- Electrochemical Decarboxylative Cyclization of α-Amino-Oxy Acids to Access Phenanthridine Derivatives
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Phenanthridines are a class of useful heterocycles in the field of drug development. In this work, a method via electrochemical decarboxylative cyclization of α-amino-oxy acids to access phenanthridine derivatives was developed. This reaction proceeded th
- Zhan, Yanling,Dai, Changhui,Zhu, Zitong,Liu, Ping,Sun, Peipei
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supporting information
(2022/02/07)
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- Gold Catalysts Can Generate Nitrone Intermediates from a Nitrosoarene/Alkene Mixture, Enabling Two Distinct Catalytic Reactions: A Nitroso-Activated Cycloheptatriene/Benzylidene Rearrangement
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Gold-catalyzed reactions of cycloheptatrienes with nitrosoarenes yield nitrone derivatives efficiently. This reaction sequence enables us to develop gold-catalyzed aerobic oxidations of cycloheptatrienes to afford benzaldehyde derivatives using CuCl and nitrosoarenes as co-catalysts (10-30 mol %). Our density functional theory calculations support a novel nitroso-activated rearrangement, tropylium → benzylidene. With the same nitrosoarenes, we developed their gold-catalyzed [2 + 2 + 1]-annulations between nitrosobenzene and two enol ethers to yield 5-alkoxyisoxazolidines using 1,4-cyclohexadienes as hydrogen donors.
- Cheng, Mu-Jeng,Kardile, Rahul Dadabhau,Kuo, Tung-Chun,Liu, Rai-Shung,More, Sayaji Arjun
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p. 5506 - 5511
(2021/07/31)
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- Base-Free Suzuki–Miyaura Coupling Reaction Using Palladium(II) Supported Catalyst in Water
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Abstract: The carbon–carbon bond formation via Suzuki–Miyaura reaction was performed in water as green solvent. Pd(OAc)2(PPh3)2 supported on magnesium hydroxide and cerium carbonate hydroxide composite was prepared and characterized by various techniques. The cross-coupling reaction of aryl halides carried out in water using mild conditions. The effects of temperature, solvents, the amount of catalyst and leaving groups were studied to find the optimization conditions for cross-coupling reaction. Various aryl halides were smoothly transformed into the biaryls in good yields. In addition, the catalyst also exhibited stability and catalytic performance in the cross-coupling of aryl halides. Graphical Abstract: [Figure not available: see fulltext.] A new approach is developed for carbon–carbon bond formation via Suzuki–Miyaura reaction.2 Pd(OAc)2(PPh3)2?supported on mixed magnesium hydroxide and cerium carbonate hydroxide were prepared and characterized by XRD, XPS, SEM–EDX techniques. The cross-coupling reaction of aryl halides can be carried out in water and under mild conditions (80 °C).
- Tomar, Ravi,Singh, Nidhi,Kumar, Neeraj,Tomar, Vartika,Chandra, Ramesh
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- Indolylbenzimidazole-based ligands catalyze the coupling of arylboronic acids with aryl halides
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A novel class of compounds bearing indole and benzimidazole rings was designed and easily synthesized from 2-indolecarboxylic acid and o-phenylenediamine. The catalytic system derived from a 2-indolylbenzimidazole-based ligand and Pd(OAc)2 in situ could lead to complete conversion of aryl bromides at 0.5?mol% Pd loading under mild reaction conditions. In the presence of a catalyst, sterically hindered biaryls were selectively generated in excellent yields by adjusting reaction parameters through the coupling of arylboronic acids with aryl halides. The efficiency of this reaction was demonstrated by its compatibility with various functional groups.
- Wang, Meng-Pei,Chiu, Chien-Cheng,Lu, Ta-Jung,Lee, Dong-Sheng
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- Atroposelective Synthesis of Axially Chiral Biaryls by Palladium-Catalyzed Asymmetric C?H Olefination Enabled by a Transient Chiral Auxiliary
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Atroposelective synthesis of axially chiral biaryls by palladium-catalyzed C?H olefination, using tert-leucine as an inexpensive, catalytic, and transient chiral auxiliary, has been realized. This strategy provides a highly efficient and straightforward access to a broad range of enantioenriched biaryls in good yields (up to 98 %) with excellent enantioselectivities (95 to >99 % ee). Kinetic resolution of trisubstituted biaryls bearing sterically more demanding substituents is also operative, thus furnishing the optically active olefinated products with excellent selectivity (95 to >99 % ee, s-factor up to 600).
