- N-Heterocyclic carbene palladium (II)-pyridine (NHC-Pd (II)-Py) complex catalyzed heck reactions
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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
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supporting information
p. 2041 - 2052
(2021/05/25)
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- Lipids as versatile solvents for chemical synthesis
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Development of safe, renewable, cheap and versatile solvents is a longstanding challenge in chemistry. We show here that vegetable oils and related systems can become prominent solvents for organic synthesis. Suzuki-Miyaura, Hiyama, Stille, Sonogashira and Heck cross-couplings proceed with quantitative yields in a range of vegetable oils, fish oil, butter and waxes used as solvents. Appropriate methodologies for high-throughput screening and sustainable isolation techniques applicable for vegetable oils and related lipids are presented.
- Bayer, Annette,Gevorgyan, Ashot,Hopmann, Kathrin H.
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supporting information
p. 7219 - 7227
(2021/09/28)
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- Palladium-Catalyzed Mizoroki-Heck Reaction of Nitroarenes and Styrene Derivatives
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We have developed a Mizoroki-Heck reaction of nitroarenes with alkenes under palladium catalysis. The use of a Pd/BrettPhos catalyst promoted the alkenylation, whereas other catalysts led to a decrease in the product yield. In addition to nitroarenes, nitroheteroarenes were also applicable to the present reaction. The combination of a nucleophilic aromatic substitution (SNAr) with the denitrative alkenylation produced a multifunctionalized arene in a one-pot operation.
- Okita, Toshimasa,Asahara, Kitty K.,Muto, Kei,Yamaguchi, Junichiro
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supporting information
p. 3205 - 3208
(2020/04/10)
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- 1-Aryltriazenes in the Suzuki, Heck, and Sonogashira Reactions in Imidazolium-ILs, with [BMIM(SO3H)][OTf] or Sc(OTf)3 as Promoter, and Pd(OAc)2 or NiCl2·glyme as Catalyst
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1-Aryltriazenes, the protected and more stable form of aryl-diazonium species, can be conveniently unmasked with Br?nsted acidic-IL or Sc(OTf)3 and coupled with a host of aryl/heteroaryl boronic acids, styrenes, and aryl/alkyl acetylenes in the Suzuki, Heck and Sonogashira reactions in one-pot and in respectable isolated yields, by using palladium or nickel catalyst in readily available imidazolium ILs as solvent, under mild conditions. The scope of these reactions are explored, and the potential for recovery/reuse of the IL solvent is also addressed.
- Sutar, Suraj M.,Savanur, Hemantkumar M.,Malunavar, Shruti S.,Prabhala, Pavankumar,Kalkhambkar, Rajesh G.,Laali, Kenneth K.
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supporting information
p. 6088 - 6093
(2019/09/17)
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- Olefination with Sulfonyl Halides and Esters: E-Selective Synthesis of Alkenes from Semistabilized Carbanion Precursors
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Carbanions of sulfonyl halides and activated sulfonates add to carbonyl compounds, and so-formed aldol-type adducts spontaneously fragment into olefins. This transformation mimics the one-pot Julia olefination with (hetero)aryl sulfones, but the mechanism of fragmentation involves a four-membered intermediate, typical for reactivity of phosphorus reagents. Moreover, in contrast to the reactions of sulfones, sulfonates of fluorinated alcohols (TFE and HFI) produce byproducts that are easily removed during workup. In our report, we focus on reactions of unstabilized and semistabilized carbanion precursors: alkylsulfonates, and allyl- and benzylsulfonates, respectively. In particular for semistabilized systems, olefins were synthesized as predominant E isomers in good yields. The presented studies reveal that optimal reaction conditions, including the type of base and alcohol groups of the sulfonates, are different depending on stabilization of the carbanion precursors and structure of the carbonyl substrates. The practical synthetic guide is supplemented with a discussion of the mechanism, based on reactivity studies of intermediates and identification of side-products.
- Górski, Bartosz,Basiak, Dariusz,Talko, Alicja,Basak, Tymoteusz,Mazurek, Tomasz,Barbasiewicz, Micha?
