- Synthesis of isotopically labelled amino acids
-
An efficient approach to the enantioselective synthesis of a series of amino acids from either bromoacetyl bromide or glycine is described using a [2,3]-sigmatropic rearrangement to establish the stereogenic centre at C-2 under mild conditions. Protected allylglycine 5 is a valuable building block to several amino acids e.g. hydrolytic cleavage of the auxiliary in 5 followed by deprotection gave L-allylglycine in 92% yield whilst oxidative cleavage of the terminal alkene followed by deprotection gave L-aspartic acid in 67% yield over the 2 steps. Furthermore alkene 5 may be converted to hydroxy ester 8 which is an intermediate for the synthesis of various amino acids including L-lysine and L-proline. Since the enantiomer of sultam 1 is commercially available, the analogous D-amino acids may be synthesised. This chemistry is readily adapted for the incorporation of isotopic labels for example for the synthesis of [1,2-13C2,15N]-L-homoserine 14. Copyright
- Rees, David O.,Bushby, Nick,Harding, John R.,Song, Chuanjun,Willis, Christine L.
-
-
Read Online
- Controlling the Architecture, Coordination, and Reactivity of Nanoparticle Coating Utilizing an Amino Acid Central Scaffold
-
We have developed a versatile strategy to prepare a series of multicoordinating and multifunctional ligands optimized for the surface-functionalization of luminescent quantum dots (QDs) and gold nanoparticles (AuNPs) alike. Our chemical design relies on the modification of l-aspartic acid precursor to controllably combine, through simple peptide coupling chemistry, one or two lipoic acid (LA) groups and poly(ethylene glycol) (PEG) moieties in the same ligand. This route has provided two sets of modular ligands: (i) bis(LA)-PEG, which presents two lipoic acids (higher coordination) appended onto a single end-functionalized PEG, and (ii) LA-(PEG)2 made of two PEG moieties (higher branching, with various end reactive groups) appended onto a single lipoic acid. These ligands are combined with a new photoligation strategy to yield hydrophilic and reactive QDs that are colloidally stable over a broad range of conditions, including storage at nanomolar concentration and under ambient conditions. AuNPs capped with these ligands exhibit excellent stability in various biological conditions and improved resistance against NaCN digestion. This route also provides compact nanocrystals with tunable surface reactivity. As such, we have covalently coupled QDs capped with bis(LA)-PEG-COOH to transferrin to facilitate intracellular uptake. We have also characterized and quantified the coupling of dye-labeled peptides to QD surfaces using fluorescence resonance energy transfer interactions in QD-peptide-dye assemblies.
- Zhan, Naiqian,Palui, Goutam,Kapur, Anshika,Palomo, Valle,Dawson, Philip E.,Mattoussi, Hedi
-
-
Read Online
- Magnesium/hydrazinium monoformate: A new hydrogenation method for removal of some commonly used protecting groups in peptide synthesis
-
Removal of some commonly used protecting groups in peptide synthesis by catalytic transfer hydrogenation employing hydrazinium monoformate and magnesium is described. This method is equally competitive with other methods in deblocking most of the commonly used protecting groups in peptide synthesis. tert-Butyl derived and base labile protecting groups were completely stable under these conditions. The use of Mg/NH2-NH2·HCOOH makes this a rapid, low-cost alternative to palladium and reduces the work-up to a simple and extraction operation.
- Channe Gowda
-
-
Read Online
- 1,2,2,2-Tetrachloroethyl tert-Butyl Carbonate: A Simple and Efficient Reagent for the tert-Butoxycarbonylation of Amines and Amino Acids
-
The reaction of 1-chloroalkyl carbonates with amines affords good yields of the corresponding carbamates.Application to the BOC protection of amino acids is described.
- Barcelo, Gerard,Senet, Jean-Pierre,Sennyey, Gerard
-
-
Read Online
- Mechanically Strong Heterogeneous Catalysts via Immobilization of Powderous Catalysts to Porous Plastic Tablets
-
Main observation and conclusion: We describe a practical and general protocol for immobilization of heterogeneous catalysts to mechanically robust porous ultra-high molecular weight polyethylene tablets using inter-facial Lifshitz-van der Waals Interactions. Diverse types of powderous catalysts, including Cu, Pd/C, Pd/Al2O3, Pt/C, and Rh/C have been immobilized successfully. The immobilized catalysts are mechanistically robust towards stirring in solutions, and they worked well in diverse synthetic reactions. The immobilized catalyst tablets are easy to handle and reused. Moreover, the metal leaching of immobilized catalysts was reduced significantly.
