- Iron(III) Chloride Mediated para-Selective C-H Functionalization: Access to C5-Chloro and C5,C7-Dichloro/Dianisyl Substituted 2-Arylbenzoxazoles
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Iron(III) chloride mediated para-selective C?H chlorination and subsequent annulation of 2-amidophenol to synthesize C5- and C5, C7-chlorinated benzoxazoles was developed. Further, the oxidative cross-dehydrogenative coupling of amidophenol with anisole b
- Panda, Niranjan,Sahoo, Kanchanbala
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supporting information
(2022/02/03)
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- Multicomponent Synthesis of Isoindolinone Frameworks via RhIII-Catalysed in situ Directing Group-Assisted Tandem Oxidative Olefination/Michael Addition
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A RhIII-catalysed three-component synthesis of isoindolinone frameworks via direct assembly of benzoyl chlorides, o-aminophenols and activated alkenes has been developed. The process involves in situ generation of o-aminophenol (OAP)-based bidentate directing group (DG), RhIII-catalysed tandem ortho C?H olefination and subsequent cyclization via aza-Michael addition. This protocol exhibits good chemoselectivity and functional group tolerance. Computational studies showed that the presence of hydroxyl group on the N-aryl ring could enhance the chemoselectivity of the reaction.
- Wang, Liang,Liu, Xi,Liu, Jian-Biao,Shen, Jun,Chen, Qun,He, Ming-Yang
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supporting information
p. 765 - 769
(2018/03/07)
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- Divergent reactivities of o-haloanilides with CuO nanoparticles in water: A green synthesis of benzoxazoles and o-hydroxyanilides
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In the present study, three divergent reaction paths emerged when o-haloanilides were subjected to CuO nanoparticles in water. o-Halo (I, Br) phenylbenzamides in the presence of CuO nanoparticles and Cs2CO 3 in water at 100 °C provided o-hydroxyphenyl benzamides as the major product. However, a complete change in selectivity was observed in the presence of an organic base/ligand (TMEDA), giving 2-arylbenzoxazole as the exclusive product. The above selectivities were not clearly distinct when the corresponding alkylamides were treated either in the presence or absence of the ligand. A number of o-halophenyl alkylamides provided either exclusively o-dehalogenated products or a mixture of o-dehalogenated and o-hydroxylated products, but none gave 2-alkylbenzoxazoles. In addition to the above selectivities, the use of an environmentally friendly solvent (water) and base, and the recyclability of the catalyst make this procedure a benign alternative to the existing methods for the synthesis of these molecules, viz. o-hydroxybenzamides and o-arylbenzoxazoles.
- Khatun, Nilufa,Guin, Srimanta,Rout, Saroj Kumar,Patel, Bhisma K.
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p. 10770 - 10778
(2014/03/21)
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- A microwave assisted synthesis of benzoxazoles from carboxylic acids
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A series of various poly-substituted benzoxazoles were synthesized starting from readily available carboxylic acids. The method is based on TCT (cyanuric chloride)/microwave acid activation and it is characterized by mild conditions, allowing for a wide range of starting materials and functionalization of final products.
- Nieddu, Giammario,Giacomelli, Giampaolo
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p. 791 - 795
(2013/07/25)
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- N-(2-hydroxyaryl)benzamide synthesis from 2-nitroaryl benzoates via an Indium-mediated reduction-migration reaction
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A one-pot reduction-triggered N-(2-hydroxyaryl)benzamide synthesis from 2-nitroaryl benzoate substrates was investigated. In the presence of indium/AcOH in THF/H2O, 2-nitroaryl benzoates produced reasonable yields of the benzo group migrated N-
- Lee, Hyejeong,Kim, Minki,Jun, Young Moo,Kim, Byeong Hyo,Lee, Byung Min
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p. 158 - 167
(2011/10/08)
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- A one-pot, two-step microwave-assisted synthesis of highly functionalized benzoxazoles using solid-supported reagents (SSRs)
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A one-pot, two-step protocol for the microwave-assisted solid-phase synthesis of substituted benzoxazoles has been developed starting from different polymer-bound esters we previously designed as solid-supported reagents (SSRs) for the acylation of amines, alcohols and phenols. The combination of a parallel synthesizer and a microwave reactor allowed to quickly prepare a collection of substituted benzoxaxoles in high purity and satisfactory yields. This protocol is amenable for automation and could be used for the preparation of combinatorial libraries in drug discovery programs.
- Radi, Marco,Saletti, Sara,Botta, Maurizio
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p. 4464 - 4466
(2008/09/21)
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- Hypervalent iodine in synthesis 69: An efficient synthesis of 2-arylbenzoxazoles via the palladium-catalysed carbonylation and condensation of diaryliodonium salts and o-aminophenols
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An efficient synthetic method is reported in which 2-arylbenzoxazoles have been prepared in good to excellent yields under mild reaction conditions by the palladium-catalysed carbonylation of diaryliodonium salts with o-aminophenols followed by dehydrative cyclisation.
- Zhou,Chen
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p. 235 - 237
(2007/10/03)
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- Synthesis of 2-Arylbenzoxazoles via the Palladium-Catalyzed Carbonylation and Condensation of Aromatic Halides and o-Aminophenols
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A new synthetic method is reported in which 2-arylbenzoxazoles can be prepared by palladium-catalyzed condensation of aryl halides with o-aminophenols followed by dehydrative cyclization.This method is tolerant of a wide variety of functional groups on either aromatic ring and gives good to excellent yields of products.An aliphatic vicinal amino alcohol gave a bis-acylated product as well as a chlorine-containing product with only a small amount of the desired 2-aryloxazole being formed.Methyl iodide and benzyl bromide gave only alkylated products.
- Perry, Robert J.,Wilson, B. David,Miller, Richard J.
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p. 2883 - 2887
(2007/10/02)
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- Tertiary Amine-Catalyzed Acyl Group Exchange Reaction of N,O-Diacyl-o-aminophenols. Its Mechanism and Factors Determining the Relative Stability of Acyl Exchanged Isomer Pairs
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Acyl substituent effects on the equilibrium and rate constants for the acyl group exchange reactions of various N,O-diacyl-o-aminophenols have been investigated in solvents with different polarities.It was found that the relative stability of acyl exchanged isomer pairs is determined solely by the inductive effect of acyl groups, provided that the steric hindrance of acyl substituents bonded to amide nitrogen affects the stability to the same extent.The importance of steric hindrance exerted by a bulky acyl group in determining the relative stability was demonstrated by analyzing the correlation between the standard free energy change (ΔG0) and pKa, which were used as the measure of the relative stability of isomer pairs and of the electron-with drawing ability of acyl groups, respectively.On the other hand, the logarithms of catalytic rate constants for the acyl migration reactions were correlated well to the pKa values.In addition to this finding, a large negative value of activation entropy (ΔS=-160 J K-1 mol-1) and the Broensted coefficient β of 0.65 for the reaction of N,O-(acetyl)-(1-naphthoyl) pair of N,O-diacyl-o-aminophenol provide a definitive evidence for the rate-determining proton transfer from this derivative to amine catalyst in the transition state.
- Sakurai, Tadamitsu,Kojima, Shuichi,Inoue, Hiroyasu
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p. 3141 - 3148
(2007/10/02)
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