- Synthesis of 9-fluorenylmethoxycarbonyl-protected amino aldehydes
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9-Fluorenylmethoxycarbonyl-protected amino aldehydes could be efficiently prepared in good yields by using two methods: (i) NaBH4 reduction of Fmoc-protected mixed anhydrides, followed by the Swern oxidation of the alcohols; and (ii) LiAlH
- Wen, James J.,Crews, Craig M.
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- Stepwise Automated Solid Phase Synthesis of Naturally Occurring Peptaibols Using FMOC Amino Acid Fluorides
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The standard methods of stepwise solid phase synthesis according to Merrifield could not previously be applied to the synthesis of the important naturally occurring peptaibols because of difficulties arising from the pronounced steric hindrance caused by α,α-dialkylated amino acids (incomplete coupling, especially to adjacent similarly constituted units, racemization due to slow coupling to hindered amino acids, etc.), chain degradation due to the presence of acid-labile Aib-Pro linkages, and the lack of any general method for the loading of C-terminal amino alcohols to resin supports.Following recent work on model systems, it is now shown that the adoption of Fmoc amino acid fluorides as coupling reagents makes possible the facile, general assembly of such peptides.The method was demonstrated for alamethicin F30 and F50, saturnisporin SA III, and trichotoxin A50J.The crude products were of remarkable purity.Amino acid analysis, mass spectral data, and comparison of the synthetic alamethicins with samples of naturally occurring material confirmed the success of the syntheses.No significant amount of racemization (0.8percent) was found for any of the chiral amino acids present.The first step of the synthesis involved a new general method for assembly of C-terminal peptide alcohols via the use of o-chlorotrityl resin.In addition, model studies on the question of racemization during the coupling of Fmoc amino acid fluorides are reported.
- Wenschuh, Holger,Beyermann, Michael,Haber, Hanka,Seydel, Joachim K.,Krause, Eberhard,et al.
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- Active carbonate resins: Application to the solid-phase synthesis of alcohol, carbamate and cyclic peptides
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N,N'-disuccinimidyl carbonate (DSC) has been successfully used to generate carbonates and carbamates on conventional hydroxymethyl and aminomethyl based resins. This methodology extends the applicability of such linkers, which were initially designed for
- Alsina, Jordi,Rabanal, Francesc,Chiva, Cristina,Giralt, Ernest,Albericio, Fernando
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- An efficient synthesis of N-protected β-aminoethanesulfonyl chlorides: Versatile building blocks for the synthesis of oligopeptidosulfonamides
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A very efficient method for the synthesis of β-aminoethanesulfonyl chlorides is described. These aliphatic functionalized sulfonyl chlorides are accessible starting from a variety of protected amino acids, including those having functionalized side chains
- Brouwer,Monnee,Liskamp
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- DMSO-aided o-iodoxybenzoic acid (IBX) oxidation of Fmoc-protected amino alcohols
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A fast and highly convenient procedure for the formation of Fmoc-protected amino aldehydes from the corresponding alcohols using 1.1 equiv. of IBX in the presence of dimethylsulfoxide (DMSO) is discussed. This procedure leads to the clean synthesis of Fmo
- Chen, Jack J.,Aduda, Vince
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- O-Alkyl S-(Pyridin-2-yl)carbonothiolates: Operationally Simple and Highly Nitrogen-Selective Reagents for Alkoxy Carbonylation of Amino Groups
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Amino groups are selectively protected in good yields by reaction with O-Alkyl S-(pyridin-2-yl)carbonothiolates in an appropriate solvent at room temperature in air. Even glucosamine, which contains multiple hydroxyl groups, is selectively N-protected in methanol.
- Hashimoto, Yoshimitsu,Morita, Nobuyoshi,Suzuki, Tomoyuki,Tamura, Osamu,Tanaka, Kosaku
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p. 899 - 902
(2020/05/28)
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- Staudinger/aza-Wittig reaction to access Nβ-protected amino alkyl isothiocyanates
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A unified approach to access Nβ-protected amino alkyl isothiocyanates using Nβ-protected amino alkyl azides through a general strategy of Staudinger/aza-Wittig reaction is described. The type of protocol used to access isothiocyanates depends on the availability of precursors and also, especially in the amino acid chemistry, on the behavior of other labile groups towards the reagents used in the protocols; fortunately, we were not concerned about both these factors as precursor-azides were prepared easily by standard protocols, and the present protocol can pave the way for accessing title compounds without affecting Boc, Cbz and Fmoc protecting groups, and benzyl and tertiary butyl groups in the side chains. The present strategy eliminates the need for the use of amines to obtain title compounds and thus, this method is step-economical; additional advantages include retention of chirality, convenient handling and easy purification. A few hitherto unreported compounds were also prepared, and all final compounds were completely characterized by IR, mass, optical rotation, and 1H and 13C NMR studies.
