- First Heck reaction with arenediazonium cations with recovery of Pd-triolefinic macrocyclic catalyst
-
(Matrix presented) The air- and moisture-stable phosphine-free palladium(0) complex 1 is a highly active and recoverable catalyst for Heck olefination of aryl diazonium tetrafluoroborates. The reactions were performed under aerobic conditions at room temperature to give the coupling products in excellent yields.
- Masllorens, Judit,Moreno-Manas, Marcial,Pla-Quintana, Anna,Roglans, Anna
-
-
Read Online
- N-Heterocyclic carbene palladium (II)-pyridine (NHC-Pd (II)-Py) complex catalyzed heck reactions
-
A mild, efficient, and practical catalytic system for the synthesis of highly privileged stilbene pharmacophores is reported. This system uses N-heterocyclic carbene palladium (II) Pyridine (NHC-Pd (II)-Py) complex to catalyze the formation of carbon-carbon bonds between olefin derivatives and various bromide. This simple, gentle and user-friendly method can offer a variety of stilbene products in excellent yields under solvent-free condition. And its scale-up reaction has excellent yield and this system can be applied to industrial fields. The utility of this method is highlighted by its universality and modular synthesis of a series of bioactive molecules or important medical intermediates.
- Li, Dan,Tian, Qingqiang,Wang, Xuetong,Wang, Qiang,Wang, Yin,Liao, Siwei,Xu, Ping,Huang, Xin,Yuan, Jianyong
-
supporting information
p. 2041 - 2052
(2021/05/25)
-
- A Bis (BICAAC) Palladium(II) Complex: Synthesis and Implementation as Catalyst in Heck-Mizoroki and Suzuki-Miyaura Cross Coupling Reactions
-
Carbenes are one of the most appealing, well-explored, and exciting ligands in modern chemistry due to their tunable stereoelectronic properties and a wide area of applications. A palladium complex (BICAAC)2PdCl2 with a recently discovered cyclic (alkyl)(amino)carbene having bicyclo[2.2.2] octane skeleton (BICAAC) was synthesized and characterized. The enhanced σ-donating and π-accepting ability of this carbene lend a hand to form a robust Pd-carbene bond, which allowed us to probe its reactivity as a precatalyst in Heck-Mizoroki and Suzuki-Miyaura cross-coupling reactions with low catalyst loading in open-air conditions. The diverse range of substrates was explored for both the cross-coupling reactions. To get a better understanding of the catalytic reactions, several analytical techniques such as field-emission scanning electron microscopy, high-resolution transmission electron microscopy, and powder X-ray diffraction were employed in a conclusive manner.
- Chakrabortty, Soumyadeep,Kaur, Mandeep,Adhikari, Manu,Manar, Krishna K.,Singh, Sanjay
-
supporting information
p. 6209 - 6217
(2021/05/06)
-
- Palladium-Based Catalysts Supported by Unsymmetrical XYC–1 Type Pincer Ligands: C5 Arylation of Imidazoles and Synthesis of Octinoxate Utilizing the Mizoroki–Heck Reaction
-
A series of new unsymmetrical (XYC–1 type) palladacycles (C1–C4) were designed and synthesized with simple anchoring ligands L1–4H (L1H = 2-((2-(4-methoxybenzylidene)-1-phenylhydrazinyl)methyl)pyridine, L2H = N,N-dimethyl-4-((2-phenyl-2-(pyridin-2-ylmethyl)hydrazono)methyl)aniline, L3H = N,N-diethyl-4-((2-phenyl-2-(pyridin-2-ylmethyl)hydrazono)methyl) aniline and L4H = 4-(4-((2-phenyl-2-(pyridin-2-ylmethyl)hydrazono) methyl)phenyl)morpholine H = dissociable proton). Molecular structure of catalysts (C1–C4) were further established by single X-ray crystallographic studies. The catalytic performance of palladacycles (C1–C4) was explored with the direct Csp2–H arylation of imidazoles with aryl halide derivatives. These palladacycles were also applied for investigating of Mizoroki–Heck reactions with aryl halides and acrylate derivatives. During catalytic cycle in situ generated Pd(0) nanoparticles were characterized by XPS, SEM and TEM analysis and possible reaction pathways were proposed. The catalyst was employed as a pre-catalyst for the gram-scale synthesis of octinoxate, which is utilized as a UV-B sunscreen agent.
