- Construction of highly sterically hindered 1,1-disilylated terminal alkenes
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One direct and efficient procedure for the synthesis of 1,1-disilylated terminal alkenes is demonstrated in this paper. To overcome and rationally utilize the steric hindrance of silyl units, the cationic ruthenium catalyst [CpRu(MeCN)3]+ was found to be effective for Markovnikov hydrosilylation of 1-silyl terminal alkynes with high yields and excellent regioselectivity. Dissimilarities between alkyl and alkoxy silyl units lead to versatile product derivatizations toward a variety of useful building blocks.
- Zhang, Xueyan,Ji, Xin,Xie, Xingze,Ding, Shengtao
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supporting information
p. 12958 - 12961
(2018/11/23)
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- Geometry-Constrained Iminopyridyl Palladium-Catalyzed Hydroarylation of Alkynes to Prepare Tri-substituted Alkenes Using Alcohol as Reductant
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We developed an efficient and straightforward method to prepare tri-substituted alkenes through palladium-catalyzed hydroarylation of alkynes with aryl bromides. Diarylacetylenes and alkyl(aryl)acetylenes could be well hydroarylated with various aryl bromides in moderate to excellent yields. Mechanistic studies suggested that alcohol was the reductant to provide hydride through β-H elimination. Gram scale reaction further demonstrated the practicality and efficiency of the newly developed strategy. (Figure presented.).
- Wu, Ke,Sun, Nan,Hu, Baoxiang,Shen, Zhenlu,Jin, Liqun,Hu, Xinquan
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supporting information
p. 3038 - 3043
(2018/08/01)
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- Reagent for enhancing generation of chemical species
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A reagent that enhances acid generation of a photoacid generator and composition containing such reagent is disclosed. Described is a reagent that generates a first chemical species in at least one of a composition including the reagent, a solution of the composition, and a film formed of the composition. Further described is a reagent that generates a first product in at least one of a composition including the reagent, a solution of the composition, and a film formed of the composition.
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Page/Page column 13
(2016/11/24)
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- REAGENT FOR ENHANCING GENERATION OF CHEMICAL SPECIES
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A reagent that enhances acid generation of a photoacid generator and composition containing such reagent is disclosed.
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Paragraph 0039
(2016/06/13)
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- CHEMICAL SPECIES GENERATION IMPROVEMENT REAGENT
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PROBLEM TO BE SOLVED: To provide a reagent that improves acid generation from a photoacid generator in chemically amplified resist. SOLUTION: This invention provides 1,1,2-tris (4-methoxyphenyl)-2-triethylsilylethane. The compound releases electrons by light irradiation to promote acid generation from a photoacid generator, and is converted to a phenanthrene derivative by photochemical intramolecular cyclization reaction of a product to further promote acid generation as a sensitizer. COPYRIGHT: (C)2015,JPOandINPIT
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Paragraph 0109; 0110; 0111
(2016/12/12)
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- Unexpected and powerful effect of chlorobenzene in direct palladium-catalyzed cascade Sonogashira-hydroarylation reaction
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A ubiquitous accelerating effect of chlorobenzene (PhCl) was observed unexpectedly in the Pd-catalyzed cascade Sonogashira-hydroarylation reaction. This new type of carbon-carbon bond forming cross-coupling reaction was efficiently catalysed by Pd2(dba)3 in the presence of a catalytic amount of PhCl, which provides a facile and direct approach to the synthesis of trisubstituted olefins.
- Yu, Bo,Xu, Wei,Sun, Huaming,Yu, Binxun,Zhang, Guofang,Xu, Li-Wen,Zhang, Weiqiang,Gao, Ziwei
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p. 8351 - 8354
(2015/02/19)
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- Controlled mono- and double-Heck reaction catalyzed by a dicarbene dipalladium complex
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The phosphine-free mono- and double-Heck reaction of terminal olefins with electron-deficient and electron-rich aryl halides (iodides and bromides) is described. These reactions are catalyzed by the dicarbene dipalladium complex 1 by controlling the stoichiometry of the aryl halide and the olefine, the loading of the palladium catalyst, as well as using different base, and with or without additive. The procedure of double-Heck reaction allows β,β- diarylation and β,β′-diarylation of terminal olefins and affords trisubstituted olefins in good to excellent yields.