- Santhosh,Durgamma,Shekharappa,Sureshbabu, Vommina V.
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p. 4874 - 4880
(2018/07/15)
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- Fast and Facile Synthesis of 4-Nitrophenyl 2-Azidoethylcarbamate Derivatives from N-Fmoc-Protected α-Amino Acids as Activated Building Blocks for Urea Moiety-Containing Compound Library
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A fast and facile synthesis of a series of 4-nitrophenyl 2-azidoethylcarbamate derivatives as activated urea building blocks was developed. The N-Fmoc-protected 2-aminoethyl mesylates derived from various commercially available N-Fmoc-protected α-amino ac
- Chen, Ying-Ying,Chang, Li-Te,Chen, Hung-Wei,Yang, Chia-Ying,Hsin, Ling-Wei
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p. 131 - 136
(2017/04/24)
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- A greener, efficient and catalyst-free ultrasonic-assisted protocol for the n-fmoc protection of amines
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A simple, eco-sustainable method for the N-(9-fluorenylmethoxycarbonyl) (N-Fmoc) protection of various structurally amines under ultrasonic irradiation is reported. The corresponding N-Fmoc derivatives were obtained in good to excellent yields within short reaction time. The reaction proceeds without the formation of any side product. Mildness, efficiency and easier work are the main advantages of this new protocol.
- Mansouri, Rachida,Aouf, Zineb,Lakrout, Salah,Berredjem, Malika,Aouf, Nour-Eddine
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p. 546 - 550
(2016/03/19)
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- Hydrodehalogenation of alkyl iodides with base-mediated hydrogenation and catalytic transfer hydrogenation: Application to the asymmetric synthesis of N-protected α-methylamines
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We report a very mild synthesis of N-protected α-methylamines from the corresponding amino acids. Carboxyl groups of amino acids are reduced to iodomethyl groups via hydroxymethyl intermediates. Reductive deiodination to methyl groups is achieved by hydrogenation or catalytic transfer hydrogenation under alkaline conditions. Basic hydrodehalogenation is selective for the iodomethyl group over hydrogenolysis-labile protecting groups, such as benzyloxycarbonyl, benzyl ester, benzyl ether, and 9-fluorenyloxymethyl, thus allowing the conversion of virtually any protected amino acid into the corresponding N-protected α-methylamine.
- Mandal, Pijus K.,Birtwistle, J. Sanderson,McMurray, John S.
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p. 8422 - 8427
(2015/03/18)
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- An expedient route for the reduction of carboxylic acids to alcohols employing 1-propanephosphonic acid cyclic anhydride as acid activator
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A simple and efficient method for the synthesis of alcohols from the corresponding carboxylic acids is described. Activation of carboxylic acid with 1-propane phosphonic acid cyclic anhydride (T3P) and subsequent reduction of the intermediate phosphonic anhydride with NaBH4 yield the alcohol in excellent yields with good purity in less duration. Reduction of several alkyl/aryl carboxylic acids and Nα-protected amino acids/peptide acids as well as Nβ-protected amino acids was successfully carried out to obtain corresponding alcohols in good yields and the products characterized. The procedure is mild, safe, simple and the isolation of the products is easy.
- Nagendra,Madhu,Vishwanatha,Sureshbabu, Vommina V.
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experimental part
p. 5059 - 5063
(2012/09/22)
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- A simple synthesis of N β-Fmoc/Z-amino alkyl thiols and their use in the synthesis of N β-Fmoc/Z-amino alkyl sulfonic acids
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A simple and efficient protocol for the synthesis of Nβ- Fmoc/Z-amino alkyl thiols is described. The approach uses sodium pyrosulfite-mediated hydrolysis of isothiouronium salts resulting from the reaction between N-protected aminoalkyl iodides and thiourea. N-Protected taurines were prepared through performic acid oxidation of the thiols and the products were further utilized for the synthesis of dipeptidosulfonamides. Georg Thieme Verlag Stuttgart - New York.