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p. 1774 - 1784
(2018/04/27)
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- Practical Cross-Coupling between O-Based Electrophiles and Aryl Bromides via Ni Catalysis
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Cross-coupling of various O-based electrophiles with aryl bromides was developed through Ni-catalyzed C-O activation in the presence of magnesium. Beside carboxylates, carbamates, and ethers, phenols exhibited excellent reactivity under modified conditions. This chemistry was featured as a simple and environmentally benign process with low catalyst loading and easy manipulations. The method exhibited broad substrate scopes.
- Cao, Zhi-Chao,Luo, Qin-Yu,Shi, Zhang-Jie
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supporting information
p. 5978 - 5981
(2016/12/09)
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- Nickel-catalyzed synthesis of (E)-olefins from benzylic alcohol derivatives and arylacetonitriles via C-O activation
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An efficient Ni-catalyzed synthesis of (E)-olefins using the readily available benzylic alcohol derivatives and arylacetonitriles is described. This transformation should proceed via a tandem process involving nickel-catalyzed cross coupling via C-O activation and subsequent stereoselective E2 elimination.
- Xiao, Jing,Yang, Jia,Chen, Tieqiao,Han, Li-Biao
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p. 2157 - 2160
(2016/02/05)
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- N,N′-Mono substituted acyclic thioureas: Efficient ligands for the palladium catalyzed Heck reaction of deactivated aryl bromides
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A series of N,N′-mono substituted acyclic thiourea ligands are found to be highly active phosphine-free catalysts for palladium catalyzed Heck reaction of aryl iodides and bromides with olefins. We have achieved high turnover numbers for aryl iodides with olefins (TONs up to 970,000 for the reaction of iodobenzene with styrene).
- Keesara, Srinivas,Parvathaneni, Saiprathima,Mandapati, Mohan Rao
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p. 6769 - 6772
(2015/05/05)
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- Selective arylation and vinylation at the α position of vinylarenes
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In intermolecular Heck reactions of styrene and vinylarenes, the aryl and vinyl groups routinely insert at the β position. However, selective insertion at the α position has been very rare. Herein, we provide a missing piece in the palette of Heck reaction, which gave >20:1 α selectivity. The key to our success is a new ferrocene 1,1′-bisphosphane (dnpf) that carries 1-naphthyl groups. Our mechanistic studies revealed that the high α selectivity is partly attributable to the steric effect of dnpf. The rigid and bulky 1-naphthyl groups of dnpf sterically disfavor β insertion. What the Heck! In intermolecular Heck reactions, insertion at the β position of aromatic olefins is very common, but reversal of the selectivity for selective α insertion has been a longstanding problem. A general method to couple aryl and vinyl triflates with aromatic olefins in >20:1 α selectivity is presented. The key to this successful approach is a new ferrocene bisphosphane with naphthyl groups on the phosphorus atom (see scheme; OTf=triflate). Copyright
- Zou, Yinjun,Qin, Liena,Ren, Xinfeng,Lu, Yunpeng,Li, Yongxin,Zhou, Jianrong
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supporting information
p. 3504 - 3511
(2013/07/05)
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- Oxidative Mizoroki-Heck-type reaction of arylsulfonyl hydrazides for a highly regio- and stereoselective synthesis of polysubstituted alkenes
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A useful source: Arylsulfonyl hydrazides have been identified as synthetically useful aryl sources for the Pd(OAc)2 catalyzed oxidative Mizoroki-Heck-type reaction under molecular oxygen to provide a convenient access to polysubstituted alkenes in a highly regio- and stereoselective manner (see scheme). The reaction well tolerates various functional groups such as alkoxy, halo, alcohol, carboxylic acid, ester, amide, sulfonamide, and sulfone. Copyright
- Yang, Fu-Lai,Ma, Xian-Tao,Tian, Shi-Kai
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supporting information; experimental part
p. 1582 - 1585
(2012/03/11)
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- Expeditious synthesis of helicenes using an improved protocol of photocyclodehydrogenation of stilbenes
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An improved procedure has been developed for photodehydrocyclization of stilbenes for the synthesis of phenanthrenes and helicenes. This procedure involves the use of THF as a scavenger of hydriodic acid produced during iodine mediated photodehydrocyclization. The use of THF is advantageous due to its higher boiling point, lower cost and easy availability as compared to propylene oxide. The method is applied to synthesize a number of phenanthrenes and helicenes. ARKAT-USA, Inc.
- Talele, Harish R.,Chaudhary, Anju R.,Patel, Parthiv R.,Bedekar, Ashutosh V.