- Maji, Ankur,Singh, Ovender,Singh, Sain,Mohanty, Aurobinda,Maji, Pradip K.,Ghosh, Kaushik
-
p. 1596 - 1611
(2020/04/29)
-
- An efficient palladium catalyzed Mizoroki-Heck cross-coupling in water
-
The homogeneous Pd-catalysed Mizoroki-Heck coupling reaction was successfully performed in water in the absence of any additives under aerobic conditions. The various key reaction parameters that affect the yield of the desired cross-coupling product were optimized. The Pd(PPh3)4/Et3N/H2O/98 °C catalyst system was found to be highly active (TOF = 12 to 14 h-1) towards achieving excellent yield of the Mizoroki-Heck coupling products for a wide range of electron-withdrawing as well as electron-donating aryl bromides and chlorides in the shortest reaction time. Pd(PPh3)4 catalyst deactivation during the Mizoroki-Heck coupling reaction was investigated and to evolve a strategy for achieving ten times Pd-metal recyclability without appreciable loss of its activity. Thus, the proposed mechanism provides access to a variety of olefins in aqueous medium, making this protocol eco-friendly.
- Jadhav, Sanjay N.,Rode, Chandrashekhar V.
-
supporting information
p. 5958 - 5970
(2017/12/26)
-
- Cyclodextrin-Grafted Silica-Supported Pd Nanoparticles: An Efficient and Versatile Catalyst for Ligand-Free C-C Coupling and Hydrogenation
-
Silica is an extremely versatile support, which is capable of hosting metal nanoparticles (NPs) and enhancing their stability and reactivity. In this study, a novel cyclodextrin/silica support for Pd NPs, which we have denoted Pd/Si-CD, has been prepared. The highly efficient and homogeneous impregnation of small palladium nanoparticles on this support has been carried out under conventional conditions, and ultrasound irradiation has been shown to have a beneficial effect on catalyst preparation. The catalyst exhibited excellent activity in ligand-free C-C Suzuki and Heck couplings with a large number of aryl iodide and bromides, in which microwave irradiation use cuts down reaction time. Pd/Si-CD have shown high activity and selectivity in the hydrogenation reaction, and the semihydrogenation of phenyl acetylene was also studied with excellent results.
- Martina, Katia,Baricco, Francesca,Caporaso, Marina,Berlier, Gloria,Cravotto, Giancarlo
-
p. 1176 - 1184
(2016/04/05)
-
- A chiral ligand mediated aza-conjugate addition strategy for the enantioselective synthesis of β-amino esters that contain hydrogenolytically sensitive functionality
-
Aza-conjugate addition of the lithium anion of N-trimethylsilyl-p-methoxybenzylamine to tert-butyl enoate acceptors, in the presence of a stoichiometric amount of enantiopure 1,2-dimethoxy-1,2-diphenylethane and excess trimethylsilyl chloride, affords ter
- Archer, Robert M.,Hutchby, Marc,Winn, Caroline L.,Fossey, John S.,Bull, Steven D.
-
p. 8838 - 8847
(2015/10/20)
-
- A simple catalytic system based on PdCl2(CH3CN) 2 in water for cross-coupling reactions using diazonium salts
-
Aryl-heteroaryl and heteroaryl-heteroaryl compounds are obtained through the Suzuki-Miyaura cross-coupling reactions between diazonium salts and potassium trifluoroborates using PdCl2(CH3CN)2 as the catalyst in water and in the absence of any additive, ligand or base. In addition, the same mild catalytic system is effective for the Matsuda-Heck reaction between several monoolefins with aryldiazonium salts.
