaBr, respectively, under mild and neutral conditions.
- Hirano, Masao,Monobe, Hiroyuki,Yakabe, Shigetaka,Morimoto, Takashi
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p. 662 - 663
(2007/10/03)
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- Convenient criterion for the distinction between electrophilic and electron transfer reactions of electron-rich alkenes
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Both experimental and theoretical studies confirm that the formation of aryl vinyl ether and aryl vinyl sulfide cation radicals from the corresponding neutral substrates correlates with the Brown σ+ parameters as opposed to Hammett σ values. Peak oxidation potentials for both classes of substrates correlate preferentially with σ+, as do gas-phase ionization energies calculated by both semi-empirical and ab initio methods. In contrast, the protonation energies of the same substrates, which relate to carbocation formation, correlate preferentially with σ values, as do rates of protonation and other electrophilic additions. These observations permit a sharp distinction between electrophilic and electron transfer reactions of these two common classes of electron-rich substrates. Using this criterion, the cycloadditions of tetracyanoethylene to these substrates are found to proceed via an electrophilic mechanism, rather than by a previously proposed electron transfer mechanism.
- Bauld, Nathan L.,Aplin, J. Todd,Yueh, Wang,Endo, Stephanie,Loving, Angie
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- Highly Efficient and Convenient Methods for the Direct Conversion of Aryl Silyl Ethers and Aryl Acetates into Aryl Alkyl Ethers
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Direct conversion of aryl trialkylsilyl ethers and aryl acetates into the corresponding alkyl-protected phenols such as benzyl and allyl ethers can be conveniently performed by the reaction with alkyl halide in the presence of cesium fluoride and sodium methoxide, respectively, in a one-pot procedure.
- Oriyama, Takeshi,Noda, Kojiro,Yatabe, Kaori
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p. 701 - 703
(2007/10/03)
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- Total synthesis of the phenylpropanoid glycoside, grayanoside A
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Grayanoside A, 2-(4-hydroxyphenyl)ethyl 6-O-feruloyl-β-D-glucopyranoside, was synthesized for the first time by using chloroacetyl groups for the protection of hydroxy functions. 2-(4-Allyloxyphenyl)ethyl 4-O-[(4-O-allyl)feruloyl]-2,3,6-tri-O-chloroacetyl-β-D-glucopyranoside (12) was synthesized from 2-(4-allyloxyphenyl)ethyl 4,6-O-benzylidene-β-D-glucopyranoside (8) in four steps with the goal of preparing syringalide B. It was found, however, that the feruloyl group migrated from the 4- to the 6-position of the glycopyranoside during the deprotection of 12.
- Zhang, San-Qi,Li, Zhong-Jun,Wang, An-Bang,Meng-Shen, Cai,Feng, Rui
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p. 281 - 285
(2007/10/03)
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- ACETYLENE DERIVATIVES HAVING LIPOXYGENASE INHIBITORY ACTIVITY
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Compounds of the structure where p and q are zero or one, but cannot both be the same, M is a pharmaceutically acceptable cation or a metabolically cleavable group, B is a valence bond or a straight or branched alkylene group, R is alkyl, cycloalkyl or --NR1 R2, where R1 and R2 are hydrogen, alkyl, cycloalkyl or alkanoyl, and A is optionally substituted carbocyclic aryl, furyl, benzo[b]furyl, thienyl, or benzo[b]thienyl are potent inhibitors of lipoxygenase enzymes and thus inhibit the biosynthesis of leukotrienes. These compounds are useful in the treatment or amelioration of allergic and inflammatory disease states.
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- Phase-transfer catalyzed nucleophilic addition of arylalkanenitrile carbanions to substituted propenylarenes
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Phenylacetonitrile and 2-phenylalkanenitriles react under phase transfer catalysis conditions with 2-propenylanisoles containing electron-withdrawing substituents (or their corresponding precursors, 2-allylanisoles) via the Michael addition pathway to give substituted 4-aryl-2-phenylbutyronitriles.
- Lasek,Makosza
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p. 780 - 782
(2007/10/02)
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- A new and facile synthesis of chroman-3-ols, 3,4-dihydro-2H-[1]-benzopyran-3-ols
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o-Allyl phenols react with m-chloroperoxybenzoic acid (m-CPBA) in dry chloroform to give chroman-3-ols in a single step in good yields (93-96%).
- Satyanarayana,Prasad Rao Ch.,Krupadanam,Srimannarayana
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p. 1455 - 1464
(2007/10/02)
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- Phenyl substituted-2,4,6,8-nonatetraenoic acid
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The compounds 9-phenyl-3,7-dimethyl-2,4,6,8 nonatetraenoic acids wherein the phenyl group is substituted with an alkyl, aminoalkyl, hydroxyalkyl, alkoxy, hydroxyalkylamino, and a hydroxy alkoxy group, and derivatives thereof which are used as disease modifying anti-rheumatic agents and as immunosuppressants.
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- Kinetics and Mechanism of Reactions of Sodium Phenoxides with Allyl Halides
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Kinetics of reactions of sodium phenoxides with allyl chloride and allyl bromide in aprotic solvent mixtures have been reported.The reactions are overall second order processes.The reaction results in an O-alkylated product.Protic solvents retard the reaction.A mechanism commensurate with the kinetic data has been suggested.
- Panigrahi, G. P.,Sinha, T. K.
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- α-Adrenoreceptor Reagents. 2. Effects of Modification of the 1,4-Benzodioxan Ring System on α-Adrenoreceptor Activity
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Modification of the 1,4-benzodioxan ring present in RX 781094 (1) has not previously been considered.This paper describes a number of analogues of this ring system, including compounds in which one of the oxygen atoms has been replaced by a methylene group and also those in which the ring size has been changed to give, for example, furan and thiophene derivatives.The dihydroxybenzofuranylimidazoline compound 7 is the only analogue possesing presynaptic antagonist potency and selectivity comparable to that of 1.In view of this result, a number of derivatives was prepared to determine the structure-activity relationships within this series.Many derivatives, as well as the parent compound 7, were found to possess presynaptic α2-adrenoreceptor antagonist and postsynaptic α1-adrenoreceptor partial agonist properties.Two of the selective presynaptic antagonists,13 and 14, possess greater potency and selectivity than that possessed by 1.The 5-chloro derivative 25 is twice as potent as 1 after oral administration but only about half as potent when given intravenously.
- Chapleo, Christopher B.,Myers, Peter L.,Butler, Richard C. M.,Davis, John A.,Doxey, John C.,et al.
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p. 570 - 576
(2007/10/02)
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