1725-76-4Relevant academic research and scientific papers
Piperidine-appended imidazolium ionic liquid as task-specific basic-IL for Suzuki and Heck reactions and for tandem Wittig-Suzuki, Wittig-Heck, Horner-Emmons-Suzuki, and Horner-Emmons-Heck protocols
Savanur, Hemantkumar M.,Kalkhambkar, Rajesh G.,Laali, Kenneth K.
, p. 150 - 161 (2017/06/30)
Facile, high yielding, one-pot methods for the synthesis of a library of diversely substituted bi-aryls, diarylethenes, and aryl-enoates, via Suzuki and Heck reactions, and by sequential Wittig-Suzuki, Wittig-Heck, Horner-Emmons-Suzuki, and Horner-Emmons-Heck reactions are reported. The reactions employ piperidine-appended imidazolium ionic liquid [PAIM][NTf2] as a task-specific basic-IL, butyl-methyl-imidazolium ionic liquid [BMIM][X] (X?=?PF6, BF4) as solvent, and catalytic amounts of Pd(OAc)2 with no other additives. Wittig and Horner-Emmons reactions are effected by reacting substituted benzaldehydes with 4-bromobenzyl-PPh3 (or bromomethyl-PPh3) phosphonium salts, or diethylphosphonate with bromobenzaldehydes respectively, to form the corresponding ethenes. Subsequent cross-coupling reactions are accomplished by addition of aryl-boronic acid or phenyl-ethenes along with Pd(OAc)2 to bring about the aforementioned hyphenated transformations. The feasibility to perform double-olefination via Wittig and Horner-Emmons reactions with dialdehydes to form highly conjugated bis-styryl and bis-enoate compounds is also shown. The [BMIM][X] solvent is recycled and reused.
High Loading of Pd Nanoparticles by Interior Functionalization of MOFs for Heterogeneous Catalysis
Gole, Bappaditya,Sanyal, Udishnu,Banerjee, Rahul,Mukherjee, Partha Sarathi
, p. 2345 - 2354 (2016/03/19)
In this report, the issue related to nanoparticle (NP) agglomeration upon increasing their loading amount into metal-organic frameworks (MOFs) has been addressed by functionalization of MOFs with alkyne groups. The alkynophilicity of the Pd2+ (or other noble metals) ions has been utilized successfully for significant loading of Pd NPs into alkyne functionalized MOFs. It has been shown here that the size and loading amount of Pd NPs are highly dependent on the surface area and pore width of the MOFs. The loading amount of Pd NPs was increased monotonically without altering their size distribution on a particular MOF. Importantly, the distinct role of alkyne groups for Pd2+ stabilization has also been demonstrated by performing a control experiment considering a MOF without an alkyne moiety. The preparation of NPs involved two distinct steps viz. adsorption of metal ions inside MOFs and reduction of metal ions. Both of these steps were monitored by microscopic techniques. This report also demonstrates the applicability of Pd@MOF NPs as extremely efficient heterogeneous catalysts for Heck-coupling and hydrogenation reactions of aryl bromides or iodides and alkenes, respectively.
Small molecules that protect against β-amyloid-induced cytotoxicity by inhibiting aggregation of β-amyloid
Lee, Yun Suk,Kim, Hye Yun,Kim, Youngsoo,Seo, Jae Hong,Roh, Eun Joo,Han, Hogyu,Shin, Kye Jung
, p. 4921 - 4935 (2012/10/08)
Aggregated β-amyloid (Aβ) plays crucial roles in Alzheimer's disease (AD) pathogenesis, therefore blockade of Aβ aggregation is considered as a potential therapeutic target. We designed and synthesized small molecules to reduce Aβ-induced cytotoxicity by inhibiting Aβ aggregation. The small molecules were screened via ThT, MTT, and cell-based cytotoxicity assay (Aβ burden assay). Selected compounds 1c, 1d, 1e, and 1f were then investigated by evaluating their effects on cognitive impairment of acute AD mice model. Learning and memory dysfunction by injection of Aβ(1-42) was recovered by administration of these molecules. Especially, 1d showed the best recovery activity in Y-maze task, object recognition task, and passive avoidance task with dose dependent manner. These results suggest that 1d has high potential as a therapeutic agent for AD.
Rhodium-catalyzed regioselective olefination directed by a carboxylic group
Mochida, Satoshi,Hirano, Koji,Satoh, Tetsuya,Miura, Masahiro
scheme or table, p. 3024 - 3033 (2011/06/24)
The ortho-olefination of benzoic acids can be achieved effectively through rhodium-catalyzed oxidative coupling with alkenes. The carboxylic group is readily removable to allow ortho-olefination/decarboxylation in one pot. α,β-Unsaturated carboxylic acids
Synthesis of stilbene and distyrylbenzene derivatives through rhodium-catalyzed ortho -olefination and decarboxylation of benzoic acids
Mochida, Satoshi,Hirano, Koji,Satoh, Tetsuya,Miura, Masahiro
, p. 5776 - 5779 (2011/03/18)
Ortho-substituted benzoic acids efficiently undergo precisely ordered ortho-olefination/decarboxylation upon treatment with styrenes in the presence of a rhodium catalyst and silver salt oxidant to afford the corresponding meta-substituted stilbene deriva
Aminophosphine palladium pincer complexes for Suzuki and Heck reactions
Bolliger, Jeanne L.,Frech, Christian M.