- Sureshbabu,Vishwanatha,Vasantha
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p. 1037 - 1042
(2010/07/06)
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- N-urethane-protected amino alkyl isothiocyanates: Synthesis, isolation, characterization, and application to the synthesis of thioureidopeptides
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(Chemical Equation Presented) Synthetically useful N-Fmoc amino-alkyl isothiocyanates have been described, starting from protected amino acids. These compounds have been synthesized in excellent yields by thiocarbonylation of the monoprotected 1,2-diamines with CS2/TEA/p-TsCl, isolated as stable solids, and completely characterized. The procedure has been extended to the synthesis of amino alkyl isothiocyanates from Boc- and Z-protected amino acids as well. The utility of these isothiocyanates for peptidomimetics synthesis has been demonstrated by employing them in the preparation of a series of dithioureidopeptide esters. Boc-Gly-OH and Boc-Phe-OH derived isothiocyanates 9a and 9c have been obtained as single crystals and their structures solved through X-ray diffraction. They belong to the orthorhombic crystal system, and have a single molecule in the asymmetric unit (Z′ = 1). 9a crystallizes in the centrosymmetric space group Pbca, while 9c crystallizes in the noncentrosymmetric space group P212121.
- Sureshbabu, Vommina V.,Naik, Shankar A.,Hemantha,Narendra,Das, Ushati,Guru Row, Tayur N.
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supporting information; experimental part
p. 5260 - 5266
(2009/12/06)
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- Efficient synthesis of N-fmoc-aminoalkoxy pentafluorophenyl carbonates: Application for the synthesis of oligopeptidyl carbamates
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N-Fmoc-Aminoalkoxy pentafluorophenyl carbonates have been synthesized through the reaction of N-Fmoc-aminoalkoxy carbonyl chloride with pentafluorophenol. The reaction was clean and high yielding, and the products have been fully characterized using infra
- Sureshbabu, Vommina V.,Hemantha
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body text
p. 3555 - 3566
(2009/12/26)
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- Solid-phase synthesis of azidomethylene inhibitors targeting cysteine proteases
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An efficient strategy for the solid-phase synthesis of azidomethylene inhibitors targeting cysteine proteases is described. The method is highlighted by its compatibility with readily available building blocks, as well as its ability to accommodate differ
- Yang, Peng-Yu,Wu, Hao,Lee, Mei Yin,Xu, Ashley,Srinivasan, Rajavel,Yao, Shao Q.
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supporting information; experimental part
p. 1881 - 1884
(2009/04/18)
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- Asymmetric synthesis of highly substituted azapolycyclic compounds via 2-alkenyl sulfoximines: Potential scaffolds for peptide mimetics
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The application of metalated, enantiomerically pure acyclic and cyclic 2-alkenyl sulfoximines for the synthesis of highly substituted aza(poly)cyclic ring systems is described. The method relies on a one-pot combination of a reagent-controlled allyl transfer reaction to α- or β-amino aldehydes, followed by a Michael-type cyclization of the intermediate vinyl sulfoximines generated in the first step. The sulfur-free target compounds are preferentially obtained by samarium iodide treatment of the sulfonimidoyl substituted heterocycles. In addition to this methodological work, initial results on the biological activity of selected examples are reported. Furthermore, a concept for the transformation of peptidic lead structures into non-peptide mimetics is described, and the relevance of the new approach to highly substituted azaheterocycles in this context is discussed.
- Reggelin, Michael,Junker, Bernd,Heinrich, Timo,Slavik, Stefan,Buehle, Philipp
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p. 4023 - 4034
(2007/10/03)
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- Synthesis and applications of β-aminoethanesulfonyl azides
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A very efficient method for the synthesis of β-aminoethanesulfonyl azides is descibed. These aliphatic sulfonyl azides are accessible starting from a variety of protected amino acids, including those having functionalized side chains. Furthermore, these s
- Brouwer, Arwin J.,Merkx, Remco,Dabrowska, Katarzyna,Rijkers, Dirk T. S.,Liskamp, Rob M. J.
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p. 455 - 460
(2007/10/03)
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- Synthesis of Fmoc-protected β-amino alcohols and peptidyl alcohols from Fmoc-amino acid/peptide acid azides
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An efficient synthesis of Nα-9H-fluoren-9- ylmethoxycarbony(Fmoc)-β-amino alcohols by the reduction of Fmoc-α-amino acyl azides employing aqueous NaBH4 as a reducing agent has been described. The reduction is found to be simple and almost complete. All the Fmoc-β-amino alcohols prepared are fully characterized by 1H and 13C NMR and mass spectrometry. Further, the method is extended for the reduction of seven Fmoc-dipeptidyl acids to the corresponding alcohols. Their reduction is also found to be smooth and complete.
- Babu, Vommina V. Suresh,Kantharaju,Sudarshan, Naremaddepalli S.
