- Efficient Cu-catalyzed intramolecular: O -arylation for synthesis of benzoxazoles in water
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An efficient method was developed for synthesis of benzoxazoles by Cu-catalyzed intramolecular O-arylation of o-halobenzanilides in water. This strategy provides several advantages, such as high yields, water as a green solvent and functional groups tolerance.
- Gao, Hui,Li, Minxin,Mao, Zewei,Rao, Gaoxiong,Tang, Yanling
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p. 14317 - 14321
(2020/04/23)
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- Phosphine-phosphonium ylides as ligands in palladium-catalysed C2-H arylation of benzoxazoles
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As balanced electron-rich P,C-chelating ligands, phosphine-phosphonium-ylides are considered for their ability to in situ promote palladium-catalysed direct C(sp2)–H arylation. Using methyl phosphonium salts of 2,2'-bis(diphenylphosphino)-1,1'-binaphtyl (“methyl-BINAPIUM”) as ylide precursors under optimized reaction conditions, arylation of benzoxazole was found to proceed in moderate to high yield to give functional 2-aryl benzoxazoles. A strong anion effect of the non-salt free ylide was evidenced (TfO? > I? > PF6? ≈ salt-free). This first example of phosphonium ylides as ligands in catalytic C–H activation extends the prospect of their general implementation in homogeneous transition metal catalysis.
- Yao, Zhenyu,Lin, Xing,Chauvin, Remi,Wang, Lianhui,Gras, Emmanuel,Cui, Xiuling
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p. 3250 - 3254
(2020/05/25)
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- Synthesis of Benz-Fused Azoles via C-Heteroatom Coupling Reactions Catalyzed by Cu(I) in the Presence of Glycosyltriazole Ligands
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Glycosyl triazoles are conveniently accessible and contain multiple metal-binding units that may assist in metal-mediated catalysis. Azide derivatives of d-glucose have been converted to their respective aryltriazoles and screened as ligands for the synthesis of 2-substituted benz-fused azoles and benzimidazoquinazolinones by Cu-catalyzed intramolecular Ullmann type C-heteroatom coupling. Good to excellent yields for a variety of benz-fused heterocyles were obtained for this readily accessible catalytic system.
- Mishra, Nidhi,Singh, Anoop S.,Agrahari, Anand K.,Singh, Sumit K.,Singh, Mala,Tiwari, Vinod K.
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supporting information
p. 389 - 399
(2019/05/06)
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- Iron-Catalyzed Sulfur-Promoted Decyanative Redox Condensation of o-Nitrophenols and Arylacetonitriles: An Unprecedented Route to 2-Arylbenzoxazoles
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Elemental sulfur in the presence of a catalytic amount of FeCl2·4H2O was found to be highly efficient for the promotion of decyanative redox condensation reactions of o-nitrophenols with arylacetonitriles, to give a wide range of 2-arylbenzoxazoles. The utility of elemental sulfur was highlighted by its role as cyanide scavenger and external reducing agent.
- Nguyen, Thanh Binh,Lung, Jerome Cheung
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supporting information
p. 5815 - 5818
(2018/11/24)
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- Nickel-Catalyzed Coupling of Azoles with Aromatic Nitriles
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This manuscript describes the Ni-catalyzed coupling of azoles with aromatic nitriles. The use of BPh3 promotes these arylations with electronically diverse azoles and benzonitriles. While the nickel catalyst is necessary for the arylations of phenyl oxazoles, arylation of benzoxazoles with some nitriles affords the arylated products even in the absence of the Ni catalyst albeit in lower yield than the catalyzed process. The Ni-catalyzed process exhibits higher rates and a broader scope than the uncatalyzed transformation.
- Hanson, McKenna G.,Olson, Noelle M.,Yi, Zubaoyi,Wilson, Grace,Kalyani, Dipannita
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supporting information
p. 4271 - 4274
(2017/08/23)
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- Room-temperature palladium-catalyzed direct 2-arylation of benzoxazoles with aryl and heteroaryl bromides
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An efficient room-temperature palladium-catalyzed direct 2-arylation of benzoxazoles with aryl bromides is presented. The Pd(OAc)2/ NiXantphos-based catalyst enables the introduction of various aryl and heteroaryl groups, via a deprotonative cross-coupling process (DCCP) in good to excellent yields (60-99%). This journal is the Partner Organisations 2014.