- El Bakouri, Ouissam,Fernández, Martí,Brun, Sandra,Pla-Quintana, Anna,Roglans, Anna
-
p. 9761 - 9765
(2013/10/22)
-
- Monomeric Pd(II) complexes with trans-chelated pyrazole ligands as effective pre-catalysts for Heck cross-coupling reaction under mild aerobic conditions
-
A new family of mononuclear palladium(II) complexes with bidentate trans-chelating pyrazole ligands [PdCl2(LR)] (R = H, 1; Et, 2; Ph, 3; CHPh2, 4), where new ligand LEt = 2-ethyl-1,3-bis-(3,5-dimethyl-pyrazol-1-
- Chou, Chang-Chuan,Yang, Chia-Chi,Syu, Hong-Bin,Kuo, Ting-Shen
-
p. 387 - 392
(2013/10/01)
-
- Heck-Matsuda reactions catalyzed by a hydroxyalkyl-functionalized NHC and palladium acetate
-
The functionalized NHC obtained from salt 2 is a good ligand for palladium in the Heck-Matsuda reaction of arenediazonium salts and different alkenes. The reaction is performed with low catalyst loading (0.5-1 mol-% of Pd) and in the absence of a base for acrylates. The protocol is also useful for the preparation of cinnamide derivatives. Compound U-77863 has been prepared successfully in good isolated yield. Cyclohexene was found to be an appropriate substrate for the reaction, giving the corresponding 1-arylcyclohexene as a single regioisomer under the studied reaction conditions. The optimal parameters of the reaction were studied by employing a design of experiments approach. Thus, the use of a small set of reactions allows the trends of the different factors to be studied. This study revealed that the best catalytic system is formed by combination of Pd(OAc)2 and salt 2 in a 1:2 ratio. This catalytic system produces better results without the use of a base. Copyright
- Penafiel, Itziar,Pastor, Isidro M.,Yus, Miguel
-
supporting information; experimental part
p. 3151 - 3156
(2012/07/03)
-
- Synthesis and ring openings of cinnamate-derived N-unfunctionalised aziridines
-
Tert-Butyl cinnamates are aziridinated with high trans-selectivity by an N-N ylide generated in situ from N-methylmorpholine and O-diphenylphosphinyl hydroxylamine. The resulting N-unfunctionalised aziridines are shown to be versatile synthetic building b
- Armstrong, Alan,Ferguson, Alexandra
-
supporting information
p. 1747 - 1752,6
(2020/09/16)
-
- Catalytic application of dinuclear palladium(II) bis(thiosemicarbazone) complex in the Mizoroki-Heck reaction
-
A convenient synthesis of new square planar dinuclear palladium(II) terephthaldehyde bis(thiosemicarbazone) complex has been described. The compositions of the complex have been established by elemental analysis, spectral methods and single crystal X-ray crystallographic technique. The new complex acts as an active recyclable homogeneous catalyst for the Mizoroki-Heck reaction of electron deficient (activating) and electron rich (deactivating) aryl halides with various olefins under optimized conditions.
- Prabhu, Rupesh Narayana,Ramesh, Rengan
-
supporting information
p. 5961 - 5965,5
(2020/08/20)
-
- Mizoroki-Heck and Sonogashira cross-couplings catalyzed by CNC palladium pincer complexes in organic and aqueous media
-
The catalytic activity of two CNC palladium pincer complexes is evaluated in two fundamental C - C bond-forming reactions: Mizoroki - Heck and Sonogashira cross-couplings. After several optimization attempts and a brief comparison with a PCN pincer cataly
- SanMartin, Raul,Ines, Blanca,Moure, Maria Jesus,Herrero, Maria Teresa,Dominguez, Esther
-
experimental part
p. 955 - 962
(2012/08/08)
-
- 1,2,3-Triazol-5-ylidene-palladium complex catalyzed Mizoroki-Heck and Sonogashira coupling reactions
-
The bis-1,4-dimesityl-1,2,3-triazol-5-ylidene-palladium complex (1a) successfully catalyzes the Mizoroki-Heck and Sonogashira coupling reactions with aryl bromides to give the corresponding alkenes and alkynes, respectively, in good to excellent yields. In the Mizoroki-Heck reaction, electron-rich, electron-poor, and functionalized aryl bromides and alkenes are tolerated, while the substrates are limited to electron-poor aryl halides in the Sonogashira coupling reaction. The palladium complex also catalyzes cross-coupling reactions with aryl chlorides to give higher yields of products than does the bis-IMes-Pd complex analogue (2), under specific conditions.
