- Transition Metal-Free N-Arylation of Amino Acid Esters with Diaryliodonium Salts
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A transition metal-free approach for the N-arylation of amino acid derivatives has been developed. Key to this method is the use of unsymmetric diaryliodonium salts with anisyl ligands, which proved important to obtain high chemoselectivity and yields. The scope includes the transfer of both electron deficient, electron rich and sterically hindered aryl groups with a variety of different functional groups. Furthermore, a cyclic diaryliodonium salt was successfully employed in the arylation. The N-arylated products were obtained with retained enantiomeric excess.
- Kervefors, Gabriella,Kersting, Leonard,Olofsson, Berit
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supporting information
p. 5790 - 5795
(2021/03/08)
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- Postsynthetic Modification of Phenylalanine Containing Peptides by C-H Functionalization
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New methods for peptide modification are in high demand in drug discovery, chemical biology, and materials chemistry; methods that modify natural peptides are particularly attractive. A Pd-catalyzed, C-H functionalization protocol for the olefination of phenylalanine residues in peptides is reported, which is compatible with common amino acid protecting groups, and the scope of the styrene reaction partner is broad. Bidentate coordination of the peptide to the catalyst appears crucial for the success of the reaction.
- Terrey, Myles J.,Perry, Carole C.,Cross, Warren B.
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supporting information
p. 104 - 108
(2019/01/11)
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- Insights into the Desaturation of Cyclopeptin and its C3 Epimer Catalyzed by a non-Heme Iron Enzyme: Structural Characterization and Mechanism Elucidation
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AsqJ, an iron(II)- and 2-oxoglutarate-dependent enzyme found in viridicatin-type alkaloid biosynthetic pathways, catalyzes sequential desaturation and epoxidation to produce cyclopenins. Crystal structures of AsqJ bound to cyclopeptin and its C3 epimer ar
- Liao, Hsuan-Jen,Li, Jikun,Huang, Jhih-Liang,Davidson, Madison,Kurnikov, Igor,Lin, Te-Sheng,Lee, Justin L.,Kurnikova, Maria,Guo, Yisong,Chan, Nei-Li,Chang, Wei-Chen
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supporting information
p. 1831 - 1835
(2018/01/27)
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- Toward the synthesis and improved biopotential of an n-methylated analog of a proline-rich cyclic tetrapeptide from marine bacteria
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An N-methylated analog of a marine bacteria-derived natural proline-rich tetracyclopeptide was synthesized by coupling the deprotected dipeptide fragments Boc-L-prolyl-L-N-methylleucine-OH and L-prolyl-L-N-methylphenylalanine-OMe. A coupling reaction was accomplished utilizing N,N0-Dicyclohexylcarbodidimde (DCC) and 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC·HCl) as coupling agents and Triethylamine (TEA) or N-methylmorpholine (NMM) as the base in the presence of the racemization suppressing agent. This was followed by the cyclization of the linear tetrapeptide fragment under alkaline conditions. The structure of the synthesized cyclooligopeptide was confirmed using quantitative elemental analysis, FTIR (Fourier-transform infrared spectroscopy),1H NMR (Nuclear magnetic resonance spectroscopy),13C NMR, and mass spectrometry. From the bioactivity results, it was clear that the newly synthesized proline-rich tetracyclopeptide exhibited better anthelmintic potential against Megascoplex konkanensis, Pontoscotex corethruses, and Eudrilus eugeniae at a concentration of 2 mg/mL as well as improved antifungal activity against pathogenic dermatophytes Trichophyton mentagrophytes and Microsporum audouinii at a concentration of 6 μg/mL, as compared to non-methylated tetracyclopeptide. Moreover, N-methylated tetracyclopeptide displayed significant activity against pathogenic Candida albicans.
- Dahiya, Rajiv,Kumar, Suresh,Khokra, Sukhbir Lal,Gupta, Sheeba Varghese,Sutariya, Vijaykumar B.,Bhatia, Deepak,Sharma, Ajay,Singh, Shamjeet,Maharaj, Sandeep
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- Reductive N-methylation of amines with calcium hydride and Pd/C catalyst
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The methylation of amines by paraformaldehyde in the presence of calcium hydride as a source of hydrogen and palladium on charcoal as catalyst was studied. Depending on the quantity of paraformaldehyde, monomethylated and dimethylated amines were selectively and efficiently prepared in one pot with good yields.
