- Stereoretentive N-Arylation of Amino Acid Esters with Cyclohexanones Utilizing a Continuous-Flow System
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The N-arylation of chiral amino acid esters with minimal racemization is a challenging transformation because of the sensitivity of the α-stereocenter. A versatile synthetic method was developed to prepare N-arylated amino acid esters using cyclohexanones as aryl sources under continuous-flow conditions. The designed flow system, which consists of a coil reactor and a packed-bed reactor containing a Pd(OH)2/C catalyst, efficiently afforded the desired N-arylated amino acids without significant racemization, accompanied by only small amounts of easily removable co-products (i. e., H2O and alkanes). The efficiency and robustness of this method allowed for the continuous synthesis of the desired product in very high yield and enantiopurity with high space-time yield (74.1 g L?1 h?1) and turnover frequency (5.9 h?1) for at least 3 days.
- Ichitsuka, Tomohiro,Komatsuzaki, Shingo,Masuda, Koichiro,Koumura, Nagatoshi,Sato, Kazuhiko,Kobayashi, Shū
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supporting information
p. 10844 - 10848
(2021/05/31)
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- Stereospecific Synthesis of 3,4-Dihydro-2 H-naphtho-1,4-oxazin-2-ones by Unification of Benzoxepine-4-carboxylates with Chiral Amino Acid Ethyl Esters
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A novel and efficient stereocontrolled method has been developed for the preparation of chiral 3,4-dihydro-2H-naphtho[1,2-b][1,4]oxazin-2-ones by the reaction of benzoxepine-4-carboxylates with chiral amino acid ethyl esters for the first time. The chiral 3,4-dihydro-2H-naphtho-1,4-oxazinones have been achieved in one step by the formation of C-N, C-C, and C-O bonds.
- Bhimapaka, China Raju,Kasagani, Veera Prasad,Kurma, Siva Hariprasad
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supporting information
p. 2976 - 2983
(2020/03/23)
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- Chiral 3 - morpholine methyl alcohol and 3 - morpholine a acid preparation method of the compound
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The invention discloses a novel method for preparing chiral 3-morpholine methanol and 3-morpholine formic acid compounds. The method comprises the following steps: taking chiral serine as an initial material to obtain a serine ester (III) from a catalyst by esterification; reacting with halogen acetyl halide under an alkaline condition to obtain a compound (IV); obtaining a compound (V) by hydroxyl protection; adding a reducing agent to restore the ester into alcohol (VI); carrying out cyclization under the alkaline condition to obtain a compound (VII); obtaining a target product chiral 3-morpholine methanol compound (I) by amide reduction, hydroxyl deprotection and N protection; obtaining a chiral 3-morpholine formic acid compound (II) by oxidation. The method has the advantages of being low in cost, friendly to environment, simple to operate, high in yield, high in product purity and the like, the used reagent is simple and safe, and an intermediate in the reaction of each step does not need to be further purified, so that the experiment operation is greatly simplified, the production cost is reduced, and the method is applicable to industrial production.
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Paragraph 0043-0045
(2018/11/04)
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- Design, synthesis, and biological evaluation of amide imidazole derivatives as novel metabolic enzyme CYP26A1 inhibitors
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All-trans-retinoic acid (ATRA) as a physiological metabolite of vitamin A is widely applied in the treatment of cancer, skin, neurodegenerative and autoimmune diseases. CYP26A1 enzyme, induced by ATRA in liver and target tissues, metabolizes ATRA into 4-hydroxyl-RA. Inhibition of CYP26A1 metabolic enzyme represents a promising strategy for discovery of new specific anticancer agents. Herein, we describe the design, synthesis and biological evaluation of a series of new amide imidazole derivatives as retinoic acid metabolism blocking agents (RAMBAs) toward CYP26A1 enzyme. First, based on the recent theoretical models (Sun et al., J. Mol. Graph. Model., 2015, 56, 10-19) a series of RAMBAs with novel scaffolds were designed using fragment-based drug discovery approach. Subsequently, the new RAMBAs were synthesized and evaluated for their biological activities. All the compounds demonstrated appropriate enzyme activities and cell activities. The promising inhibitors 20 and 23 with IC50 value of 0.22 μM and 0.46 μM toward CYP26A1, respectively, were further evaluated for CYP selectivity and the metabolic profile of ATRA. Both compounds 20 and 23 showed higher selectivity for CYP26A1 over other CYPs (CYP2D6, CYP3A4) when compared to liarozole. They also showed better inhibitory activities for the metabolism of ATRA when also compared to liarozole. These studies further validated the pharmacophore and structure-activity relationship models obtained about CYP26A1 inhibitors and highlighted the promising activities of the new series of CYP26A1 inhibitors designed from such models. They also paved the way for future development of those candidates as potential drugs.
