- Total Synthesis and Antitrypanosomal Activity of Janadolide and Simplified Analogues
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Janadolide is a cyclic depsipeptide natural product isolated from the marine cyanobacterium Okeania sp. Herein, we describe the total synthesis of janadolide, along with eight simplified analogues, via an efficient solid-phase strategy. Crucial to the synthesis of the natural product was the construction of a key polyketide fragment via an enantioselective (-)-B-chlorodiisopinocampheylborane-mediated reduction and a B-alkyl Suzuki reaction. Janadolide and the simplified analogues exhibited antitrypanosomal activity against pathogenic Trypanosoma brucei rhodesiense and Trypanosoma cruzi parasites.
- Chung, Jonathan H.,Corcilius, Leo,Geraghty, Kieran,Kaiser, Marcel,Payne, Richard J.,Tang, Arthur H.
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supporting information
(2020/04/20)
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- Aldehydes as potential acylating reagents for oxidative esterification by inorganic ligand-supported iron catalysis
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The oxidative esterification of various aldehydes with alcohols could be achieved by a heterogeneous iron(iii) catalyst supported on a ring-like POM inorganic ligand under mild conditions, affording the corresponding esters, including several drug molecules and natural products, in high yields. ESI-MS and control experiments demonstrated that POM-FeV(O) was the active catalytic species and the plausible mechanism was presented. More importantly, the 6th run of the iron catalyst recycles shows only a slight decrease in the yield.
- Yu, Han,Wang, Jingjing,Wu, Zhikang,Zhao, Qixin,Dan, Demin,Han, Sheng,Tang, Jiangjiang,Wei, Yongge
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supporting information
p. 4550 - 4554
(2019/08/21)
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- Batch Versus Flow Lithiation–Substitution of 1,3,4-Oxadiazoles: Exploitation of Unstable Intermediates Using Flow Chemistry
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1,3,4-Oxadiazoles are a common motif in pharmaceutical chemistry, but few convenient methods for their modification exist. A fast, convenient, high yielding and general α-substitution of 1,3,4-oxadiazoles has been developed using a metalation-electrophilic trapping protocol both in batch and under continuous flow conditions in contradiction to previous reports which suggest that α-metalation of this ring system results in ring fragmentation. In batch, lithiation is accomplished at an industrially convenient temperature, ?30 °C, with subsequent trapping giving isolated yields of up to 91 %. Under continuous flow conditions, metalation is carried out at room temperature, and subsequent in flow electrophilic trapping gave up to quantitative isolated yields. Notably, lithiation in batch at room temperature results only in ring fragmentation and we propose that the superior mixing in flow allows interception and exploitation of an unstable intermediate before decomposition can occur.
- Wong, Jeff Y. F.,Tobin, John M.,Vilela, Filipe,Barker, Graeme
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supporting information
p. 12439 - 12445
(2019/09/06)
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- Direct Catalytic Alcoholysis of Unactivated 8-Aminoquinoline Amides
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Direct catalytic alcoholysis of unactivated amides is one of the most difficult challenges in organic chemistry, and an applicable method for cleaving amides used as directing groups in regioselective functionalization reactions has not been reported. Herein, we report direct catalytic alcoholysis of 8-aminoquinoline amides, which are highly effective directing groups in regioselective functionalization reactions. The reactions proceeded with a simple combination of substrates, air-stable catalysts, and alcohols, affording the corresponding esters in good yields with broad functional group tolerance. Highly chemoselective cleavage of the 8-aminoquinoline amides in the presence of related carbonyl functionalities and preliminary mechanistic studies are also described.
- Deguchi, Toru,Xin, Hai-Long,Morimoto, Hiroyuki,Ohshima, Takashi
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p. 3157 - 3161
(2017/06/09)
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- Conversion of alcohols to alkyl esters and carboxylic acids using heterogeneous palladium-based catalysts
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Disclosed are methods for synthesizing an ester or a carboxylic acid from an organic alcohol. To form the ester one reacts, in the presence of oxygen gas, the alcohol with methanol or ethanol. This reaction occurs in the presence of a catalyst comprising palladium and a co-catalyst comprising bismuth, tellurium, lead, cerium, titanium, zinc and/or niobium (most preferably at least bismuth and tellurium). Alternatively that catalyst can be used to generate an acid from that alcohol, when water is also added to the reaction mix.
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- Decarbonylative radical coupling of α-aminoacyl tellurides: Single-step preparation of γ-amino and α,β-diamino acids and rapid synthesis of gabapentin and manzacidin A
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A new radical-based coupling method has been developed for the single-step generation of various γ-amino acids and α,β-diamino acids from α-aminoacyl tellurides. Upon activation by Et3B and O2 at ambient temperature, α-aminoacyl tellurides were readily converted into α-amino carbon radicals through facile decarbonylation, which then reacted intermolecularly with acrylates or glyoxylic oxime ethers. This mild and powerful method was effectively incorporated into expeditious synthetic routes to the pharmaceutical agent gabapentin and the natural product (-)-manzacidin A.