- Guyon, Carole,Duclos, Marie-Christine,Métay, Estelle,Lemaire, Marc
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p. 3002 - 3005
(2016/07/06)
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- Ring-closing metathesis based total synthesis of ciliatamides A and B and their structural confirmation
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Protecting group dependant ring-closing metathesis based approach to the total synthesis of the revised structures of ciliatamides A and B has been described. The current synthetic strategy utilizes the amino acid as starting material to introduce both the stereogenic centers. However, usage of non-racemizing reagents (EDC·HCl, HATU/NMM); for amide coupling and Grubbs' second generation catalyst for caprolactam ring synthesis makes the present approach more convenient to get the correct conclusion on absolute stereochemistry. Thus, on the basis of similar optical rotation values with the Lindsley's reported data, this synthesis further supported for the actual stereochemistry of both ciliatamides A and B is (R,R).
- Avula, Krishnakumari,Mohapatra, Debendra K.
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supporting information
p. 1715 - 1717
(2016/04/04)
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- Preparation of the optically pure N-methyl amino ester method and product
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The invention belongs to the field of organic synthesis of amino acids and discloses a method for preparing optically pure N-methyl amino-acid ester. The method comprises the following steps of carrying out esterification reaction on amino acid as a starting raw material and aldehyde to form an imine intermediate, carrying out reductive amination in the presence of palladium carbon, and carrying out hydrogenation and debenzylation to finally synthesize optically pure N-methyl amino-acid ester. The method has the advantages of simplicity in method, mild reaction conditions and good adaptability and side chains of D-type or L-type amino acid do not need to be protected.
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- Synthesis of N-methyl L-phenylalanine for total synthesis of pepticinnamin e
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The target compounds 3, 10 and 11 were synthesized through different N-methylation strategies. The concise and efficient preparation of them in large scale was developed and 3, 10 and 11 were obtained in suitable form used for both nitrogen-end and oxygen-end extension in next coupling reaction in peptides synthesis, specifically in total synthesis of natural pepticinnamin E.
- Sun, Dequn,Zhang, Lingzi,Wang, Jin
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p. 319 - 322
(2012/09/07)
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- Selective C-N bond oxidation: demethylation of N-methyl group in N-arylmethyl-N-methyl-α-amino esters utilizing N-iodosuccinimide (NIS)
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Demethylation of N-methyl group in N-methyl-N-arylmethyl-α-amino esters was accomplished by the oxidation of the amino group using the N-iodosuccinimide (NIS)/acetonitrile system followed by treatment with O-methylhydroxylamine hydrochloride. This combina
- Katoh, Takahiro,Watanabe, Tsunefumi,Nishitani, Mitsuyoshi,Ozeki, Minoru,Kajimoto, Tetsuya,Node, Manabu
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p. 598 - 600
(2008/09/16)
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- Synthesis of chiral, monodentate aminophosphane and phosphoramidite ligands derived from amino acid esters: Application in Rh-catalysed asymmetric olefin hydrogenation reactions
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Six chiral monodentate ligands combining a 1,3-dioxa-2- phosphacycloheptadinaphthyl moiety [(R)- or (S)-binoP] either with a phenylalanine- or with an alanine-derived fragment were synthesised. The new phosphoramidites are all relatively air stable. Relat
- Eberhardt, Luc,Armspach, Dominique,Matt, Dominique,Toupet, Loic,Oswald, Benoit
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p. 4153 - 4161
(2008/03/14)
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- "One-pot" methylation of N-nosyl-α-amino acid methyl esters with diazomethane and their coupling to prepare N-methyl dipeptides
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N-Nosyl-α-amino acid methyl esters are methylated quantitatively with diazomethane. After proper deprotection of the amino function by treatment with the reagent system mercaptoacetic acid/sodium methoxide, the obtained N-methyl amino acid methyl esters are coupled with N-Fmoe amino acid chlorides to afford the corresponding dipeptides. The obtained products do not show any detectable extent of racemization by 1H NMR and HPLC.