scheme or table, p. 23 - 28 (2010/04/24)
The aminophosphine-based pincer complexes [C6H 3-2,6-{NHP(piperidinyl)2}2Pd(CI)] (2) and [C6H3-2,6-{OP(piperidinyl)2}2Pd(CI)] (3) are readily prepared from cheap starting materials by sequential addition of 1,1′,1 "-phosphinetriyltripiperidine and 1,3-diaminobenzene or resorcinol to solutions of [Pd(cod)(CI)2] (cod = cyclooctadiene) in toluene under N2 in 'one pot'. Compounds 2 and 3 proved to be not only excellent catalysts for the Suzuki and the Heck cross-coupling reactions, but they are also very convenient to use: The toluene solutions of the 'one-pot' syntheses can be used directly for the catalytic reactions, thereby saving the time-consuming isolation of the catalysts. The Suzuki cross-coupling reaction catalyzed by 2 and 3 can be performed in air at 100 °C in toluene of technical quality: in the presence of only 0.001 mol% of catalyst, several electronically deactivated and sterically hindered aryl bromides are quantitatively coupled with phenylboronic acid within a few minutes of reaction time. Furthermore, complex 2 enables the use of activated and non-activated aryl chlorides as coupling partners in the Suzuki reaction. Compounds 2 and 3 have also been shown to be highly active and reliable Heck catalysts: Very low catalyst loadings and short reaction times are required for the quantitative coupling of several electronically deactivated and sterically hindered aryl bromides with various olefins at 140 °C. At increased temperatures, even electronically deactivated and sterically hindered aryl chlorides can be efficiently coupled with olefins in the presence of only 0.01 mol% of catalyst. Schweizerische Chemische Gesellschaft.
Rationally designed pincer-type heck catalysts bearing aminophosphine substituents: PdIV intermediates and palladium nanoparticles
Bolliger, Jeanne L.,Blacque, Olivier,Frech, Christian M.
experimental part, p. 7969 - 7977 (2009/09/08)
The aminophosphine-based pincer complexes [C6H 3-2,6-{XP(piperidinyl)2}2Pd(Cl)] (X = NH 1; X = O 2) are readily prepared from cheap starting materials by sequential addition of 1,1′,1″-phosphinetriyltripiperidine and 1,3-diaminobenzene or resorcinol to solutions of [Pd(cod)(Cl)2] (cod = cyclooctadiene) in toluene under N2 in "one pot". Compounds 1 and 2 proved to be excellent Heck catalysts and allow the quantitative coupling of several electronically deactivated and sterically hindered aryl bromides with various olefins as coupling partners at 140°C within very short reaction times and low catalyst loadings. Increased reaction temperatures also enable the efficient coupling of olefins with electronically deactivated and sterically hindered aryl chlorides in the presence of only 0.01 mol% of catalyst. The mechanistic studies performed rule out that homogeneous Pd0 complexes are the catalytically active forms of 1 and 2. On the other hand, the involvement of palladium nanoparticles in the catalytic cycle received strong experimental support. Even though pincer-type PdIV intermediates derived from 1 (and 2) are not involved in the catalytic cycle of the Heck reaction, their general existence as reactive intermediates (for example, in other reactions) cannot be excluded. On the contrary, they were shown to be thermally accessible. Compounds 1 and 2 show a smooth halide exchange with bromobenzene to yield their bromo derivatives in DMF at 100°C. Experimental observations revealed that the halide exchange most probably proceeded via pincer-type PdIV intermediates. DFT calculations support this hypothesis and indicated that aminophosphine-based pincer-type PdIV intermediates are generally to be considered as reactive intermediates in reactions with aryl halides performed at elevated temperatures.
Palladium-Imidazolium Carbene Catalyzed Mizoroki-Heck Coupling with Aryl Diazonium Ions
Andrus, Merritt B.,Song, Chun,Zhang, Jiuqing
, p. 2079 - 2082 (2007/10/03)
(Matrix Presented) Catalyst formed from N,N-bis(2,6-diisopropylphenyl)dihydroimidazolium chloride and palladium(II) acetate (2 mol %) was used, without added base, to efficiently produce Heck coupled products with olefins and aryl diazonium tetrafluoroborate substrates. The reactions were performed at room temperature, giving product in 2-4 h with 80-90% yields for isolated materials. Diazonium ions, formed in situ directly from anilines, also couple under these conditions.
Reaction of m-Phenylenebisdiazonium Salts with Unsaturated Compounds
Obushak,Ganushchak,Lesyuk,Pil'o,Demchuk,Mazyar
, p. 432 - 435 (2007/10/03)
Main route of the reaction between m-phenylenebisdiazonium tetrafluoroborate with unsaturated compounds (acrylonitrile, styrene, alkyl acrylates and methacrylates) in the presence of NaCl and a catalyst (CuCl2) is the Meerwein chloroarylation by one diazogroup; the second diazogroup is replaced by chlorine according to Sandmayer's reaction.
Photochemistry of Electron-Rich 1,3-Distyrylbenzenes
Noller, Klaus,Kosteyn, Frank,Meier, Herbert
, p. 1609 - 1616 (2007/10/02)
The 1,3-distyrylbenzenes 3, containing up to seven alkoxy groups, are subjected to the oxidative photocyclization.Elimination of methanol (3bb -> 7bb, 3bf -> 7bf) and quinone oxidation can occur as competitive or consecutive reactions in the formation of the products 6, 7, and 8.Selfsensitized generation of singlet oxygen by 6bf can lead to endoperoxide formation (6bf -> 11).
