- A new insight into the push-pull effect of substituents via the stilbene-like model compounds
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In this paper, authors report on 1-pyridyl-2-arylethenes, 1-furyl-2-arylethylenes, 1,2-diphenylpropylenes and substituted cinnamyl anilines as stilbene-like model compounds to investigate the factors dominating the push-pull effect of substituents via usi
- Cao, Chaotun,Cao, Chenzhong,Zeng, Zhao
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- Determination and application of the excited-state substituent constants of pyridyl and substituted phenyl groups
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Thirty six 1-pyridyl-2-arylethenes XCH=CHArY (abbreviated XAEY) were synthesized, in which, X is 2-pyridyl, 3-pyridyl and 4-pyridyl and Y is OMe, Me, H, Br, Cl, F, CF3, and CN. Their ultraviolet absorption spectra were measured in anhydrous ethanol, and their wavelengths of absorption maximum λmax were recorded. Also, the 234 λmax values of 1-substituted phenyl-2-arylethylene compounds (XAEY, where X is substituted phenyl) were collected. The excited-state substituent constants (Formula presented.) of three pyridyl groups and 23 substituted phenyl groups (total of 26) were obtained by means of curve-fitting method. Taking the λmax values of 358 samples of bi-arylethene derivatives as a data set and 126 samples of bi-aryl Schiff bases (including nine compounds synthesized by this work) as another data set, quantitative correlation analyses were performed by employing the obtained (Formula presented.) as a parameter, and good results were obtained for the two data sets. The reliability of the obtained (Formula presented.) values was verified. The results of this paper can provide excited-state substituent constants for the study and application of optical properties of conjugated organic compounds containing aryl groups.
- Cao, Chao-Tun,Yan, Lu,Cao, Chenzhong
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- Water-Sculpting of a Heterogeneous Nanoparticle Precatalyst for Mizoroki-Heck Couplings under Aqueous Micellar Catalysis Conditions
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Powdery, spherical nanoparticles (NPs) containing ppm levels of palladium ligated by t-Bu3P, derived from FeCl3, upon simple exposure to water undergo a remarkable alteration in their morphology leading to nanorods that catalyze Mizoroki-Heck (MH) couplings. Such NP alteration is general, shown to occur with three unrelated phosphine ligand-containing NPs. Each catalyst has been studied using X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), and cryogenic transmission electron microscopy (cryo-TEM) analyses. Couplings that rely specifically on NPs containing t-Bu3P-ligated Pd occur under aqueous micellar catalysis conditions between room temperature and 45 °C, and show broad substrate scope. Other key features associated with this new technology include low residual Pd in the product, recycling of the aqueous reaction medium, and an associated low E Factor. Synthesis of the precursor to galipinine, a member of the Hancock family of alkaloids, is suggestive of potential industrial applications.
- Pang, Haobo,Hu, Yuting,Yu, Julie,Gallou, Fabrice,Lipshutz, Bruce H.
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supporting information
p. 3373 - 3382
(2021/04/07)
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- Dual ligand-promoted palladium-catalyzed nondirected C-H alkenylation of aryl ethers
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Direct C-H functionalization of aryl ethers remains challenging owing to their low reactivity and selectivity. Herein, a novel strategy for nondirected C-H alkenylation of aryl ethers promoted by a dual ligand catalyst was demonstrated. This catalytic system readily achieved the highly efficient alkenylation of alkyl aryl ethers (anisole, phenetole, n-propyl phenyl ether, n-butyl phenyl ether and benzyl phenyl ether), cyclic aryl ethers (1,4-benzodioxan, 2,3-dihydrobenzofuran, dibenzofuran), and diphenyl oxides. Moreover, the proposed methodology was successfully employed for the late-stage modification of complex drugs containing the aryl ether motif. Interestingly, the compounds developed herein displayed fluorescent properties, which would facilitate their biological applications.
- Fu, Manlin,Liu, Jiang,Wang, Lei,Yin, Biao,Zhu, Qing
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supporting information
p. 3293 - 3296
(2020/04/02)
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- Iron-Catalyzed Coupling of Methyl N-Heteroarenes with Primary Alcohols: Direct Access to E-Selective Olefins
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An efficient Fe-catalyzed system is reported for direct α-olefination of methyl-substituted N-heteroarenes with primary alcohols. The catalytic dehydrogenative coupling enables a series of functionalized E-olefinated N-heteroaromatics with excellent selectivity (>99%). Initial mechanistic studies including deuterium-labeling experiments provide evidence for the participation of the benzylic C-H/D bond of alcohols.