- Inomata, Sayuri,Hiroki, Hidekatsu,Terashima, Takahiro,Ogata, Kenichi,Fukuzawa, Shin-Ichi
-
experimental part
p. 7263 - 7267
(2011/10/08)
-
- Water-promoted palladium-catalysed Heck cross-coupling reactions of aryl halides with alkenes in TBAB
-
Water was found to promote the ligand-free Pd(OAc)2-catalysed Heck cross-coupling reaction. In the presence of 3 mol% Pd(OAc)2, 2 equiv. of Cs2CO3 and 15 mg of water, the coupling of a wide variety of aryl halides with alkenes proceeded smoothly in TBAB (n-Bu 4NBr) in moderate to excellent yield. The Pd(OAc)2/TBAB system could be recovered and reused at least three times without loss of catalytic activity.
- Tao, Li-Ming,Li, Qiang-Guo,Liu, Wen-Qi,Zhou, Yun,Zhou, Ju-Feng
-
experimental part
p. 154 - 156
(2011/07/07)
-
- An efficient and reusable PdCl2/TBAF system for the Heck reaction under ligand- and solvent-free conditions
-
PdCl2 combined with TBAF (n-Bu4NF) were found to be efficient conditions for the Heck reactions. In the presence of PdCl2 and TBAF, a variety of aryl halides were coupled with alkenes smoothly in moderate to good yields. Moreover, the PdCl2/TBAF system could be recovered and reused several times in the reaction. Note that these reactions are conducted under solvent-free, ligand-free and reusable conditions.
- Tao, Li-Ming,Li, Qiang-Guo,Liu, Wen-Qi,Zhou, Yun,Zhou, Ju-Feng
-
experimental part
p. 211 - 213
(2010/08/19)
-
- P[N(i-Bu)CH2CH2]3N: Nonionic Lewis base for promoting the room-temperature synthesis of α,β-unsaturated esters, fluorides, ketones, and nitriles using Wadsworth - Emmons phosphonates
-
The bicyclic triaminophosphine P(RNCH2CH2) 3N (R = i-Bu, 1c) serves as an effective promoter for the room-temperature stereoselective synthesis of α,β-unsaturated esters, fluorides, and nitriles from a wide array of aromatic, aliphatic, heterocyclic, and cyclic aldehydes and ketones, using a range of Wadsworth-Emmons (WE) phosphonates. Among the analogues of 1c [R = Me (1a), i-Pr (1b), Bn (1d)], 1a and 1b performed well, although longer reaction times were involved, and 1d led to poorer yields than 1c. Functionalities such as cyano, chloro, bromo, methoxy, amino, ester, and nitro were well tolerated. We were able to isolate and characterize (by X-ray means; see above) the reactive WE intermediate species formed from 2b and 1c.
- Chintareddy, Venkat Reddy,Ellern, Arkady,Verkade, John G.
-
supporting information; experimental part
p. 7166 - 7174
(2010/12/25)
-
- Arylation of allylsilanes through rhodium catalysis
-
The arylation of allylsilanes catalyzed by a rhodium complex is described. In the presence of a catalytic amount of RhCl(CO){P[OCH(CF3) 2]3}2 and Ag2C03, allyltriisopropylsilane reacts with iodoarenes
- Omachi, Haruka,Itami, Kenichiro
-
scheme or table
p. 186 - 187
(2010/02/16)
-
- N-heterocycle carbene (NHC)-ligated cyclopalladated N,N- dimethylbenzylamine: A highly active, practical and versatile catalyst for the Heck-Mizoroki reaction
-
The wide dissemination of catalytic protocols in academic and industrial laboratories is facilitated by the development of catalysts that are not only highly active but also user-friendly, stable to moisture, air and long term storage and easy to prepare on a large scale. Herein we describe a protocol for the Heck-Mizoroki reaction mediated by cyclopalladN-dimethylbenzylamine (dmba) ligated ne, 1,3-bdot;HCl in refluxing acetonitrile in air in the presence of K2CO in iates the H bromides in reagent grade NMP at the 0.1-2 mol% range without the need for rigorous anhydrous techniques or a glovebox, and is active even in air. The catalyst is capable of achieving very high levels of catalytic activity (TON of up to 5.22 × 105) for the coupling of a deactivated arylbromide, p-bromoanisole, with tBu acrylate as a benchmark substrate pair. A wide range of aryl bromides, iodides and, for the first time with a NHC-Pd catalyst, a triflate was coupled with diverse acrylate derivatives (nitrile, tert-butyl ester and amides) and styrene derivatives. The use of excess (>2 equiv.) of the aryl bromide and tert-butyl acrylate leads to mixture of tert-butyl β,β-diarylacrylate and tert-butyl cinnamate derivatives depending on the substitution pattern of the aryl bromide. Electron rich m- and p-substituted arylbromides give the diarylated products exclusively, whereas electron-poor aryl bromides give predominantly mono-arylated products. For o-substituted aryl bromides, no doubly arylated products could be obtained under any conditions. Overall, the active catalyst (IMes-Pd) shows higher activity with electron-rich aryl halides, a marked difference compared with the more commonly used phosphane-Pd or non-ligated Pd catalysts.