- Di Gioia, Maria Luisa,Leggio, Antonella,Le Pera, Adolfo,Liguori, Angelo,Napoli, Anna,Siciliano, Carlo,Sindona, Giovanni
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p. 7416 - 7421
(2007/10/03)
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- LiOH-mediated N-monoalkylation of α-amino acid esters and a dipeptide ester using activated alkyl bromides
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Selective N-monoalkylation of α-amino esters with activated alkyl bromides was studied using various alkali or alkali earth metal bases. In the production of N-monoalkylated amino ester derivatives and suppression of N,N-dialkylation, lithium hydroxide wa
- Cho, Jong Hyun,Kim, B.Moon
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p. 1273 - 1276
(2007/10/03)
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- Antibacterial cyclopeptide alkaloids from the bark of Condalia buxifolia.
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The cyclopeptide alkaloid, named condaline-A, was isolated from the root bark of Condalia buxifolia Reissek (Rhamnaceae), along with the known compounds adouetine-Y', scutianine-B, and scutianine-C. Their structures were determined by spectroscopic analys
- Morel, Ademir F,Araujo, Carla A,da Silva, Ubiratan F,Hoelzel, Solange C S M,Zachia, Renato,Bastos, Nelci R
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p. 561 - 566
(2007/10/03)
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- A new inhibitor design strategy for carboxypeptidase A as exemplified by N-(2-Chloroethyl)-N-methylphenylalanine
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N-(2-Chloroethyl)-N-methylphenylalanine was designed and synthesized in an optically active form as a novel class of mechanism-based inactivator for carboxypeptidase A (CPA). It was anticipated that the chloroethylamino moiety of the CPA bound inhibitor undergoes an intramolecular SN2 reaction to generate a chemically reactive species (an aziridinium ion) which is expectedly subjected to a nucleophilic attack by the carboxylate of Glu-270, leading to covalent modification of the carboxylate. The irreversible nature of the inhibition of CPA by the inhibitor was supported by the kinetic data: the enzyme lost its enzymic activity in a time-dependent manner in the presence of the inhibitor and the inactivated CPA failed to regain the activity upon dialysis. Interestingly, the (R)-isomer that belongs to the D-series was more potent than its enantiomer.
- Park, Jung Dae,Lee, Kyung Joo,Kim, Dong H.
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p. 237 - 243
(2007/10/03)
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- N-monoalkylation of α-amino acid esters under solid-liquid PTC conditions
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N-(2-Nitrophenylsulfonyl)- (o-NBS-AA-OMe, 4) and N-(4- Nitrophenylsulfonyl)-α-amino acid methyl esters (p-NBSAA-OMe, 5) were N- alkylated with a variety of alkyl halides 6 under solid-liquid phase-transfer catalysis (SL-PTC) conditions, affording the alkylated products o-NBS-N-R2- AA-OMe 7 and p-NBS-N-R2-AA-OMe 8 in excellent yields without any detectable racemization.
- Albanese, Domenico,Landini, Dario,Lupi, Vittoria,Penso, Michele
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p. 1443 - 1449
(2007/10/03)
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- The first total synthesis of (-)-benzomalvin A via intramolecular Aza-Wittig reactions
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The first total synthesis of (-)-benzomalvin A 1, which possesses quinazolin-4(3H)-one moiety and 1,4-benzodiazepin-5-one moiety, was described. Both of 6- and 7-membered ring skeletons were efficiently constructed by intramolecular aza-Wittig reactions as the key reactions.
- Sugimori, Toshiyuki,Okawa, Tomohiro,Eguchi, Shoji,Yashima, Eiji,Okamoto, Yoshio
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p. 869 - 870
(2007/10/03)
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- Immonium Ion Based Synthetic Methodology: A Novel Method for the N-Methylation of Dipeptides and Amino Acid Derivatives via Retro Aza Diels-Alder Reactions
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A novel method for the N-methylation of amino acid derivatives and dipeptides is detailed that features facile room-temperature retro Diels-Alder reactions of N-substituted 2-azanorbornenes with trapping of the incipient immonium ion with triethylsilane/trifluoroacetic acid.
- Grieco, Paul A.,Bahsas, Ali
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p. 5746 - 5749
(2007/10/02)
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