- Immobilized Carbodiimide Assisted Flow Combinatorial Protocol to Facilitate Amide Coupling and Lactamization
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Through a screen of over one hundred and 30 permutations of reaction temperatures, solvents, carbodiimide resins, and carbodiimide molar equivalences, in the presence, absence, or combination of diisopropylamine and benzotriazole additives, a convenient and first reported carbodiimide polymer-assisted flow approach to effect amide coupling and lactamization was developed. The protocol entails injecting a single solution (1:9 dimethylformamide: dichloromethane) containing a carboxylic acid and an amine or linear peptide sequence into a continuous stream of dichloromethane. The protocol remained viable in the absence of base, did not require carboxylate preactivation which, and in concert with minimal workup requirements, enabled the isolation of products in high yields. Compared to the utilization of untethered carbodiimide reagents, the flow procedure was also observed to provide a degree of racemization safety.
- Aldrich-Wright, Janice R.,Dankers, Christian,Gordon, Christopher P.,Harman, David G.,Nguyen, Thanh V.,Tadros, Joseph
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supporting information
p. 255 - 267
(2020/06/05)
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- Pd-catalyzed chemoselective carbonylation of aminophenols with iodoarenes: Alkoxycarbonylation vs aminocarbonylation
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Palladium-catalyzed chemoselective carbonylation of aminophenols with iodoarenes was realized by changing ligand and base. 3- or 4-Aminophenols afforded esters in high yields and selectivities using 1,3-bis(diphenylphosphino)propane as the ligand and K2CO3 as the base, and gave amides in high yields and selectivities using 1,3-bis(diisobutylphosphino)propane as the ligand and DBU as the base. 2-Aminophenol only gave amides in high yields under both conditions.
- Xu, Tongyu,Alper, Howard
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supporting information
p. 16970 - 16973
(2015/02/02)
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- Synthesis, antimicrobial, and QSAR studies of substituted benzamides
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A series of new substituted benzamides were synthesized and tested in vitro for their antibacterial activity against Gram-positive and Gram-negative bacteria and as well for antifungal activity. The compounds 8i and 9 showed better activity among the different benzamides synthesized. The structural characteristics governing antibacterial activities of substituted benzamides were studied using QSAR methodology. The results showed that the antimicrobial activity could be modeled using the topological descriptors, molecular connectivity indices (2χv and 2χ) and Kiers shape index (κα1). The low residual activity and high cross-validated r2 values (rcv2) observed indicated the predictive ability of the developed QSAR models.
- Kumar, Anil,Narasimhan, Balasubramanian,Kumar, Devinder
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p. 4113 - 4124
(2008/03/11)
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- Smart cleavage reactions: The synthesis of benzimidazoles and benzothiazoles from polymer-bound esters
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The preparation of an array of benzimidazoles and benzothiazoles from polymer-bound esters is described. Polymer-bound esters were treated with 2-aminothiophenols or 1,2-phenylenediamines in the presence of a Lewis acid to afford the corresponding benzothiazole or benzimidazole cleavage products. The reaction of 2-aminophenols with the polymer-bound esters failed to give the desired benzoxazole products using this procedure.
- Matsushita, Hana,Lee, Sang-Hyeup,Joung, Meyoungju,Clapham, Bruce,Janda, Kim D.
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p. 313 - 316
(2007/10/03)
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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 and microbiological activity of some N-(o-hydroxyphenyl)benzamides and phenylacetamides as the possible metabolites of antimicrobial active benzoxazoles: Part II
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The synthesis of some N-(o-hydroxyphenyl)benzamides and benzacetamides (2a-2p) in order to determine their in vitro antimicrobial activity against two Gram-positive bacteria, three Gram-negative bacteria and the fungus Candida albicans is described. The new compounds were compared with several control drugs. The derivative 2g, 4-amino-N-(o-hydroxyphenyl)benzamide, was found active at an MIC value of 25 μg/ml against the Gram-negative microorganism Klebsiella pneumoniae. Most of the compounds exhibited antibacterial activity at an MIC value of 25 μg/ml against Pseudomonas aureginosa. For the antifungal activity against C. albicans, compounds 2e, 2h and 2m were found more active than the other derivatives (MIC 12.5 μg/ml). The antimicrobial activity of some of these benzamide and phenylacetamide derivatives (2a, 2b, 2f, 2g, 2h and 2k), possible metabolites of benzoxazoles, was also compared with that of the cyclic analogues 3-8. Compound 2f possesses two dilutions better antifungal activity than its cyclic analogue the benzoxazole derivative 5 against C. albicans, while having one dilution better antibacterial activity against Streptococcus faecalis and K. pneumoniae. (C) 2000 Elsevier Science S.A.
- Sener, Esin Aki,Bingoel, Kamuran K.,Oeren, Ilkay,Arpaci, Oezlem Temiz,Yalcin, Ismail,Altanlar, Nurten
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p. 469 - 476
(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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- Photolysis of 2-Nitrophenyl Benzyl Ethers in Neutral and Acidic Media
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2-Nitrophenyl benzyl ethers (1a-d) on irradiation afford N-benzoyl-2-aminophenols (4) as the major products.The other minor products are 2-nitrophenol (2), 4-benzyl-2-nitrophenol (3), 2-phenylbenzoxazoles (5) and 2-nitrophenyl benzoate (6).A plausible mechanism to account for the formation of various products is discussed.
- Jacob E. Dominic,Joshua, C. P.
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p. 808 - 810
(2007/10/02)
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- Eine einfache Methode zur Herstellung von Benzoxazolen
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The preparation of benzoxazoles by a facile one-pot reaction is reported.The reaction of carboxylic acids with 2-chloro-N-methyl-Δ1-pyrrolinium chloride in an excess of N-methyl-2-pyrrolidone afforded carboxylic acid chlorides which were converted subsequently to their 2-hydroxyanilides by addition of 2-aminophenols.Cyclization of the 2-hydroxy-anilides at elevated temperatures furnished the benzoxazoles in high yield and purity.
- Seha, Zdenek,Weis, Claus D
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p. 413 - 419
(2007/10/02)
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