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- Studies toward the photochemical synthesis of functionalized [5]- and [6] carbohelicenes
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(Chemical Equation Presented) An efficient route to nonsymmetrical helical menthyl esters by means of an oxidative photocyclization reaction of dissymmetric bis-stilbenes is reported. The developed route allows the introduction of functionality on rings A, E, or F, and the influence of the substituent pattern on the photochemical reaction has been examined. Diastereoselectivity is observed when a double chiral induction strategy with dimenthyl helicene esters synthesized in a 70:30 ratio of isomers is used.
- Pearson, Morwenna S. M.,Carbery, David R.
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supporting information; experimental part
p. 5320 - 5325
(2009/11/30)
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- Highly efficient fluorine-promoted intramolecular condensation of benzo[c]phenanthrene: A new prospective on direct fullerene synthesis
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Various functional groups have been tested as alternative promoters of the intramolecular condensation of benzo-[c]phenanthrene under flash vacuum pyrolysis conditions. Methyl and fluorine functionalization were found to be promising approaches. Unexpectedly high selectivity was observed in the cyclization of fluorinated benzo[c]phenanthrenes. The mechanism for the condensation reaction and the advantages of fluorine as a promoter for the rational synthesis of fullerenes are discussed. Wiley-VCH Verlag GmbH & Co. KGaA.
- Amsharov, Konstantin Yu.,Kabdulov, Mikhail A.,Jansen, Martin
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p. 6328 - 6335
(2011/03/19)
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- Further naphthylcombretastatins. An investigation on the role of the naphthalene moiety
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By synthesis and biological studies of new naphthalene analogues of combretastatins, we have found that the naphthalene is a good surrogate for the isovanillin moiety (3-hydroxy-4-methoxyphenyl) of combretastatin A-4, always generating highly cytotoxic analogues when combined with the 3,4,5-trimethoxyphenyl or related systems. On the other hand, when the naphthalene replaces the 3,4,5-trimethoxyphenyl moiety, the cytotoxic activity is largely decreased. The most cytotoxic naphthalene analogues of combretastatins, which also produce inhibition of tubulin polymerization, exerted their antimitotic effects through microtubule network disruption and subsequent G2/M arrest of the cell cycle in human cancer cells.
- Maya, Ana B. S.,Pérez-Melero, Concepción,Mateo, Carmen,Alonso, Dulce,Fernández, José Luis,Gajate, Consuelo,Mollinedo, Faustino,Peláez, Rafael,Caballero, Esther,Medarde, Manuel
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p. 556 - 568
(2007/10/03)
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- Triaryl phosphine-functionalized N-heterocyclic carbene ligands for Heck reaction
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A new type of triaryl phosphine-functionalized imidazolium salts 6 were prepared. Their palladium complexes, generated in situ, were successfully applied in the palladium-catalyzed Heck reaction. Using 1 mol% of Pd(dba) 2 and 1 mol% 6c in the presence of 2 equiv of K2CO 3 in DMAc has proven to be highly efficient for the coupling of a wide array of aryl bromides and iodides with acrylates in excellent yield. The coupling of 4-bromotoluene with various styrene derivatives catalyzed by Pd/6c complex also gave good results. Graphical Abstract.
- Wang, Ai-E,Xie, Jian-Hua,Wang, Li-Xin,Zhou, Qi-Lin
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p. 259 - 266
(2007/10/03)
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- A new synthesis of corannulene
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Flash vacuum pyrolysis of 2-substituted benzo[c]phenanthrene has been exploited as a pivotal step in a new, simple synthesis of the 'bowl-shaped' hydrocarbon corannulene 1.
- Mehta, Goverdhan,Panda, Gautam
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p. 2145 - 2148
(2007/10/03)
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- Influence of the vinyl group on the calcium antagonistic activity of analogues of Fostedil
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Four aryl vinyl diethyl benzylphosphonates related to Fostedil were synthesized and evalued for their in vitro calcium-inhibitory activity.None of these compounds exhibited any calcium antagonistic profile.Unlike a series of diethyl-styryl benzylphosphona
- Tchani, G.,Baziard-Mouysset, G.,Stigliani, J. L.,Payard, M.,Bonnafous, R.,Tisne-Versailles, J.
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p. 173 - 179
(2007/10/02)
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