- Synthesis of β-Hydroxy α-Amino Acids through Br?nsted Base-Catalyzed syn-Selective Direct Aldol Reaction of Schiff Bases of Glycine o-Nitroanilide
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Here we report the highly enantio- and syn-selective synthesis of β-hydroxy α-amino acids from glycine imine derivatives under Br?nsted base (BB) catalysis. The key of this approach is the use of benzophenone-derived imine of glycine o-nitroanilide as a pronucleophile, where the o-nitroanilide framework provides an efficient hydrogen-bonding platform that accounts for nucleophile reactivity and diastereoselectivity.
- Vera, Silvia,Vázquez, Ana,Rodriguez, Ricardo,Pozo, Sandra Del,Urruzuno, I?aki,de Cózar, Abel,Mielgo, Antonia,Palomo, Claudio
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p. 7757 - 7772
(2021/06/21)
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- Palladium-Catalyzed Synthesis of Aryl Amides through Silanoate-Mediated Hydrolysis of Nitriles
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A procedure for the formation of aryl amides through the palladium-catalyzed coupling of nitriles and aryl bromides, via the formation of intermediary silanoate derived imidate species is reported. Optimization was undertaken and examples of the process are described that furnish the products in up to 86% isolated yield.
- McPherson, Christopher G.,Livingstone, Keith,Jamieson, Craig,Simpson, Iain
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supporting information
p. 88 - 92
(2015/12/26)
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- N, N -diethylurea-catalyzed amidation between electron-deficient aryl azides and phenylacetaldehydes
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Urea structures, of which N,N-diethylurea (DEU) proved to be the most efficient, were discovered to catalyze amidation reactions between electron-deficient aryl azides and phenylacetaldehydes. Experimental data support 1,3-dipolar cycloaddition between DEU-activated enols and electrophilic phenyl azides, especially perfluoroaryl azides, followed by rearrangement of the triazoline intermediate. The activation of the aldehyde under near-neutral conditions was of special importance in inhibiting dehydration/aromatization of the triazoline intermediate, thus promoting the rearrangement to form aryl amides.
- Xie, Sheng,Ramstr??m, Olof,Yan, Mingdi
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p. 636 - 639
(2015/03/04)
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- Synthesis of benzimidazoles by phosphine-mediated reductive cyclisation of ortho-nitro-anilides
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Heating ortho-nitro-anilides 1-3 and 2-methyl-N-(3-nitropyridin-2-yl) propanamide (5) with 4 equiv. of a phosphine led to the 2-substituted benzimidazoles 6-8 and to the imidazo[4,5-b]pyridine 10, respectively, in yields between 45 and 85%. Heating 1 with (EtO)3P effected cyclisation and N-ethylation, leading to the 1-ethylbenzimidazole 6b. The slow cyclisation of the N-pivaloylnitroaniline 2b allowed isolation of the intermediate phosphine imide 11 that slowly transformed into the 1H-benzimidazole 7b. The structure of 11 was established by crystal-structure analysis. While the N-methylated ortho-nitroacetanilide 3 cyclised to the 1,2-dimethyl-1H-benzimidazole (8), the 2-methylpropananilide 4 was transformed into 1-methyl-3-(1-methylethyl)-2H- benzimidazol-2-one (9).
- Duchek, Jan,Vasella, Andrea
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experimental part
p. 977 - 986
(2011/08/05)
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- On the active site for hydrolysis of aryl amides and choline esters by human cholinesterases
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Cholinesterases, in addition to their well-known esterase action, also show an aryl acylamidase (AAA) activity whereby they catalyze the hydrolysis of amides of certain aromatic amines. The biological function of this catalysis is not known. Furthermore, it is not known whether the esterase catalytic site is involved in the AAA activity of cholinesterases. It has been speculated that the AAA activity, especially that of butyrylcholinesterase (BuChE), may be important in the development of the nervous system and in pathological processes such as formation of neuritic plaques in Alzheimer's disease (AD). The substrate generally used to study the AAA activity of cholinesterases is N-(2-nitrophenyl)acetamide. However, use of this substrate requires high concentrations of enzyme and substrate, and prolonged periods of incubation at elevated temperature. As a consequence, difficulties in performing kinetic analysis of AAA activity associated with cholinesterases have hampered understanding this activity. Because of its potential biological importance, we sought to develop a more efficient and specific substrate for use in studying the AAA activity associated with BuChE, and for exploring the catalytic site for this hydrolysis. Here, we describe the structure-activity relationships for hydrolysis of anilides by cholinesterases. These studies led to a substrate, N-(2-nitrophenyl)trifluoroacetamide, that was hydrolyzed several orders of magnitude faster than N-(2-nitrophenyl)acetamide by cholinesterases. Also, larger N-(2-nitrophenyl)alkylamides were found to be more rapidly hydrolyzed by BuChE than N-(2-nitrophenyl)acetamide and, in addition, were more specific for hydrolysis by BuChE. Thus, N-(2-nitrophenyl)alkylamides with six to eight carbon atoms in the acyl group represent suitable specific substrates to investigate further the function of the AAA activity of BuChE. Based on the substrate structure-activity relationships and kinetic studies, the hydrolysis of anilides and esters of choline appears to utilize the same catalytic site in BuChE.
- Darvesh, Sultan,McDonald, Robert S.,Darvesh, Katherine V.,Mataija, Diane,Mothana, Sam,Cook, Holly,Carneiro, Karina M.,Richard, Nicole,Walsh, Ryan,Martin, Earl
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p. 4586 - 4599
(2007/10/03)
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- Nonpeptide inhibitors of measles virus entry
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Measles virus (MV) is one of the most infectious pathogens known. Despite the existence of a vaccine, over 500 000 deaths/year result from MV or associated complications. Anti-measles compounds could conceivably reverse these statistics. Previously, we described a homology model of the MV fusion protein trimer and a putative binding site near the head-neck region. The resulting model permitted the identification of two nonpeptidic entry inhibitors. Here, we present the design, synthesis, and bioevaluation of several series of fusion inhibitors and describe their structure-activity relationships (SAR). Five simply substituted anilides show low-μM blockade of the MV, one of which (AS-48) exhibits IC50 = 0.6-3.0 μM across a panel of wild-type MV strains found in the field. Molecular field topology analysis (MFTA), a 2D QSAR approach based on local molecular properties (atomic charges, hydrogen-bonding capacity and local lipophilicity), applied to the anilide series suggests structural modifications to improve potency.
- Sun, Aiming,Prussia, Andrew,Zhan, Weiqiang,Murray, Ernest E.,Doyle, Joshua,Cheng, Li-Ting,Yoon, Jeong-Joong,Radchenko, Eugene V.,Palyulin, Vladimir A.,Compans, Richard W.,Liotta, Dennis C.,Plemper, Richard K.,Snyder, James P.
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p. 5080 - 5092
(2007/10/03)
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- A mild and efficient procedure for the conversion of aromatic carboxylic esters to secondary amides
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A mild and efficient procedure has been developed for the conversion of aromatic carboxylic esters to secondary amides using reusable Zn dust with microwave heating in the presence of N,N-dimethylformamide or conventional heating by stirring in an oil bath using THF as solvent. Zn dust can be reused several times after simple washing with dil. HC1 and distilled water.
- Arora, Revika,Paul, Satya,Gupta, Rajive
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p. 1137 - 1140
(2007/10/03)
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