- Li, Yunfei,Liu, Gang,Cao, Changsheng,Wang, Shuzhan,Li, Yuling,Pang, Guangsheng,Shi, Yanhui
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p. 6241 - 6250
(2013/07/27)
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- Solid supported palladium(0) nano/microparticle: A ligand-free efficient recyclable heterogeneous catalyst for mono- and β,β-double-Heck reaction
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Solid supported palladium nano/microparticles were found to be active catalysts to perform mono- and β,β-double-Heck reactions. Different β-unsubstituted and substituted alkenes including acrylate, methacrylate, crotonate, styrene, acrylonitrile, and acrylamide were investigated successfully for mono- and β,β-double-Heck reactions with aryl iodide under milder reaction condition. One-pot β,β-double-Heck reaction of aryl iodides with α,β-unsaturated ester, amide, nitrile, and styrene derivatives were also performed under standard reaction conditions. Wide functional group tolerance, easy catalyst recovery, and recyclability up to twelve times without significant loss of catalytic activity added extra importance to the present process.
- Sharma, Dharminder,Kumar, Sandeep,Shil, Arun K.,Guha, Nitul Ranjan,Bandna,Das, Pralay
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supporting information
p. 7044 - 7051
(2013/01/15)
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- Palladium-catalyzed double arylations of terminal olefins in acetic acid
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A palladium-catalyzed Heck diarylation of terminal olefins under ligand-free conditions in acetic acid is described. This procedure allows double arylation of terminal olefins affording trisubstituted olefins in good to excellent yields. The methodology is applicable to the coupling of both electron-deficient and electron-rich aryl iodides leading to symmetrical and unsymmetrical β,β-diarylated alkenes.
- Xu, Daichao,Lu, Chunxin,Chen, Wanzhi
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experimental part
p. 1466 - 1474
(2012/03/08)
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- Exploratory studies on the reaction between iodoarenes and acetylenes: One-pot, Pd-[Bmim][BF4] catalyzed preparation of trianisylethylene
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The reaction between iodoarenes and acetylenes mediated by palladium was studied, showing selectivity changes based on the nature of the substituent. A new, phosphine-, copper-, and amine-free methodology was developed, in which the synthesis of trianisylethylene from 4-iodoanisole and trimethylsilylacetylene was promoted presumably by an N-heterocyclic-carbene derived from an ionic liquid and a palladium salt, using ethanol as the hydrogen source. Graphical Abstract: [Figure not available: see fulltext.]
- Barros, Jose C.,Souza, Andrea L. F.,Da Silva, Joaquim F. M.,Antunes
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scheme or table
p. 549 - 553
(2012/01/13)
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- Antiestrogenically active 1,1,2-tris(4-hydroxyphenyl)alkenes without basic side chain: Synthesis and biological activity
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C2-Alkyl substituted derivatives of the 1,1,2-tris(4-hydroxyphenyl)ethene 3a (alkyl = Me (3b), Et (3c), Prop (3d), But (3e)) were synthesized by reaction of 1,2-bis(4-methoxyphenyl)ethanone with the appropriate alkyl halide, followed by a Grignard reaction with 4-methoxyphenylmagnesium bromide, dehydration with phosphoric acid or hydrobromic acid, and ether cleavage with BBr3. The compounds were tested for estrogen receptor (ER) binding affinity in a competition experiment with radio labeled estradiol ([3H]-E2) and for gene activation on the ER-positive MCF-7-2a cell line. All compounds showed high receptor binding affinity (RBA-value: 3b (52. 1%) > 3a (45.5%) > 3c (29.6%) > 3d (4.03%) > 3e (0.95%)). The tests on hormone dependent MCF-7-2a breast cancer cells, stably transfected with the plasmid EREwtcluc, revealed that all 1,1,2-tris(4-hydroxyphenyl)ethenes antagonized the effect of 1 nM estradiol (E2). The compounds 3b (IC50 = 15 nM) and 3c (IC50 = 10 nM) were equal in their effects to 4-hydroxytamoxifen (4OHT) (IC50 = 7 nM). Agonistic effects were low. Only 3a and 3b activated the luciferase expression (relative activation at 1 μM: 3a 60%; 3b 35%). Despite their highly antagonistic potency, the 1,1,2-tris(4-hydroxyphenyl)ethenes showed only low cytotoxic properties on the hormone sensitive MCF-7 cell line.