- Peh, Guang-Rong,Kantchev, Eric Assen B.,Zhang, Chi,Ying, Jackie Y.
-
supporting information; experimental part
p. 2110 - 2119
(2009/09/05)
-
- Heck cross-coupling of aryldiazonium tetrafluoroborate with acrylates catalyzed by palladium on charcoal
-
A property-activity relationship study of various palladium supported on charcoal (Pd/C) catalysts has been undertaken for the Heck reaction of aryldiazonium tetrafluoroborate with acrylates. The optimized protocol enables the cross-coupling with a low loading of palladium at room temperature in technical grade methanol. Although the catalyst could not be recycled at this time, measurement of the palladium content by inductively coupled plasma mass spectrometry (ICP-MS) shows low palladium contamination of the solvent and product, rendering this method safer for the environment compared to homogeneous conditions.
- Felpin, Francois-Xavier,Fouquet, Eric,Zakri, Cecile
-
experimental part
p. 2559 - 2565
(2009/08/14)
-
- Cinnamoyl inhibitors of tissue transglutaminase
-
(Figure Presented) Transglutaminases (TGases) catalyze the intermolecular cross-linking of certain proteins and tissue TGases (TG2) are involved in diverse biological processes. Unregulated, high TGase activities have been implicated in several physiological disorders, but few reversible inhibitors of TG2 have been reported. Herein, we report the synthesis of a series of novel trans-cinammoyl derivatives, discovered to be potent inhibitors of guinea pig liver transglutaminase. The most effective inhibitors evaluated can be sorted into two subclasses: substituted cinnamoyl benzotriazolyl amides and the 3-(substituted cinnamoyl)pyridines, referred to more commonly as azachalcones. Kinetic evaluation of both of these subclasses revealed that they display reversible inhibition and are competitive with acyl donor TGase substrates at IC50 values as low as 18 μM. An analysis of structure - activity relationships within these series of inhibitors permitted the identification of potentially important binding interactions. Further testing of some of the most potent inhibitors demonstrated their selectivity for TG2 and their potential for further development.
- Pardin, Christophe,Pelletier, Joelle N.,Lubell, William D.,Keillor, Jeffrey W.
-
p. 5766 - 5775
(2008/12/22)
-
- An inexpensive and highly stable ligand 1,4-bis(2-hydroxy-3,5-di-tert-butylbenzyl)piperazine for Mizoroki-Heck and room temperature Suzuki-Miyaura cross-coupling reactions
-
A bulky, inexpensive and simple bidentate ligand 1,4-bis(2-hydroxy-3,5-di-tert-butylbenzyl)piperazine (1) has been synthesized and characterized. The palladium catalyst was formed by combination of 1 with [Cl2Pd(COD)] in a ratio of 1:1, tested in the Suzuki-Miyaura and Mizoroki-Heck cross-coupling reactions. Coupling of a variety of aryl bromides with phenylboronic acid using methanol as solvent at room temperature, or at 60 °C, gave generally high yields of coupled products. Coupling of aryl chlorides with organoboron reagent at 110 °C in DMF afforded good yields of biaryls under aerobic conditions. This non-phosphorus, air and moisture stable catalyst also displays good activity for Mizoroki-Heck coupling reaction in methanol at 60 °C with various aryl chlorides and bromides.
- Mohanty, Sasmita,Suresh,Balakrishna, Maravanji S.,Mague, Joel. T.