- Nagatomo, Masanori,Nishiyama, Hayato,Fujino, Haruka,Inoue, Masayuki
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supporting information
p. 1537 - 1541
(2015/01/30)
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- CRYSTALLINE FORM OF A BETA-LACTAMASE INHIBITOR
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This disclosure provides compositions containing solid forms of (2S,5R)-2-(5-(3-aminopropyl)-1,3,4-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]octan-6-yl hydrogen sulfate, and methods of manufacturing and using these compositions.
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Paragraph 0113; 0115
(2015/04/28)
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- Hydroaminomethylation of Olefins with Aminomethyltrifluoroborate by Photoredox Catalysis
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A photocatalytic hydroaminomethylation of olefins with N-protected aminomethyltrifluoroborates has been developed. This methodology provides a new strategy for the introduction of a primary aminomethyl group onto electron-deficient C=C bonds. This reaction constitutes a facile entry into synthetically useful γ-aminobutyric acid (GABA) derivatives such as baclofen.
- Miyazawa, Kazuki,Koike, Takashi,Akita, Munetaka
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p. 2749 - 2755
(2016/02/18)
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- Aerobic oxidation of diverse primary alcohols to methyl esters with a readily accessible heterogeneous Pd/Bi/Te catalyst
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Efficient aerobic oxidative methyl esterification of primary alcohols has been achieved with a heterogeneous catalyst consisting of 1 mol % Pd/charcoal (5 wt %) in combination with bismuth(III) nitrate and tellurium metal. The Bi and Te additives significantly increase the reaction rate, selectivity, and overall product yields. This readily accessible catalyst system exhibits a broad substrate scope and is effective with both activated (benzylic) and unactivated (aliphatic) alcohols bearing diverse functional groups.
- Powell, Adam B.,Stahl, Shannon S.
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supporting information
p. 5072 - 5075
(2013/10/22)
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- 1,3,4-OXADIAZOLE AND 1,3,4-THIADIAZOLE BETA-LACTAMASE INHIBITORS
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β-Lactamase inhibitor compounds (BLIs) are disclosed, including compounds that have activity against class A, class C or class D β-lactamases. Methods of manufacturing the BLIs, and uses of the compounds in the preparation of pharmaceutical compositions and antibacterial applications are also disclosed.
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- Double molecular recognition with aminoorganoboron complexes: Selective alcoholysis of β-dicarbonyl derivatives
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Double duty: Aminoorganoboron (AOB) complexes recognize alcohol and β-dicarbonyl units, and thereby facilitate chemo- and site-selective alcoholysis of the latter (see scheme). The complex activates both reaction partners. This strategy enables C-C, C-N, and C-O bond cleavage in addition/elimination reactions under near neutral pH conditions and provides a new method for functional group conversions. Copyright
- Oishi, Shunsuke,Saito, Susumu
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supporting information; experimental part
p. 5395 - 5399
(2012/06/18)
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- Designing hybrid foldamers: The effect on the peptide conformational bias of β- Versus α- and γ-linear residues in alternation with (1R,2S)-2-aminocyclobutane-1-carboxylic acid
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Several oligomers constructed with (1R,2S)-2-aminocyclobutane-1-carboxylic acid and glycine, β-alanine, and γ-amino butyric acid (GABA), respectively, joined in alternation have been synthesized and studied by means of NMR and CD experiments as well as with computational calculations. Results account for the spacer length effect on folding and show that conformational preference for these hybrid peptides can be tuned from β-sheet-like folding for those containing a C2 or C4 linear segment to a helical folding for those with a C3 spacer between cyclobutane residues. The introduction of cyclic spacers between these residues does not modify the extended ribbon-type structure previously manifested in poly(cis-cyclobutane) β-oligomers.
- Celis, Sergio,Gorrea, Esther,Nolis, Pau,Illa, Ona,Ortuno, Rosa M.
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p. 861 - 868
(2012/02/05)
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- Dibutylphosphate (DBP) mediated synthesis of cyclic N,N′- disubstituted urea derivatives from amino esters: A comparative study
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The N,N′-disubstituted urea derivatives such as amino acid hydantoins and dihydrouracil derivatives were prepared starting from natural and unnatural amino acid esters using dibutylphosphate (DBP). During the attempted synthesis of N-heterocycles with larger than six-membered rings containing the N,N′-disubstituted urea functionalities, three unexpected products namely squamolone, N-methyl pyrrolidine-2-one, and diketopiperazine were isolated.
- Agrawal, Sumit K.,Sathe, Manisha,Kaushik, M. P.,Halve, A. K.