- Das, Jagadish,Vellakkaran, Mari,Sk, Motahar,Banerjee, Debasis
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supporting information
p. 7514 - 7518
(2019/10/02)
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- Nickel-catalysed direct α-olefination of alkyl substituted N-heteroarenes with alcohols
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Catalytic α-olefination of alkylheteroarenes with primary alcohols via dehydrogenative coupling is presented. A simple nickel catalyst system stabilised by readily available nitrogen ligands enables a series of interesting E-configured vinylarenes (confirmed by X-ray crystal-structure analysis) to be synthesised in good to excellent yields with olefin/alkane selectivity of >20:1. Hydrogen and water are generated as byproducts and quantitative determination of H2 was performed.
- Das, Jagadish,Vellakkaran, Mari,Banerjee, Debasis
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supporting information
p. 7530 - 7533
(2019/07/04)
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- Br?nsted acid-catalysed conjugate addition of photochemically generated α-amino radicals to alkenylpyridines
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The conjugate addition of α-amino radicals to alkenylpyridines has been accomplished by the synergistic merger of Br?nsted acid and visible light photoredox catalysis. Key to reaction development was the protonation of the alkenylpyridines that transientl
- Hepburn, Hamish B.,Melchiorre, Paolo
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supporting information
p. 3520 - 3523
(2016/03/04)
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- Palladium-Catalyzed Oxidative Heck Coupling of Vinyl Pyridines with Aryl Boronic Acids
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An efficient methodology has been developed for the oxidative cross-coupling of vinyl pyridine with various boronic acids catalyzed by palladium. In this reaction, vinyl pyridines reacted with various aryl boronic acids in the presence of 10 mol% palladium(II) trifluoroacetate, 10 mol% 1,10- phenanthroline, and 1 equivalent silver(I) oxide, to give the corresponding aryl vinyl pyridine products as a single stereoisomer, with N,N-dimethylformamide as the solvent and under 1 atmosphere of oxygen gas. The aryl vinyl pyridine products were obtained in moderate to good yields after 24 hours. A mechanism for the reaction is proposed.
- Chen, Shanshan,Zhang, Xiuli,Chu, Mingjie,Gan, Xiaoping,Lv, Xianhai,Yu, Jie
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supporting information
p. 791 - 796
(2015/03/30)
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- Heck cross-coupling of vinyl heteroaromatic compounds with aryl and heteroaryl halides using Pd(II) complex under phosphine-free conditions
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The palladium-catalyzed cross-coupling reaction of vinyl heteroaromatic compounds with aryl bromides and heteroaryl bromides is described using air and moisture stable N,N′,N″,O-tetrafunctional Pd catalyst under phosphine-free conditions. As a result a variety of trans-1,2-disubstituted vinyl heterocycles were obtained in high to good yields.
- Annapurna, Manne,Vishnuvardhan Reddy,Singh, Surya Prakash,Kantam, Mannepalli Lakshmi
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p. 10940 - 10945
(2014/01/06)
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- Use of silver carbonate in the Wittig reaction
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An efficient synthesis of olefins by the coupling of stabilized, semistabilized, and nonstabilized phosphorus ylides with various carbonyl compounds in the presence of silver carbonate is reported. Wittig olefination of aromatic, heteroaromatic, and aliphatic aldehydes (yields >63%) and a ketone (yield 42%) are demonstrated. These reactions proceed overnight at room temperature, under weakly basic conditions, and as such extend the applicability of the Wittig reaction to base-sensitive reactants.
- Jedinak, Lukas,Rush, Latoya,Lee, Mijoon,Hesek, Dusan,Fisher, Jed F.,Boggess, Bill,Noll, Bruce C.,Mobashery, Shahriar
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p. 12224 - 12228
(2014/01/06)
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- Synthesis and anti-inflammatory activity of resveratrol analogs
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Seventeen novel resveratrol derivatives were synthesized. Their anti-inflammatory activities were tested on xylene-induced mouse ear edema. The pharmacological results showed that some compounds have potent anti-inflammatory activities.