- Li, Tingting,Xu, Bo
-
supporting information
p. 2673 - 2678
(2021/08/03)
-
- Easy-handling and low-leaching heterogeneous palladium and platinum catalysts via coating with a silicone elastomer
-
We have developed a practical protocol for coating of commercial Pd/Al2O3 and Pt/Al2O3 catalysts in micro-powders with a silicone elastomer. Compared to original catalysts, the treated catalysts are easier to weight and transfer, and they are easier to recover by simple filtration. More importantly, the metal leaching of treated catalysts was significantly reduced. The treated catalysts worked very well in diverse hydrogenation reactions.
- Zhou, Mi,Li, Tingting,Xu, Bo
-
supporting information
p. 948 - 952
(2019/03/08)
-
- CONTROLLING THE ARCHITECTURE, COORDINATION, AND REACTIVITY OF NANOPARTICLE COATING UTILIZING AN AMINO ACID CENTRAL SCAFFOLD
-
A series of multicoordinating and multifunctional ligands optimized for the surface-functionalization of luminescent quantum dots (QDs) and gold nanoparticles (AuNPs) alike is disclosed. An L-aspartic acid precursor is modified with functionality, through simple peptide coupling chemistry, one or two lipoic acid (LA) groups and poly(ethylene glycol) (PEG) moieties in the same ligand. These ligands were combined with a new photoligation strategy to yield hydrophilic and reactive QDs that are colloidally stable over a broad range of conditions, including storage at nanomolar concentration and under ambient conditions.
- -
-
Paragraph 0203-0204
(2017/07/06)
-
- Morphological control of self-assembled multivalent (SAMul) heparin binding in highly competitive media
-
Tuning molecular structures of self-assembling multivalent (SAMul) dendritic cationic lipopeptides controls the self-assembled morphology. In buffer, spherical micelles formed by higher generation systems bind polyanionic heparin better than worm-like micelles formed by lower generation systems. In human serum, the binding of spherical micelles to heparin is adversely affected, while worm-like micelles maintain their relative binding ability.
- Rodrigo, Ana C.,Bromfield, Stephen M.,Laurini, Erik,Posocco, Paola,Pricl, Sabrina,Smith, David K.
-
supporting information
p. 6335 - 6338
(2017/07/11)
-
- New reagent for the introduction of Boc protecting group to amines: Boc-OASUD
-
A new reagent, tert-butyl (2,4-dioxo-3-azaspiro [5,5] undecan-3-yl) carbonate (Boc-OASUD) for the preparation of N-Boc-amino acids is described. The Boc-OASUD reacts with amino acids and their esters at room temperature in the presence of a base and gives N-Boc-amino acids and their esters in good yields and purity. Introduction of the Boc group takes place without racemization. The Boc-OASUD, being a solid and more stable, is a better alternative to di-tert-butyl dicarbonate which is low melting and has to be dispensed in plastic containers than glass because of its poor stability.
- Maheswara Rao, B. Leela,Nowshuddin, Shaik,Jha, Anjali,Divi, Murali K.,Rao
-
supporting information
p. 2127 - 2132
(2017/10/31)
-
- Polypeptide formation by heating N-t-butyloxycarbonyl acidic amino acid derivatives
-
An acid labile N-protecting group for amino acids, t-butyloxycarbonyl (Boc) group has deprotected at elevated temperatures. The study describes an application of the lability on heating to synthesis of polypeptides from acidic amino acids. t-Butyloxycarbonyl-acidic amino acids (aspartic acid, glutamic acid and β-aminoglutaric acid) and their anhydrides were heated at the higher temperatures than their melting points. Anhydrides of t-butyloxycarbonyl-aspartic acid and t-butyloxycarbonyl-β-aminoglutaric acid gave polypeptides. Thermal analyses of the substrates clarified the pathway of the polypeptide formation.