- Lubczyk, Veronika,Bachmann, Helmut,Gust, Ronald
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p. 1484 - 1491
(2007/10/03)
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- Palladium-catalyzed reactions of aryl iodides with trimethylsilylacetylenes and disubstituted alkynes: The synthesis of diarylacetylenes and triarylethylenes
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Treatment of 2.5 equiv. of aryl iodide with trimethylsilylacetylene in the presence of 3 equiv. of sodium methoxide and 5 mol% of Pd(PPh3)4 under refluxing methanol for 6 h gave diarylacetylene in good chemical yields. When the catalyst was replaced by Pd(dba)2 and 5 equiv. of aryl iodide were added under the same reaction conditions, triarylethylenes were obtained in 70-85% yields. Only the sterically hindered o-methoxyiodobenzene and 2-iodothiophene gave the diarylacetylene, but also in good chemical yield. Reaction of aryl iodides with disubstituted alkynes in the presence of Pd(OAc)2 and sodium methoxide in methanol produced trisubstituted ethylenes in modest to good yields. The hydrogenolysis of the organopalladium is proposed through β-hydride elimination of the palladium methanolate intermediates.
- Wu, Ming-Jung,Wei, Li-Mei,Lin, Chi-Fong,Leou, Shiow-Piaw,Wei, Li-Lan
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p. 7839 - 7844
(2007/10/03)
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- Triarylcyclopropanes as antiestrogens and antitumor agents
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Triarylcyclopropane derivatives in which one or more of the aryl groups includes a hydroxy as a substituted or unsubstituted or alkoxy or side chain substituent. The compounds are useful as antiestrogens and anti-tumor agents.
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- Photoreactivity of Some α-Arylvinyl Bromides in Acetic Acid. Selectivity toward Bromide versus Acetate Ions as a Mechanistic Probe
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The photochemical reactions of four α-anisyl-β,β-diarylvinyl bromides (1a-1d), three α-phenyl-β,β-diarylvinyl bromides (1e-1g), and 9-(α-bromo-p-methoxybenzylidene)anthrone (2) in acetic acid in the presence of sodium acetate and tetraethylammonium bromide (labeled with 82Br) have been studied quantitatively. Bromide exchange, acetate formation, E/Z isomerization, an anisyl 1,2-shift, stilbene-type cyclization to phenanthrenes, reductive debromination, and oxidation are observed as primary pathways. For all compounds 1, nucleophilic substitution, accompanied by E/Z isomerization in both starting material and product with 1b,c and 1f,g and an anisyl 1,2-shift in 1e but not in 1f,g, is quite efficient and by far the most important process. (Quantum yields range from 0.1 to 0.3 as compared to 0.01-0.02 for cyclization and 0.001-0.01 for reduction). The α-anisylvinyl bromide 2 is virtually inert for photosubstitution. The selectivity constants toward bromide and acetate ions, corrected for their temperature dependence, the amounts of E/Z isomerized starting material and product, the occurrence or nonoccurrence of an anisyl 1,2-shift, and the nature of the capturing nucleophile in the acetolysis are all in quantitative agreement with the corresponding data for the thermal reactions of 1 in the same medium. The results strongly support a mechanism for the nucleophilic vinylic photosubstitution reactions that involves the generation of a product-forming intermediate, which is exactly the same as the intermediate formed in the thermal reaction, a "cold" (thermally relaxed) linear free vinyl cation.