- Yao, Qi-Jun,Zhang, Shuo,Zhan, Bei-Bei,Shi, Bing-Feng
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supporting information
p. 6617 - 6621
(2017/05/29)
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- Silver-Catalyzed Tandem C=C Bond Hydroazidation/Radical Addition/Cyclization of Biphenyl Acetylene: One-Pot Synthesis of 6-Methyl Sulfonylated Phenanthridines
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A silver-catalyzed tandem carbon-carbon triple bond hydroazidation, radical addition, and cyclization of biphenyl acetylene is described under mild conditions, leading to the formation of 6-methyl sulfonylated phenanthridines in good yields. In this novel cascade reaction, most of the atoms are incorporated into the product without cleavage of the C=C bond. Mechanistic studies suggest the reaction should proceed through an iminyl radical reactive intermediate.
- Tang, Jiawei,Sivaguru, Paramasivam,Ning, Yongquan,Zanoni, Giuseppe,Bi, Xihe
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supporting information
p. 4026 - 4029
(2017/08/14)
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- Amide-Directed C?H Sodiation by a Sodium Hydride/Iodide Composite
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A new protocol for amide-directed ortho and lateral C?H sodiation is enabled by sodium hydride (NaH) in the presence of either sodium iodide (NaI) or lithium iodide (LiI). The transient organosodium intermediates could be transformed into functionalized aromatic compounds.
- Huang, Yinhua,Chan, Guo Hao,Chiba, Shunsuke
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supporting information
p. 6544 - 6547
(2017/05/29)
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- (Biphenyl-2-alkyne) derivatives as common precursors for the synthesis of 9-iodo-10-organochalcogen-phenanthrenes and 9-organochalcogen-phenanthrenes
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In this paper, we report our results on the cyclization of (biphenyl-2-alkyne) derivatives to give two different types of phenanthrene derivatives, 9-iodo-10-organochalcogen-phenanthrenes and 9-organochalcogen-phenanthrenes. The strategy for the synthesis was based on the use of electrophilic cyclization for the preparation of 9-iodo-10-organochalcogen-phenanthrenes and iron(iii) chloride/diorganyl diselenide-mediated intramolecular cyclization to prepare 9-organochalcogen-phenanthrenes. The effects of solvent, temperature, reaction time and stoichiometry on the efficiency of cyclization reactions were investigated. The standard reaction conditions were compatible with many functional groups in the substrates, such as methyl, chlorine, fluorine and methoxyl. This protocol was efficient for diorganyl diselenides and disulfides but ineffective for diorganyl ditellurides. The resulting phenanthrenes were further functionalized through Sonogashira reactions followed by the electrophilic cyclization reaction to give the selenophene-fused aromatic compounds.
- Grimaldi, Tamiris B.,Lutz, Guilherme,Back, Davi F.,Zeni, Gilson
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p. 10415 - 10426
(2016/11/18)
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- Rapid threefold cross-couplings with sterically bulky triarylbismuths under Pd-Cu dual catalysis
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The threefold cross-coupling reactivity of sterically highly demanding bulky triarylbismuths was addressed with task specific Pd-Cu dual catalytic conditions. In this study, an unprecedented hitherto unknown cross-coupling reactivity of sterically bulky triarylbismuths was demonstrated with a diverse range of aryl iodides and bromides. The intermediacy and in situ formation of arylcopper was probed with mesitylcopper in support of the proposed dual catalysis. This study opened up an easy way forward for application of sterically bulky bismuth reagents in threefold aryl-aryl coupling reactions.
- Rao, Maddali L. N.,Dhanorkar, Ritesh J.
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p. 1012 - 1017
(2016/01/16)
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- Copper catalyzed room temperature lactonization of aromatic C-H bond: A novel and efficient approach for the synthesis of dibenzopyranones
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We have developed a novel and efficient methodology for the intramolecular aryl C-H oxidative lactonization of 2-arylbenzaldehyde using a low-cost CuCl catalyst and TBHP as the oxidant at room temperature. We applied the methodology to the synthesis of a series of dibenzopyranones.
- Singha, Raju,Dhara, Shubhendu,Ghosh, Munmun,Ray, Jayanta K.