-
p. 240 - 247
(2008/09/16)
-
- Microwave-assisted Suzuki-Miyaura and Heck-Mizoroki cross-coupling reactions of aryl chlorides and bromides in water using stable benzothiazole-based palladium(II) precatalysts
-
The catalytic activity of benzothiazole-based Pd(II)-complexes was evaluated in Suzuki-Miyaura and Heck-Mizoroki C-C cross-coupling reactions of aryl chlorides and bromides with olefins and arylboronic acids both under thermal as well as microwave irradiation conditions in water. The factors affecting the optimization of such reactions as well as the reusability of the Pd-precatalysts are studied.
- Dawood, Kamal M.
-
p. 9642 - 9651
(2008/02/12)
-
- Oxidative palladium(II) catalysis: A highly efficient and chemoselective cross-coupling method for carbon-carbon bond formation under base-free and nitrogenous-ligand conditions
-
We report herein the development of a general and mild protocol of oxygen-promoted Pd(II) catalysis resulting in the selective cross-couplings of alkenyl- and arylboron compounds with various olefins. Unlike most cross-coupling reactions, this new methodology works well even in the absence of bases, consequently averting undesired homo-couplings. Nitrogen-based ligands including dimethyl-phenanathroline enhance reactivities and offer a highly efficient and stereoselective methodology to overcome challenging substrate limitations. For instance, oxidative palladium(II) catalysis is effective with highly substituted alkenes and cyclic alkenes, which are known to be incompatible with other known catalytic conditions. Most examined reactions progressed smoothly to completion at low temperatures and in short times. These interesting results provide mechanistic insights and utilities for a new paradigm of palladium catalytic cycles without bases.
- Yoo, Kyung Soo,Yoon, Cheol Hwan,Jung, Kyung Woon
-
p. 16384 - 16393
(2007/10/03)
-
- PEG-400 promoted Pd(OAc)2/DABCO-catalyzed cross-coupling reactions in aqueous media
-
PEG-400 [poly(ethylene glycol-400)] was found to improve the Pd(OAc) 2/DABCO-catalyzed aqueous Suzuki-Miyaura and Stille cross-coupling reactions. In the presence of Pd(OAc)2, DABCO, and PEG-400, a variety of aryl halides were coupled with arylboronic acids or organotin compounds efficiently to afford the corresponding cross-coupled products in moderate to excellent yields. The turnover numbers was up to 900,000 for the Suzuki-Miyaura reaction and up to 9800 for the Stille reaction. The catalyst system was also effective for Heck and Sonogashira cross-coupling reactions to some extent.
- Li, Jin-Heng,Hu, Xi-Chao,Liang, Yun,Xie, Ye-Xiang
-
-
- Microwave-assisted copper-catalyzed heck reaction in PEG solvent
-
A catalytic system made of a copper salt, potassium carbonate and PEG 3400 was developed to perform a Heck arylation under microwave activation. Copper iodide gave the best results in a short reaction time (30 min) and various substituted tert-butyl cinna
- Declerck, Valérie,Martinez, Jean,Lamaty, Frédéric
-
p. 3029 - 3032
(2008/02/13)
-
- The one-pot Wittig reaction: A facile synthesis of α,β- unsaturated esters and nitriles by using nanocrystalline magnesium oxide
-
Nanocrystalline magnesium oxide was found to be an effective heterogeneous, solid base catalyst for the one-pot Wittig reaction to afford α,β-unsaturated esters and nitriles in excellent yields with high E-stereoselectivity in the presence of triphenylphosphine under mild conditions.
- Choudary, Boyapati M.,Mahendar, Koosam,Kantam, M. Lakshmi,Ranganath, Kalluri V. S.,Athar, Taimur
-
p. 1977 - 1985
(2007/10/03)
-
- Pd(OAc)2/DABCO as a highly active catalytic system for the heck reaction
-
The combination of Pd(OAc)2 and DABCO (triethylenediamine) was observed as an efficient catalytic system for the Heck cross-coupling reaction. In the presence of Pd(OAc)2 and DABCO, a number of ArX (X = I, Br, and Cl) were coupled with olefins efficiently and selectively to afford the corresponding unsymmetric internal olefins in good to excellent yields. Furthermore, the Pd(OAc)2/DABCO-catalyzed Heck cross-coupling reaction provided high TONs up to 1,000,000. Georg Thieme Verlag Stuttgart.