- Gao, Feng,Kim, Byeong-Seon,Walsh, Patrick J.
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supporting information
p. 10661 - 10664
(2014/10/15)
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- Base-promoted formal arylation of benzo[d]oxazoles with acyl chloride
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A base-promoted formal arylation of benzo[d]oxazoles with acyl chloride was achieved in moderate to good yields. This reaction was triggered by the N-acylation of oxazole to form an iminium intermediate. Then, the addition of H2O to the iminium formed the hemiacetal intermediate. After the sequential ring-opening, extrusion of CO, the ring closure, the dehydration delivered the formal arylation product. In comparison with the transition-metal-catalyzed methodology, it represents an alternative arylation method leading to 2-arylbenzooxazole.
- Wang, Lei,Ren, Xinyi,Yu, Jintao,Jiang, Yan,Cheng, Jiang
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p. 12076 - 12081
(2014/01/06)
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- Palladium-catalyzed desulfitative arylation of azoles with arylsulfonyl hydrazides
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Palladium-catalyzed desulfitative and denitrogenative arylation of azoles with arylsulfonyl hydrazides has been achieved. A broad scope of azoles and arylsulfonyl hydrazides has been used to produce arylated azoles in high yields.
- Yu, Xinzhang,Li, Xingwei,Wan, Boshun
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p. 7479 - 7482
(2012/10/29)
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- Pd(OAc)2 catalyzed synthesis of 2-aryl- and 2-heteroaryl- benzoxazoles and benzothiazoles in imidazolium ionic liquids (ILs) without additives and with recycling/reuse of the IL
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A facile, high yielding, method for the synthesis of a library of 2-aryl- and 2-heteroaryl-benzoxazoles and benzothiazoles from readily available Schiff bases is reported employing catalytic amounts of Pd(OAc)2 in imidazolium ionic liquids (bmim)BF4 and (bmim)PF6 without ligands and/or additives. Simple product isolation and recycling/re-use of the IL are additional advantages of this method.
- Kalkhambkar, Rajesh G.,Laali, Kenneth K.
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supporting information; experimental part
p. 4212 - 4215
(2012/08/28)
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- Palladium-catalyzed direct arylations of heteroarenes with tosylates and mesylates
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(Chemical Equation Presented) A toss up: A highly active palladium complex enabled the first direct arylation of heteroarenes through C-H bond functionalization using tosylates or mesylates as electrophiles with ample scope.
- Ackermann, Lutz,Althammer, Andreas,Fenner, Sabine
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supporting information; experimental part
p. 201 - 204
(2009/04/10)
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- Biochemical and structural evaluation of highly selective 2-arylbenzoxazole-based transthyretin amyloidogenesis inhibitors
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To develop potent transthyretin (TTR) amyloidogenesis inhibitors that also display high binding selectivity in blood, it proves useful to systematically optimize each of the three substructural elements that comprise a typical inhibitor: the two aryl rings and the linker joining them. In the first study, described herein, structural modifications to one aryl ring were evaluated by screening a library of 2-arylbenzoxazoles bearing thyroid hormone-like aryl substituents on the 2-aryl ring. Several potent and highly selective amyloidogenesis inhibitors were identified that exhibit minimal thyroid hormone nuclear receptor and COX-1 binding. High resolution crystal structures (1.3-1.5 ?) of three inhibitors (2f, 4f, and 4d) in complex with TTR were obtained to characterize their binding orientation. Collectively, the results demonstrate that thyroid hormone-like substitution patterns on one aryl ring lead to potent and highly selective TTR amyloidogenesis inhibitors that lack undesirable thyroid hormone receptor or COX-1 binding.
- Johnson, Steven M.,Connelly, Stephen,Wilson, Ian A.,Kelly, Jeffery W.
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p. 260 - 270
(2008/09/18)
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