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p. 8801 - 8805
(2015/03/03)
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- A highly water-dispersible/magnetically separable palladium catalyst based on a Fe3O4@SiO2 anchored TEG-imidazolium ionic liquid for the Suzuki-Miyaura coupling reaction in water
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A novel ionic liquid functionalized magnetic nanoparticle was prepared by anchoring an imidazolium ionic liquid bearing triethylene glycol moieties on the surface of silica-coated iron oxide nanoparticles. The material proved to be an effective host for the immobilization of a Pd catalyst through a subsequent simple ion-exchange process giving a highly water dispersible, active and yet magnetically recoverable Pd catalyst (Mag-IL-Pd) in the Suzuki-Miyaura coupling reaction in water. The as-prepared catalyst displayed remarkable activity toward challenging substrates such as heteroaryl halides and ortho-substituted aryl halides as well as aryl chlorides using very low Pd loading in excellent yields and demonstrating high TONs. Since the catalyst exhibited extremely low solubility in organic solvent, the recovered aqueous phase containing the catalyst can be simply and efficiently used in ten consecutive runs without significant decrease in activity and at the end of the process can be easily separated from the aqueous phase by applying an external magnetic field. This novel double-separation strategy with negligible leaching makes Mag-IL-Pd an eco-friendly and economical catalyst to perform this transformation. the Partner Organisations 2014.
- Karimi, Babak,Mansouri, Fariborz,Vali, Hojatollah
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p. 2587 - 2596
(2014/05/06)
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- Synthesis, crystal structures and catalytic activity of three cyclopalladated 6-bromo-2-ferrocenylquinoline complexes with N-heterocyclic carbenes (NHCs) and triphenylphosphine
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Three cyclopalladated 6-bromo-2-ferrocenylquinoline complexes with NHCs and PPh3 1-3 have been synthesized and characterized by elemental analysis, IR, NMR and single-crystal X-ray diffraction. Their application to Suzuki coupling of phenylboro
- Xu, Chen,Li, Hong-Mei,Wang, Zhi-Qiang,Fu, Wei-Jun
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- Synthesis, crystal structures and catalytic activity of three cyclopalladated 6-bromo-2-ferrocenylquinoline complexes with N-heterocyclic carbenes (NHCs) and triphenylphosphine
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Three cyclopalladated 6-bromo-2-ferrocenylquinoline complexes with NHCs and PPh3 1-3 have been synthesized and characterized by elemental analysis, IR, NMR and single-crystal X-ray diffraction. Their application to Suzuki coupling of phenylboronic acid co
- Xu, Chen,Li, Hong-Mei,Wang, Zhi-Qiang,Fu, Wei-Jun
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- Synthesis, crystal structures and catalytic activity of three cyclopalladated 6-bromo-2-ferrocenylquinoline complexes with N-heterocyclic carbenes (NHCs) and triphenylphosphine
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Three cyclopalladated 6-bromo-2-ferrocenylquinoline complexes with NHCs and PPh31-3 have been synthesized and characterized by elemental analysis, IR, NMR and single-crystal X-ray diffraction. Their application to Suzuki coupling of phenylboron
- Xu, Chen,Li, Hong-Mei,Wang, Zhi-Qiang,Fu, Wei-Jun
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- Discovery of aryl-biphenyl-2-ylmethylpiperazines as novel scaffolds for 5-HT7 ligands and role of the aromatic substituents in binding to the target receptor
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It has been reported that 5-HT7 receptors are promising targets of depression and neuropathic pain. 5-HT7 receptor antagonists have exhibited antidepressant-like profiles, while agonists have represented potential therapeutics for pain. In the course of our ongoing efforts to discover novel 5-HT7 modulators, we designed an arylpiperazine scaffold with a substituted biphenyl-2-ylmethyl group. A series of biphenyl-2-yl-arylpiperazinylmethanes were then prepared, which showed a broad spectrum of binding affinities to the 5-HT7 receptor depending upon the substituents attached to the biphenyl and aryl functionalities. Among those synthesized compounds, the compounds 1-24 and 1-26 showed the best binding affinities to the 5-HT7 receptor with Ki values of 43.0 and 46.0 nM, respectively. Structure-activity relationship study in conjunction with molecular docking study proposed that the 5-HT7 receptor might have two distinctive hydrophobic binding sites, one specific for aromatic 2-OCH3 substituents within the arylpiperazine and the other for biphenyl methoxy group.