- Munegumi,Qing Meng,Harada
-
p. 4716 - 4722
(2014/12/10)
-
- Synthesis of water soluble analogs of arylsulfonylimidazolidinone (JSH-2282)
-
To improve the water solubility of arylsulfonylimidazolidinone (JSH-2282), a potent anti-cancer agent, two urea derivatives, sodium (S)-2-(3-(4-(5-((S)-2- oxo-4-phenylimidazolidin-1-ylsulfonyl)indoline-1-carbonyl)-phenyl)ureido) succinate (2a) and sodium (S)-2-(3-(4-(5-((S)-2-oxo-4-phenylimidazolidin-1- ylsulfonyl)indoline-1-carbonyl)phenyl)ureido)pentanedioate (2b), were synthesized and studied for solubility and anti-cancer activity. Copyright
- Bang, Seong-Cheol,Lee, Ki-Cheul,Sharma, Vinay K.,Sharma, Niti,Yang, Hyun-Sun,Jung, Sang-Hun
-
p. 2011 - 2015
(2013/09/02)
-
- N-linked peptidoresorc[4]arene-based receptors as noncompetitive inhibitors for α-chymotrypsin
-
This paper deals with the design, synthesis, and evaluation of a new series of receptors for protein surface recognition. The design of these agents is based around the attachment of four constrained dipeptide chains onto a central resorc[4]arene scaffold. By varying the sequence, nature, and stereochemistry of the chains we prepared anionically functionalized N-linked peptidoresorc[4] arenes 12, 13, and 17 by Pd/C-catalyzed hydrogenation of the corresponding benzyl esters 10, 11, and 16. From this family of receptors we have identified noncompetitive inhibitors of α-chymotrypsin (ChT), which function by binding to the surface of the enzyme in the neighborhood of the active site cleft (Ki values ranging from 12.4 ± 5.1 μM for free carboxylic acid (+)-12b to 0.76 ± 0.14 μM for benzyl ester (-)-16a). For anionically functionalized receptors 12, 13, and 17 the ChT inhibition is based essentially on electrostatic interaction, and the bound enzyme can be released from the resorcarene surface by increasing the ionic strength, with its activity almost completely restored. For receptors with terminal benzyl ester groups (10 and 16) a hydrophobic network can be suggested.
- Dacquarica, Ilaria,Cerreto, Antonella,Delle Monache, Giuliano,Subrizi, Fabiana,Boffi, Alberto,Tafi, Andrea,Forli, Stefano,Botta, Bruno
-
experimental part
p. 4396 - 4407
(2011/07/08)
-
- Poly(vinyl)chloride supported palladium nanoparticles: Catalyst for rapid hydrogenation reactions
-
Palladium nanoparticles supported over poly(vinyl)chloride matrix (PVC-Pd0) are prepared through an efficient and inexpensive protocol. The catalyst has been characterized by XRD, SEM and TEM and its utility for the reduction of a range of functional groups as well as for the removal of some common protecting groups employed in peptide chemistry is demonstrated.
- Hemantha, Hosahalli P.,Sureshbabu, Vommina V.
-
experimental part
p. 2597 - 2601
(2011/05/12)
-
- A short and efficient synthesis of (S)-(+)-2-(Hydroxymethyl)-6-piperidin-2- one
-
A concise synthesis of (S)-(+)-2-(hydroxymethyl)-6-piperidin-2-one is described that employs l-aspartic acid as chiral pool starting material and Wittig reaction as the key step. Georg Thieme Verlag Stuttgart - New York.
- Upadhyay, Puspesh K.,Kumar, Pradeep
-
experimental part
p. 2512 - 2514
(2010/09/07)
-
- An unexpected product from attempted reductive etherification of a silyl alcohol with an aldehyde
-
Reductive etherification, using BiBr3/Et3SiH, between two modified amino acids, one with a silyl alcohol side chain and one with an aldehyde side chain, gave, not the desired bis-amino acid, but a tetrahydrooxazine, in good yield.
- White, Christopher G.H.,Tabor, Alethea B.
-
p. 6932 - 6937
(2008/02/11)
-
- A simple method for the alkaline hydrolysis of esters
-
A very mild and rapid procedure for the efficient alkaline hydrolysis of esters in non-aqueous conditions has been developed, by the use of dichloromethane/methanol (9:1) as solvent. This method conveniently provides both carboxylic acids and alcohols from the corresponding esters and sodium hydroxide in a few minutes at room temperature. A plausible reaction mechanism is proposed.
- Theodorou, Vassiliki,Skobridis, Konstantinos,Tzakos, Andreas G.,Ragoussis, Valentine
-
p. 8230 - 8233
(2008/03/14)
-
- Polymeric contrast agent
-
The present invention relates to a contrast agent comprising a copolymer having at least a first monomer unit which comprises a metal chelating moiety and a second monomer unit without a chelating moiety and a contrast enhancing metal bound to the chelating moiety. The invention also relates to a process for the preparation of such a contrast agent and the use in magnetic resonance imaging (MRI).