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p. 1880 - 1886
(2007/10/03)
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- High loading polymer reagents based on polycationic Ultraresins. Polymer-supported reductions and oxidations with increased efficiency
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Ultraresin 1 was prepared from highly branched polyethylene imine (M n=10,000) via reductive cross-linking with terephthaldialdehyde. Following quaternization with methyl iodide, the polycationic Ultraresin 2, with iodide as a counterion, was obtained. These novel resins combine low swelling with high mechanical stability. By anion exchange polycationic Ultraresins carrying borohydride (3) and periodate (22) were generated and were investigated as very high loading polymer reagents. Ultra-borohydride resin 3 had a reducing activity of up to 12 mmol/g depending on the substrate. It proved successful in diverse reductions including those of aldehydes, ketones, and nitroolefines. The resin was employed in the reductive amination of aldehydes with an excess of amines, which were removed by the use of a scavenger resin. Periodate resin 22 was obtained with an active loading of up to 5.4 mmol/g and was employed in oxidations of sulfides, diols, hydroquinones, and hydrazines.
- Barth, Michael,Shah, Syed Tasadaque Ali,Rademann, J?rg
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p. 8703 - 8709
(2007/10/03)
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- Solid-phase synthesis of oligourea peptidomimetics employing the Fmoc protection strategy
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A solid-phase-Fmoc-based-synthesis strategy is described for oligourea peptidomimetics as well as a convenient general synthesis approach for the preparation of the required building blocks 5a-j and 5k. These are suitable for use in peptide or robot synthesizers, which is illustrated by the synthesis of oligourea peptidomimetics of part of Leu-enkephalin (10) and a neurotensin derivative (17).
- Boeijen,Van Ameijde,Liskamp
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p. 8454 - 8462
(2007/10/03)
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- Solid-phase synthesis of C-terminal peptide aldehydes from amino acetals anchored to a backbone amide linker (BAL) handle
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Peptide aldehydes were synthesized, starting from amino acetals, by a Solid-phase backbone amide linker (BAL) strategy. (C) 2000 Elsevier Science Ltd.
- Guillaumie,Kappel,Kelly,Barany,Jensen
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p. 6131 - 6135
(2007/10/03)
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- Mild reduction of carboxylic acids to alcohols using cyanuric chloride and sodium borohydride
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Several carboxylic acids, including N-Boc, N-Cbz and N-Fmoc amino acids were reduced to the corresponding alcohols by activation of the carboxy function with cyanuric chloride and N-methylmorpholine followed by reduction with aqueous sodium borohydride.
- Falorni, Massimo,Porcheddu, Andrea,Taddei, Maurizio
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p. 4395 - 4396
(2007/10/03)
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- Synthesis of enantiopure N-and C-protected homo-β-amino acids by direct homologation of α-amino acids
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Enantiopure N-and/or C-protected homo-β-amino acids are prepared readily and in good yields from N-protected α-amino acids with the same side chain, via reduction of the carboxyl function and conversion of the resulting N-protected β-amino alcohol into the corresponding β-amino iodide and then β-amino cyanide. The key step of this strategy is represented by the synthesis of the enantiopure N-protected β-amino iodides 2 and 3 that are smoothly obtained from the parent amino alcohols 1 by polymer bound triarylphosphine-I2 complex in anhydrous dichloromethane.
- Caputo, Romualdo,Cassano, Ersilia,Longobardo, Luigi,Palumbo, Giovanni
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p. 12337 - 12350
(2007/10/02)
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- Chiral N-Protected β-Iodoamines from α-Aminoacids: a General Synthesis
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N-Protected D- or L-β-iodoamines (as 2), which are useful intermediates for the preparation of chiral β-aminoacids, are obtained smoothly from β-aminols (as 1) in two steps and high yields.
- Caputo, Romualdo,Cassano, Ersilia,Longobardo, Luigi,Palumbo, Giovanni
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p. 167 - 168
(2007/10/02)
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- Rationally Designed "Dipeptoid" Analogues of CCK. α-Methyltryptophan Derivatives as Highly Selective and Orally Active Gastrin and CCK-B Antagonists with Potent Anxiolytic Properties
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This paper describes the synthesis and structure-activity relationships (SAR) leading to the first rational design of "dipeptoid" analogues of the neuropeptide cholecystokinin (CCK).Compounds *,S*)>-4-2-3-(1H-indol-3-yl)-2-m
- Horwell, David C.,Hughes, John,Hunter, John C.,Pritchard, Martyn C.,Richardson, Reginald S.,at al.
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p. 404 - 414
(2007/10/02)
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- PREPARATION OF N-PROTECTED α-AMINO ALCOHOLS BY ACETOXYBOROHYDRIDE REDUCTION OF N-PROTECTED α-AMINO ACID ESTERS
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N-Protected α-amino alcohols were prepared by reduction of N-protected α-amino acid esters by sodium acetoxyborohydride in dioxane at elevated temperature.The reductions proceed with excellent yields and without racemisation.Reduction of the carbamate protecting groups was not observed.
- Soucek, Milan,Urban, Jan,Saman, David
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p. 761 - 765
(2007/10/02)
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