- Kim, Youngjae,Kim, Jeeyeon,Tae, Jinsung,Roth, Bryan L.,Rhim, Hyewhon,Keum, Gyochang,Nam, Ghilsoo,Choo, Hyunah
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p. 2568 - 2576
(2013/06/26)
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- Focused pseudostatic hydrazone libraries screened by mass spectrometry binding assay: Optimizing affinities toward γ-aminobutyric acid transporter 1
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Mass spectrometric (MS) binding assays, a powerful tool to determine affinities of single drug candidates toward chosen targets, were recently demonstrated to be suitable for the screening of compound libraries generated with reactions of dynamic combinatorial chemistry when rendering libraries pseudostatic. Screening of small hydrazone libraries targeting γ-aminobutyric acid transporter 1 (GAT1), the most abundant γ-aminobutyric acid (GABA) transporter in the central nervous system, revealed two nipecotic acid derived binders with submicromolar affinities. Starting from the biphenyl carrying hit as lead structure, the objective of the present study was to discover novel high affinity GAT1 binders by screening of biphenyl focused pseudostatic hydrazone libraries formed from hydrazine 10 and 36 biphenylcarbaldehydes 11c-al. Hydrazone 12z that carried a 2′,4′-dichlorobiphenyl residue was found to be the most potent binder with low nanomolar affinity (pKi = 8.094 ± 0.098). When stable carba analogues of representative hydrazones were synthesized and evaluated, the best binder 13z was again displaying the 2′,4′- dichlorobiphenyl moiety (pKi = 6.930 ± 0.021).
- Sindelar, Miriam,Lutz, Toni A.,Petrera, Marilena,Wanner, Klaus T.
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supporting information
p. 1323 - 1340
(2013/04/10)
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- Cross dehydrogenative coupling via base-promoted homolytic aromatic substitution (BHAS): Synthesis of fluorenones and xanthones
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Cross dehydrogenative coupling reactions occurring via base-promoted homolytic aromatic substitutions (BHASs) are reported. Fluorenones and xanthones are readily prepared via CDC starting with readily available ortho-formyl biphenyls and ortho-formyl biphenylethers, respectively. The commercially available and cheap tBuOOH is used as an oxidant. Initiation of the radical chain reaction is best achieved with small amounts of FeCp2 (0.1 or 1 mol %).
- Wertz, Sebastian,Leifert, Dirk,Studer, Armido
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supporting information
p. 928 - 931
(2013/03/28)
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- Polycationic ligands in gold catalysis: Synthesis and applications of extremely π-acidic catalysts
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Very often ligands are anionic or neutral species. Cationic ones are rare, and, when used, the positively charged groups are normally appended to the periphery of the ligand. Here, we describe a dicationic phosphine with no spacer between the phosphorus atom and the two positively charged groups. This structural feature makes its donor ability poorer than that of phosphites and only comparable to extremely toxic or pyrophoric compounds such as PF 3 or P(CF3)3. By exploiting these properties, a new Au catalyst has been developed displaying a dramatically enhanced capacity to activate π-systems. This has been used to synthesize very sterically hindered and naturally occurring 4,5-disubstituted phenanthrenes. The present approach is expected to be applicable to the development and improvement of many other transition metal catalyzed transformations that benefit from extremely strong π-acceptor ligands. The mechanism of selected catalytic transformations has been explored by density functional calculations.
- Carreras, Javier,Gopakumar, Gopinadhanpillai,Gu, Liangu,Gimeno, Ana,Linowski, Pawel,Petu?kova, Jekaterina,Thiel, Walter,Alcarazo, Manuel
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supporting information
p. 18815 - 18823
(2014/01/06)
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- Heterobimetallic Pd-Sn catalysis: A Suzuki, tandem ring-closing sequence toward indeno[2,1-b]thiophenes and indeno[2,1-b]indoles
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Indeno[2,1-b]thiophene and indeno[1,2-b]indole motifs have been obtained in moderate to good yields from easily available substituted boronic acids, 2-bromo aryl/vinyl aldehydes, and nucleophiles such as arenes/heteroarenes and others using a catalytic co
- Das, Debjit,Pratihar, Sanjay,Roy, Sujit
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supporting information
p. 4870 - 4873,4
(2020/09/16)
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- Ferrocenyl iminophosphine ligands in Pd-catalysed Suzuki couplings
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A mixture of Pd2(dba)3/{η-C5H 4CHN[CH(CH3)(Nap)]}Fe[η-C5H 4P(tBu)2] efficiently catalyzes the Suzuki reactions of a variety of bulky aryl halides and aryl- and alkyl-boronic acids, affording the desired cross-coupling biaryl products in quantitative isolated yields under mild conditions and at low (1 × 10-6-1 mol%) Pd loadings. Spectroscopic (NMR & ESI) analysis of the mixture of Pd 2(dba)3, the hybrid [P,N] ligands, and aryl halides revealed different structural forms of oxidative addition products that are dependent on the substituent on the imino nitrogen.