- Chen, Guoliang,Shan, Wei,Wu, Yingliang,Ren, Lixiang,Dong, Jinhua,Ji, Zhizhong
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p. 1587 - 1590
(2007/10/03)
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- Ruthenium-mediated regio- and stereoselective alkenylation of pyridine
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A novel alkenylation reaction of pyridine is developed. Heating a cationic ruthenium vinylidene complex [CpRu(C=C=HR)(PPh3)2]PF6 in pyridine at 100-125 °C for 24 h affords (E)-2-alkenylpyridine. Initially, pyridine coordinates to ruthenium by displacement of one of the phosphine ligands. Then, [2 + 2] heterocycloaddition occurs to form a four-membered ruthenacyclic complex. Deprotonation of the β-hydrogen affords a neutral π-azaallyl complex. Protonolysis furnishes the product. As a result, a vinylidene group is inserted into the α C-H bond of pyridine. The alkenylation reaction is made catalytic in ruthenium by the use of (alkyn-1-yl)silane as the vinylidene source. Treatment of (alkyn-1-yl)trimethylsilane with pyridine in the presence of a cationic ruthenium complex [CpRu(PPh3)2]PF6 affords the corresponding (E)-2-alkenylpyridine in good yield in a regio- and stereoselective manner. Copyright
- Murakami, Masahiro,Hori, Seiji
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p. 4720 - 4721
(2007/10/03)
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- CHARACTERISTIC FEATURES OF THE CONDENSATION OF PICOLINE BORON TRIFLUORIDE COMPLEXES WITH AROMATIC ALDEHYDES
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The formation of complexes 2- and 4-picolines with BF3 results in a significant activation of their methyl groups.This makes it possible to carry out condensations with aromatic aldehydes under mild conditions.The reaction of 2-picoline with 4-(dimethylamino)benzaldehyde in acetic anhydride solution results in the splitting of the pyridine ring with formation of an unstable product.
- Vasil'ev, A. N.,Mushkalo, L. K.
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p. 1718 - 1720
(2007/10/02)
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- An interesting chloride ion effect in the Heck reaction
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Addition of chloride ion is found to enhance the yields of cross-couplings between aryl iodides and selected olefin acceptors.
- Merlic, Craig A.,Semmelhack, M.F.
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p. C23 - C27
(2007/10/02)
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- Reactions of Lithio Trimethylsilyl Compounds with Nitrones
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The reactions of lithio compounds, generated in situ from 2-pyridine (1), N,N-dimethyl(trimethylsilyl)acetamide (2), and ethyl (trimethylsilyl)acetate (3) and LDA in THF, with various nitrones have been investigated.The lithio compounds of 1-3 reacted with α,N-diarylnitrones to give the corresponding (E)-alkenes together with azoxybenzene and/or azobenzene.On the other hand, the reaction of lithio derivative of 1 with α-aryl-N-alkylnitrones, α,N-dialkylnitrones, and cyclic nitrones afforded the aziridine compounds as the major products, accompanied by hydroxylamine derivatives in some cases.The lithio derivative of 2 or 3 reacted with α,N-dialkylnitrones and cyclic nitrones to give the aziridine and/or isoxazolidinone derivatives.The pathways for the formation of the above products are also described.
- Tsuge, Otohiko,Sone, Kazuhiro,Urano, Satoshi,Matsuda, Koyo
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p. 5171 - 5177
(2007/10/02)
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- REACTIONS OF SILYL-SUBSTITUTED CARBANIONS WITH NITRONES
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The reaction of carbanions, prepared from 2-(trimethylsilylmethyl)pyridine or N,N-dimethyltrimethylsilylacetamide and lithium diisopropylamide in tetrahydrofuran, with α-aryl-N-phenylnitrones afforded a mixture of corresponding (E)-alkene, azobenzene and azoxybenzene, respectively.On the other hand, the carbanions reacted with cyclic nitrones to give the corresponding aziridine and/or hydroxylamine derivatives as major products.
- Tsuge, Otohiko,Sone, Kazuhiro,Urano, Sathoshi
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p. 977 - 980
(2007/10/02)
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