- -
-
Page/Page column 5
(2010/11/08)
-
- Removal of some commonly used protecting groups in peptide syntheses by catalytic transfer hydrogenation with formic acid and 10% palladium on carbon
-
It is shown that HCOOH, a good solvent for most peptides, can be conveniently used as a hydrogen donor for catalytic transfer hydrogenation with less expensive 10% Pd on C when compared to palladium black. The protecting groups that are being successively removed include the Nα-benzyloxycarbonyl, Nε-2-chlorobenzyloxycarbonyl, C-terminal benzyl ester, O-benzyl ether of O-benzyltyrosine, serine or threonine, nitro of nitroarginine and Nim-benzyloxymethyl of histidine.
- Gowda, D. Channe
-
p. 1064 - 1067
(2007/10/03)
-
- A stereocontrolled synthetic route to anti-β-amino alcohols
-
A physiologically indispensable β-amino hydroxy functionality has been constructed with complete anti-stereoselectivity by intramolecular iodoamidation of (Z)-olefinic homoallylic trichloroacetimidates 4-6, 18, 20, 30 and 32, which comprise bulky substituents at the vinylic positions.
- Kang, Sung Ho,Hwang, Yu Sang,Youn, Joo-Hack
-
p. 7599 - 7603
(2007/10/03)
-
- The hydrolysis of primary amide groups in Asn/Gln-containing peptides
-
Peptides Boc-Ala-Asn/Gln-OH and Boc-Asn/Gln-Ala-OH were saponified with barium hydroxide to corresponding Asp/Glu-containing peptides. Under the conditions of saponification, Boc-Asn-Ala-OH additionally afforded Boc-Asp-OH, isopeptide Boc-Asp(Ala)-OH, and Boc-NHSuc > Ala-OH, with the third being the key intermediate in these transformations. Boc-Asp(OMe)-Ala-OMe underwent similar transformations under treatment with diazomethane or triethylamine. Saponification with barium hydroxide was accompanied by a high epimerization of N-terminal amino acid residues, whereas the products of the diazomethane treatment of Boc-Asp(OMe)-Ala-OMe had a low degree of epimerization.
- Onoprienko,Yelin,Miroshnikov
-
p. 361 - 368
(2007/10/03)
-
- 2-(4-acetyl-2-nitrophenyl)ethyl: A new base-labile carboxyl protecting group
-
A new base-labile carboxyl protecting group, the 2-(4-acetyl-2-nitrophenyl)ethyl (Anpe) group is reported and compared with other base-labile protecting groups. The synthesis of the alcohol precursor, 1-[4-(2-hydroxyethyl)-3-nitrophenyl]-1-ethanone, the amino acid derivatives Boc-Asp(Anpe)-OH and Boc-Glu(Anpe)-OH and the conditions under which the carboxyl protecting group can be eliminated are also described.
- Robles,Pedroso,Grandas
-
p. 1261 - 1266
(2007/10/02)
-
- Head-to-tail cyclization and use of C(α)-allyl ester protection improves the yield of cyclic peptides synthesized by the oxime resin method
-
Fully protected and C-terminal free cyclic (lactam-bridged) peptides are assembled by the oxime resin method in high yields and purity applying a four dimensional orthogonal (Boc/Bzl/Fmoc/Al) protection scheme and a head-to-tail cyclization strategy.
- Kapurniotu,Taylor
-
p. 7031 - 7034
(2007/10/02)
-
- L-aspartic acid bis(trimethylsilyl) ester: A convenient starting material for the acylation of L-aspartic acid
-
Reaction of L-aspartic acid with excess of bis(trimethylsilyl)amine under reflux provides optically pure L-aspartic acid bis(trimethylsilyl) ester in quantitative yield. This silyl ester reacts with a variety of acylating reagens in tetrahydrofuran to give N-protected aspartic acids and dipeptides in good yields without racemization.
- Castano, Ana M.,Echavarren, Antonio M.