- Teo, Shihui,Weng, Zhiqiang,Hor, T.S. Andy
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experimental part
p. 2928 - 2934
(2011/08/05)
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- A novel water-soluble NHC-Pd polymer: An efficient and recyclable catalyst for the Suzuki coupling of aryl chlorides in water at room temperature
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A novel water-soluble NHC-Pd polymer with triethylene glycol legs was developed as a water soluble and highly recyclable catalyst that shows high catalytic activity in the Suzuki-Miyaura coupling of aryl chlorides in high yields in water at room temperature.
- Karimi, Babak,Fadavi Akhavan, Pari
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supporting information; experimental part
p. 7686 - 7688
(2011/09/12)
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- A study on applications of N-substituted main-chain NHC-palladium polymers as recyclable self-supported catalysts for the suzuki-miyaura coupling of aryl chlorides in water
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The preparation and characterization of a number of main-chain organometallic polymers (NHC-Pd MCOP) with different N-alkyl substituted groups such as benzyl (3a), n-hexyl (3b), and n-dodecyl (3c) are described. Among these polymers, 3c bearing the more lipophilic group n-dodecyl was found to be a more reactive and recoverable catalytic system in the Suzuki-Miyaura cross-coupling reaction of chloroarenes, including both deactivated and hindered aryl chlorides with different types of arylboronic acids under aqueous conditions. While the catalysts seem to be highly recyclable, on the contrary, we have provided much compelling evidence, such as kinetic monitoring, poisoning experiments, and average molecular weight determination before and after catalysis, that shows that the described organometallic polymers might be indeed the source of production of active soluble Pd species in the form of either Pd nanoparticles or fragmented NHC-Pd complexes. Our studies showed that in order to assess whether the catalysts are functioning in a heterogeneous pathway or they are simply a source of production of active Pd species, it is crucial to devise a suitable and highly efficient poison that could capture essentially soluble catalytic species. In this regard, we interestingly found that among a variety of well-known catalyst poisons such as Hg(0), SBA-15-PrSH, and cross-linked poly(4-vinylpyridine) (PVP), only PVP could efficiently quench catalysis, thus providing clear evidence of the formation soluble Pd species in our protocol. In addition, several experiments such as bright-field microscopy, dynamic light scattering (DLS) of the reaction mixture, and kinetic monitoring of the reaction at an early stage confirm not only that the described organometallic polymers could be a source of production of trace amounts of Pd nanoparticles but the capsular structures of these lipophilic polymers in water provides a means of entrapment of nanoclusters in a hydrophobic region, thus accelerating the reaction in pure water in the absence of any co-organic solvent.
- Karimi, Babak,Fadavi Akhavan, Pari
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scheme or table
p. 6063 - 6072
(2011/09/13)
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- Facile Cu(OTf)2-catalyzed preparation of 9-tosylaminofluorene derivatives from o-arylated N-tosylbenzaldimines
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The 9-tosylaminofluorene derivatives were synthesized conveniently by Cu(OTf)2-catalyzed aza-Friedel-Crafts reaction of o-arylated N-tosylbenzaldimines in high yields. This is an efficient, atom-economic, and green method.
- Yu, Xufen,Lu, Xiyan
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scheme or table
p. 2076 - 2079
(2011/05/09)
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- New cyclopalladated benzothiophenes: A catalyst precursor for the Suzuki coupling of deactivated aryl chlorides
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Dimeric benzothiophene-based palladacycles were synthesized from thioanisole-substituted perfluoroalkyl propargyl imines and palladium(ii) salts via an intramolecular thiopalladation pathway. The treatment of benzothiophene-based palladacycles with an exc
- Subhas, Madavu Salian,Racharlawar, Shailesh S.,Sridhar,Kennady, P. Kavin,Likhar, Pravin R.,Kantam, Mannepalli Lakshmi,Bhargava, Suresh K.