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supporting information
p. 5996 - 5999,4
(2020/08/20)
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- Structure-activity relationship studies of 1-(4-chloro-2,5-dimethoxyphenyl) -3-(3-propoxypropyl)thiourea, a non-nucleoside reverse transcriptase inhibitor of human immunodeficiency virus type-1
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The reverse transcriptase (RT) of the human immunodeficiency virus type-1 (HIV-1) is still a prime target for drug development due to the continuing need to block drug-resistant RT mutants by new inhibitors. We have previously identified 1-(4-chloro-2,5-dimethoxyphenyl)-3-(3-propoxypropyl)thiourea, compound 1, as a potent RT inhibitor from an available chemical library. Here, we further modified this compound to study structure-activity relationships when replacing various groups in the molecule. Different functional groups were systematically introduced on the aromatic ring and the aliphatic chain of the compound was modified. The effect of these modifications on viral infectivity was then evaluated. The most potent compound found was propyl 4-(amino-N-(4-chloro-2,5-dimethoxyphenyl)methanethioamino)butanoate, 45c, which inhibited infectivity with a calculated IC50 of about 1.1 μM. Docking studies identified potential important interactions between the top scoring ligands and HIV-1 RT, and the predicted relative affinity of the ligands was found to be in agreement with the experimental results.
- Weitman, Michal,Lerman, Keti,Nudelman, Abraham,Major, Dan Thomas,Hizi, Amnon,Herschhorn, Alon
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experimental part
p. 447 - 467
(2011/03/20)
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- Hydrogenation of N-acylcarbamates and N-acylsulfonamides catalyzed by a bifunctional [Cp*Ru(PN)] complex
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Awakening of the Cp one: the bifunctional complex 1 facilitates the interaction with substrates bearing less electrophilic carbon atoms than ketones, epoxides, and imides. The title reaction was applicable to the reduction of Evans' asymmetric alkylation products to the chiral alcohols along with gtood recovery of the chiral oxazolidinone auxiliary. EWG=electron- withdrawing group.
- Ito, Masato,Koo, Lee Wei,Himizu, Akio,Kobayashi, Chika,Sakaguchi, Ayaka,Ikariya, Takao
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scheme or table
p. 1324 - 1327
(2009/06/30)
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- Ruthenium tetroxide oxidation of cyclic N-acylamines by a single layer method: formation of ω-amino acids
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The ruthenium tetroxide oxidation of cyclic N-acyl amines by a 10% NaIO4 aqueous solution containing tert-butanol as a single layer system resulted in the endo-cyclic C-N bond cleavage to afford the ω-amino acids as almost sole products in good yields, while a similar oxidation under the double layer using a NaIO4 aqueous solution, and ethyl acetate gave the N-acyl lactams.
- Kaname, Mamoru,Yoshifuji, Shigeyuki,Sashida, Haruki
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p. 2786 - 2788
(2008/09/19)
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- Scandium triflate catalyzed transesterification of carboxylic esters
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The direct transesterification of carboxylic esters is efficiently catalyzed with Sc(OTf)3 (10 mol%) in boiling alcoholic solvent. Methyl, ethyl, isopropyl, and allyl esters were prepared from a broad range of different substrates in high yields. The application of microwave irradiation led to significantly reduced reaction times. Georg Thieme Verlag Stuttgart.
- Remme, Nicole,Koschek, Katharina,Schneider, Christoph
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p. 491 - 493
(2007/12/27)
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- Enzymatic removal of carboxyl protecting groups. 2. Cleavage of the benzyl and methyl moieties
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Enzymes are versatile reagents for the efficient removal of methyl and benzyl protecting groups. An esterase from Bacillus subtilis (BS2) and a lipase from Candida antarctica (CAL-A) allow a mild and selective removal of these moieties in high yields without affecting other functional groups.
- Barbayianni, Efrosini,Fotakopoulou, Irene,Schmidt, Marlen,Constantinou-Kokotou, Violetta,Bornscheuer, Uwe T.,Kokotos, George
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p. 8730 - 8733
(2007/10/03)
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- Design, synthesis and anticonvulsive activity of analogs of γ-vinyl GABA
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For the development of new anticonvulsive agents, analogs of γ-vinyl GABA (vigabatrin) containing GABA, γ-vinyl GABA, valproic acid, nipecotic acid or isonipecotic acid moieties were prepared and evaluated for their anticonvulsive activities. Most of the prepared compounds showed moderate anticonvulsive activities. Among them compounds 10 and 16 displayed the most potent anticonvulsive activity and a broader spectrum compared to vigabatrin.
- Zhao, Long-Xuan,Park, Jae Gyu,Moon, Yoon-Soo,Basnet, Arjun,Choi, Jongwon,Kim, Eun-Kyung,Jeong, Tae Cheon,Jahng, Yurngdong,Lee, Eung-Seok
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p. 381 - 388
(2007/10/03)
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