- Van Ginkel, Frits I. M.,Cornelisse, Jan,Lodder, Gerrit
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p. 4261 - 4272
(2007/10/02)
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- Lithium aluminium hydride reduction of some triarylvinyl bromides and acetates catalyzed by some transition metal chlorides
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A number of triarylvinyl halides and acetates were reduced with lithium aluminium hydride using various transition metal chlorides as catalysts.The vinylic halides were reduced to the corresponding alkenes while the vinylic acetates were reduced to mixtures of triarylketones and alcohols.The reduction of labeled vinylic halides did not result in any scrambling of the label from C-2 to C-1.The reactions took place under mild conditions and relativley fast reaction times.
- Obafemi, Craig A.,Lee, Choi Chuck
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p. 1998 - 2000
(2007/10/02)
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- AMINIUM RADICAL SALT CATALYZED DESULPHURIZATION OF THIIRANES: AN EFFICIENT PREPARATION OF ARYLSUBSTITUTED OLEFINS
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Arylsubstituted olefins are obtained from corresponding thiiranes in high yields under mild conditions by using catalytic amount of tris-(p-bromophenyl)aminium hexachloroantimonate (1) as a single electron transfer (SET) oxidant.
- Kamata, Masaki,Murayama, Kazuyuki,Miyashi, Tsutomu
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p. 4129 - 4132
(2007/10/02)
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- FROM THIIRANES TO THIOCARBONYL S-SULFIDES; RECENT RESULTS
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A novel nucleophilic catalysis for the desulfurization of thiiranes is described.Triphenylthiirane is quantitatively converted to triphenylethylene by some molpercent sodium thiophenoxide or other thiolates in DMSO at 35 deg C.A rapid initial reaction is retarded by the eliminated sulfur leading to a pseudo-first-order reaction under quasi-stationary conditions.The suggested mechanism is based on structure-rate relationships. - The thiolate-catalyzed reaction of cis-2,3-diphenylthiirane is exceptional in furnishing equimolar quantities of cis-stilbene and 3,4,6,7-tetraphenyl-1,2,5-trithiepane (2 diastereoisomers with bilateral symmetry); mechanistic implications - thiolate attack on sulfur or C-atom of thiirane - are discussed. - Desulfurization of 2,2-diphenylthiirane by thiobenzophenone or other thioketones gives access to thiocarbonyl S-sulfides ("thiosulfines") which are intercepted by 1,3-cycloadditions to activated acetylenes or to thiones.
- Huisgen, Rolf
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- Photochemistry of Vinyl Halides. Heterocycles from Reaction of Photogenerated Vinyl Cations with Azide Anion
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Irradiation of 1,2,2-tris(p-methoxyphenyl)vinyl bromide (1a-Br) and tetrabutylammonium azide in acetonitrile afforded 1,1,3,4,6,6-hexakis(p-methoxyphenyl)-2,5-diaza-1,3,5-hexatriene (2a).Formation of 2a suggests the presence of azirine 3a as a reactive intermediate and a route to synthesis of heterocycles in combination with azirine photochemistry.Irradiation of α-arylvinyl halides 1 and tetrabutylammonium azide in acetonitrile in the presence of dimethyl fumarate gave 1-pyrrolidine derivatives 5.When the irradiation was performed in acetone, oxazoline derivatives 6 were obtained.The reaction of vinyl halides 1 with azide anion took place succesfully even in a two phase system, i.e., water-methylene chloride-tetrabutylammonium halide as a phase-transfer catalyst.In addition, photolysis of 2,2-bis(p-methoxyphenyl)-1-phenylvinyl bromide (1f-Br) in a two-phase system led to the formation of the β-aryl rearranged pyrrolines 5f.This results indicates strong evidence for the intervention of vinyl cations in the photochemical reaction of the vinyl halide 1 and azide anion.The mechanistic points on the photochemical substitution and the scope and limitation of the reaction are discussed.
- Kitamura, Tsugio,Kobayashi, Shinjiro,Taniguchi, Hiroshi
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p. 4755 - 4760
(2007/10/02)
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