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experimental part
p. 3001 - 3006
(2010/09/06)
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- A functionalized phosphine ligand with a pentaarylbenzene moiety in palladium-catalyzed Suzuki-Miyaura coupling of aryl chlorides
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A functionalized phosphine with a pentaarylbenzene moiety was found to facilitate the palladium-catalyzed Suzuki-Miyaura coupling of aryl chlorides. The new ligand achieved high turnover numbers (up to TON 5000).
- Iwasawa, Tetsuo,Kamei, Toshinori,Watanabe, Satoshi,Nishiuchi, Masaki,Kawamura, Yasuhiko
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supporting information; experimental part
p. 7430 - 7433
(2009/05/11)
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- Achieving conformational control over C-C, C-N and C-O bonds in biaryls, N,N′-diarylureas and diaryl ethers: Advantages of a relay axis
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The orientation of Ar-C, Ar-N and Ar-O bonds in biaryls, N,N′-diarylureas and diaryl ethers (whose conformers are distinguishable by NMR) may be controlled with a selectivity up to >95: 5 by an adjacent stereogenic centre; the selectivity may be greater when a second stereogenic axis is inserted between the controlling centre and the slowly rotating bond. The Royal Society of Chemistry.
- Betson, Mark S.,Bracegirdle, Ann,Clayden, Jonathan,Helliwell, Madeleine,Lund, Andrew,Pickworth, Mark,Snape, Timothy J.,Worrall, Christopher P.
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p. 754 - 756
(2007/10/03)
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- Synthesis of substituted phenanthrenes via intramolecular condensation based on temperature-dependent deprotonation using a weak carbonate base
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Construction of substituted phenanthrenes via intramolecular condensation of 2′-methylbiphenyl-2-carbaldehydes using a mild base at 200 °C is described. The required high temperature can be quickly reached and easily maintained using microwave flash heating. Georg Thieme Verlag Stuttgart.
- Monsieurs, Katrien,Rombouts, Geert,Tapolcsányi, Pál,Mátyus, Péter,Maes, Bert U. W.
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p. 3225 - 3230
(2008/09/17)
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- Flow-vacuum pyrolysis of polycyclic compounds. 221 : Pyrolysis of 2,2'-bis(hydroxymethyl)biphenyl
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The flow-vacuum pyrolysis of the title diol, between 600°C - 800°C and 1mm Hg in argon atmosphere, was investigated using GC/MS. The main reaction products were: fluorene, 9-methylfluorene, 9-methylenefluorene; 9,10-dihydrophenanthrene; phenanthrene; 9-hydroxy-9,10-dihydroanthracene; 9-fluorenol; 9-fluorenone; 2-methyl-2'-formylbiphenyl (major product; 38% at 850°C); 2-hydroxymethyl-2'-formylbiphenyl and 2,2'-diphendialdehyde. The amount of products resulted from intramolecular cyclization was 52% at 850°C and the ratio between products with five-member and six-member central ring was 39:13 at 850°C. A radical mechanism explaining the formation of the reaction products is suggested and a comparison between pyrolysis of the title diol and of the previously studied 2,2'-bis(bromomethyl)biphenyl is made.
- Istrati, Daniela,Marton, George,Drǎghici, Constantin,Grigore, Adriana,Banciu, Mircea D.
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p. 719 - 724
(2007/10/03)
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- An active ferrocenyl triarylphosphine for palladium-catalyzed Suzuki-Miyaura cross-coupling of aryl halides
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Pd-catalyzed Suzuki-Miyaura reaction of aryl chlorides was accomplished through the use of an active ferrocene-based triarylphosphine ligand. This air- and moisture-stable ligand was found to be effective for the cross-coupling of aryl halides at room temperature to 115 °C.
- Kwong, Fuk Yee,Chan, Kin Shing,Yeung, Chi Hung,Chan, Albert S. C.