- Sun, Bin,Liu, Kai,Han, Jing,Zhao, Li-Yu,Su, Xiao,Lin, Bin,Zhao, Dong-Mei,Cheng, Mao-Sheng
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p. 6763 - 6773
(2015/10/20)
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- Cleavable bifunctional coupling agents
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A bifunctional coupling agent for joining a sulfhydryl containing protein or peptide and a metallic radionuclide comprising a sulfhydryl selective electrophile, a chelator containing at least one protected thiol and a organic linking radical containing at least one cleavable site which serves to join said electrophile and said chelator is disclosed. A radiodiagnostic or radiotherapeutic precursor comprising an antibody or antibody fragment and the specified bifunctional coupling agent bound to a sulfhydryl group on the antibody or antibody fragment and a radiodiagnostic or radiotherapeutic agent comprising such precursor having a metallic radionuclide bound thereto are also disclosed.
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- Synthesis of Ethyl cis-2--7-oxo-3-phenyl-6-phthalimido-1-azabicyclohept-3-ene-2-carboxylate and Methyl cis-2-Bromo-3-methyl-8-oxo-7-phthalimido-4-oxa-1-azabicyclooctane-2-carboxylate
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Th synthesis of Δ1-carbapenem and two β-lactams possessing a Br-atom at the N-substituting center not involved in the lactam ring and bearing the carboxyl group is described.The β-lactams having this kind of Br-substitution are more susceptible to nucleophilic attack than those having a conjugated double bond with the N-atom of the β-lactam ring.DBU is found to be an excellent reagent for the elimination of the silyloxy function.Moreover, a simple method for the addition of diethyl phosphite to an α,β-unsaturated double bond using a catalytic amount of NaH is described.
- Hakimelahi, Gholam H.,Jarrahpour, Ali A.
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p. 1501 - 1505
(2007/10/02)
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- Direct O-Acylation of Small Molecules Containing CO2(1-)---HN<--HO Units by a Distorted Amide: Enhancement of Amine Basicity by a Pendant Carboxylate in a Serine Protease Mimic
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The kinetics of the reaction of two series of amino alcohols (ethanol amines and 2-hydroxymethylimidazoles) with a distorted amide were studied as models for the acylation of the serine proteases.The pH/logk2max profiles plateau above the amine pKa, indicating the basic form is active.In all cases, the reactions proceed by initial O-acylation to produce esters.With primary or secondary ethanolamines, subsequent O-->N acyl transfer occurs to give amides.In each series, a Bronsted relationship exists relating the increasing amine pKa with an increasing second-order rate constant for O-acylation.Amino alcohols containing a pendant carboxylate (e.g., serine and the 4(5)- derivative of 2-hydroxymethylimidazole) fit on the Bronsted plots exactly, which suggests the amine pKa controls the reactivity.The role of the carboxylate is to enhance the amine basicity by electrostatic/inductive means.This is particularly effective in solvents of reduced polarity (40percent and 80percent v/v, EtOH/H2O) since the above effects counteract the normal drop in amine pKa exhibited by the other amino alcohols that do not possess the CO2(1-).Both series exhibit low kinetic solvent isotope effects of between 1 and 2.In the imidazole alcohol series, as the amine pKa increases the kinetic solvent isotope effect tends to 1.0.This is discussed in terms of a possible involvement of direct nucleophilic attack of an ammonium alkoxide zwitterion on 1.
- Skorey, K. I.,Somayaji, V.,Brown, R. S.
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p. 1445 - 1452
(2007/10/02)
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- ENANTIOSELECTIVE HYDROLYSIS BY BAKER'S YEAST - II. ESTERS OF N-ACETYL AMINO ACIDS
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D-N-Acetyl amino acid esters were obtained via enantioselective hydrolysis of their racemates by use of fermenting yeast.Evidence is given that proteinases are the enzymes involved.
- Glaenzer, B. I.,Faber, K.,Griengl, H.
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p. 771 - 778
(2007/10/02)
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- Water soluble 3,5-diacetamido-2,4,6-triiodobenzoic acid derivatives
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The invention relates to novel water soluble 3,5-diacetamido-2,4,6-triiodobenzoic acid derivatives, the method for making the same and their use as X-ray contrast agents for vasography, urography, myelography, artrography, fistulography and salpingography.
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