- Li, Jin-Heng,Wang, De-Ping,Xie, Ye-Xiang
-
p. 2193 - 2197
(2007/10/03)
-
- CuI/Dabco as a highly active catalytic system for the Heck-type reaction
-
An efficient catalytic system using CuI/Dabco (triethylenediamine) for the Heck-type cross-coupling reaction was developed. In the presence of 10 mol % of CuI and 20 mol % of Dabco, the coupling of various aromatic iodides and 1-((Z)-2-bromovinyl)benzene
- Li, Jin-Heng,Wang, De-Ping,Xie, Ye-Xiang
-
p. 4941 - 4944
(2007/10/03)
-
- Wittig-type olefination catalyzed by PEG-telluride
-
Soluble poly(ethylene glycol) (PEG)-supported telluride 2 was designed and synthesized for catalytic Wittig-type reactions. It was found that the catalytic loading could be reduced from 20 to 2 mol % by the introduction of PEG (even to 0.5 mol % when some telluride salts were used as the catalyst). Under the catalytic reaction conditions, a wide variety of aldehydes with different structures could react with bromoacetate to afford β-substituted or α,β-disubstituted unsaturated esters in high yields with excellent E-stereoselectivity. The modified process, by using sodium bisulfite instead of triphenyl phosphite, represented a very simple product isolation procedure. The roles of PEG for promoting the ylide formation and stabilizing the catalytic species were disclosed. The mechanism was also studied.
- Huang, Zheng-Zheng,Ye, Song,Xia, Wei,Yu, Yi-Hua,Tang, Yong
-
p. 3096 - 3103
(2007/10/03)
-
- Enantioselective aziridination using copper complexes of biaryl Schiff bases
-
Racemic 2,2′-diamino-6,6′-dimethylbiphenyl is resolved using simulated moving bed chromatography, and the absolute configuration of the enantiomers is confirmed via the X-ray crystal structure of a derivative. The diamine is condensed with a range of aldehydes to give bidentate aldimine proligands L. Molecular structures of the complexes formed between L and Cu(I) fall into two classes; bimetallic double helices ([Cu2L2]2+) and monometallic ([CuL]+). The latter are strikingly more efficient in the aziridination of alkenes than are the former in terms of rate, turnover, and enantioselection. In particular, the imine ligand formed from the diamine and 2,6-dichlorobenzaldehyde gives, in combination with Cu(I) or Cu(II), up to 99% ee in the aziridination of 6-acyl-2,2-dimethylchromene and 88-98% ee for a range of cinnamate esters. Styrenic and other alkenes are converted with lower selectivities (5-54%). The catalytic system shows a linear response in product ee to catalyst ee, and the product ee does not vary significantly during the reaction. UV spectrophotometric investigations indicate that conversion of Cu(I) to Cu(II) is not essential for catalysis but that Cu(II) is probably also a competent system.
- Gillespie, Kevin M.,Sanders, Christopher J.,O'Shaughnessy, Paul,Westmoreland, Ian,Thickitt, Christopher P.,Scott, Peter
-
p. 3450 - 3458
(2007/10/03)
-
- Highly active Pd(II) catalysts with trans-bidentate pyridine ligands for the Heck reaction
-
(Matrix presented) The air-, water-, and heat-stable palladium(II) complexes 2a and 2b are prepared by the reaction of palladium(II) salts with the new transbidentate nitrogen ligands, 1,2-bis(2-pyridylethynyl)benzenes. The structure of complex 2a has bee
- Kawano, Tomikazu,Shinomaru, Tatsuji,Ueda, Ikuo
-
p. 2545 - 2547
(2007/10/03)
-
- A practical catalytic Wittig-type reaction
-
Soluble PEG-supported telluride 2 was synthesized and found to be an effective catalyst for the catalytic Wittig-type reaction to give a variety of α,β-unsaturated esters in high yields with excellent E-stereoselectivity in the presence of sodium bisulfite as well as triphenyl phosphite.
- Huang,Ye,Xia,Tang
-
p. 1384 - 1385
(2007/10/03)
-