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p. 2336 - 2337
(2007/10/03)
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- The first general palladium catalyst for the Suzuki-Miyaura and carbonyl enolate coupling of aryl arenesulfonates
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The first general method for the palladium-catalyzed Suzuki-Miyaura and carbonyl enolate coupling of unactivated aryl arenesulfonates was developed utilizing XPhos, 1, and Pd(OAc)2. This is of significant interest because aryl tosylates and aryl benzenesulfonates are more easily handled and considerably less expensive than aryl triflates. This catalyst system effects the coupling of a variety of aryl, heteroaryl, and extremely hindered arylboronic acids with different aryl tosylates, under mild conditions. The same catalyst was employed in the first carbonyl enolate coupling of aryl arensulfonates. Copyright
- Nguyen, Hanh Nho,Huang, Xiaohua,Buchwald, Stephen L.
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p. 11818 - 11819
(2007/10/03)
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- Palladium-catalyzed Suzuki-Miyaura cross-coupling reactions of potassium aryl- and heteroaryltrifluoroborates
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An extended study of the reactivity of potassium aryl- and heteroaryltrifluoroborates in Suzuki-Miyaura cross-coupling reactions is presented. The coupling of aryl- and electron-rich heteroaryltrifluoroborates with aryl and activated heteroaryl bromides proceeds readily under ligandless conditions. When deactivated aryl- and heteroaryltrifluoroborates are coupled with aryl and heteroaryl bromides and chlorides, a low loading (0.5-2%) of PdCl2(dppf)·CH2Cl2 efficiently catalyzes the reactions. Under either condition, reactions can generally be carried out in an open atmosphere.
- Molander, Gary A.,Biolatto, Betina
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p. 4302 - 4314
(2007/10/03)
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- Efficient Ligandless Palladium-Catalyzed Suzuki Reactions of Potassium Aryltrifluoroborates
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R1BF3K + R2X Pd(OAc) 2 (0.5% mol)→ R1-R2 K2CO 3 (3 equiv) methanol, reflux R1 = aryl or heteroaryl R2 = aryl or heteroaryl X = halide, triflate The ligandless palladium-catalyzed Suzuki cross-coupling reaction of potassium aryl- and heteroaryltrifluoroborates with aryl- or heteroaryl halides or triflates proceeds readily with very good yields. The cross coupling can be effected in methanol or water, in the open air, using Pd(OAc)2 as a catalyst in the presence of K2CO3. A variety of functional groups are tolerated.
- Molander, Gary A.,Biolatto, Betina
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p. 1867 - 1870
(2007/10/03)
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- Triaromatic compounds and pharmaceutical/cosmetic compositions comprised thereof
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Novel pharmaceutically/cosmetically-active triaromatic compounds have the structural formula (I): and are useful for the treatment of a wide variety of disease states, whether human or veterinary, for example dermatological, rheumatic, respiratory, cardiovascular, bone and ophthalmological disorders, as well as for the treatment of mammalian skin and hair conditions/disorders.
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- Manganese-catalyzed substitution of activated aryl halides (X = Cl, Br and F) and aryl ethers by organomagnesium reagents
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In the presence of manganese chloride (10%), Grignard reagents readily react in THF with aryl bromides, chlorides and even fluorides, as well as aryl methyl ethers bearing in the ortho- or para-position an electron withdrawing activating group (CN, CH=NR, oxazoline). Aryl and N- or S- alkylmagnesium halides have been used successfully. The reaction is performed under mild conditions (0 °C to room temperature, 30 minutes to 24 hours) and leads to cross-coupling products in good yields.
- Cahiez, Gerard,Lepifre, Franck,Ramiandrasoa, Parfait
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p. 2138 - 2144
(2007/10/03)
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- Reactions of Diene-conjugated 1,3-Dipolar Intermediates: A Versatile and Efficient Route to Dibenzazepines via Benzonitrile o-Arylbenzyl Ylides
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Diene-conjugated nitrile ylides of the type 1 in which both the α,β- and the γ,δ-double bonds are aromatic and where R is either hydroger or a para substitutent, cyclise to give dibenzazepines21 (Scheme 2) in high yield.This is in contrast to the analogous diazo system 2 in which cyclisation do not occur.The presence of an ortho methyl group in the ring under attack (1j, Scheme 3) prevents cyclisation via its steric limitations of conjugation in the transition state.
- Cullen, Kevin E.,Sharp, John T.
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p. 2961 - 2968
(2007/10/02)
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