-
p. 3377 - 3384
(2007/10/02)
-
- Process for the preparation of carbamates, thiocarbamates and ureas
-
The invention relates to a process for preparing carbamic acid derivatives of formula: STR1 in which R1 or R2 denotes a hydrogen atom or a substituted or unsubstituted, saturated or unsaturated aliphatic, cycloaliphatic or heterocyclic radical, or R1 and R2 together form a ring, and Y denotes OR, SR, STR2 groups, R being a substituted or unsubstituted, saturated or unsaturated aliphatic or cycloaliphatic radical, or a substituted or unsubstituted aromatic radical, R3 and R4 denote a hydrogen atom or an aliphatic, cycloaliphatic, araliphatic, aromatic or heterocyclic radical or together form a ring, and R6 and R7 denote a saturated or unsaturated, substituted or unsubstituted aliphatic or cycloaliphatic radical, a hydrogen atom, an alkylthio radical or an alkyloxy radical. According to the process, a compound of formula STR3 is reacted with an α-halogenated derivative of formula STR4 at a temperature of -5° to 150° C. in the presence of an acceptor for hydrohalic acid. The carbamates, thiocarbamates or ureas obtained are very useful, especially as pesticides.
- -
-
-
- Thermal Syntheses of Polypeptides from N-Boc-Amino Acid(Aspartic Acid,β-Aminoglutaric Acid) Anhydrides
-
N-t-Butyloxycarbonyl-amino acid(aspartic acid:Asp, glutamic acid:Glu, β-aminoglutaric acid: β-Agl)anhydrides were deprotected upon heating at temperatures slightly higher than the melting points of these compounds and polypeptides were synthesized easily in high yield.
- Munegumi, Toratane,Meng, Yan-Quing,Harada, Kaoru
-
p. 1643 - 1646
(2007/10/02)
-
- Use of Polar Picolyl Protecting Groups in Peptide Synthesis
-
Protection of serine and threonine side chains with the 4-picolyl group and aspartic and glutamic acids with the 3-picolyl group is described.Picolyl-protected peptide segments are markedly more polar than benzyl-protected analogues, which can facilitate their purification.
- Rizo, Josep,Albericio, Fernando,Romero, Guillermo,Garcia-Echeverria, Carlos,Claret, Josep,et al.
-
p. 5386 - 5389
(2007/10/02)
-
- HYDROLYSE ENANTIOSELECTIVE D'ESTERS D'AMINOACIDE CATALYSEE PAR L'IMIDAZOLE DANS DES MICELLES INVERSES CHIRALES.1300
-
This paper reports the study of the imidazole catalyzed hydrolysis of enantiomeric pairs of three aminoacid esters in reversed micelles prepared from water, heptane and a combination of both racemic or chiral surfactants and of both racemic or chiral (S)2-octanol as cosurfactants.The enantioselectivity observed is important in the combination of chiral surfactant with racemic cosurfactant, and small in the combination of racemic surfactant with chiral cosurfactant, when ω = 20 (ω = / ).This enantioselectivity is also affected by the nature of the cosurfactant, the size of micelles and the nature of the substrate.The results prove that the reaction occurs effectively in a chiral microenvironment, the micelle membrane, and indicate that the cosurfactant is actually present in this membrane.
- Andriamanampisoa, R.,Boyer, B.,Lamity, G.,Roque, J. P.
-
-
- Alkyl 1-Chloroalkyl Carbonates: Reagents for the Synthesis of Carbamates and Protection of Amino Groups
-
The synthesis of 1-chloroalkyl carbonates and their reaction with various type of amines are described.This reaction is useful for the synthesis of carbamate pesticides and for the protection of various amino groups, including amino acids.
- Barcelo, Gerard,Senet, Jean-Pierre,Sennyey, Gerard,Bensoam, Jean,Loffet, Albert
-
p. 627 - 632
(2007/10/02)
-
- PROPERTIES OF Nα,Nca-DI-TERT-BUTYLOXYCARBONYL-ω-CARBAMOYL-α-AMINO ACIDS AND DIRECT SYNTHESIS OF PROTECTED HOMOGLUTAMIC ACID DERIVATIVES
-
The protected carboxamide function of Nα,Nca-di-tert-butyloxy-carbonyl-ω-carbamoyl-α-amino acids worked well with nucleophilic reagents.Applying this novel reactivity, we developed an efficient synthetic route to Nα-tert-butyloxycarbonylhomoglutamic acid and its derivatives, including Nα-tert-butyloxycarbonylhomoglutamic acid δ-benzyl ester, from Nα,Nca-di-tert-butyloxycarbonylhomoglutamine.KEYWORDS - protected homoglutamic acid synthesis; Nca-tert-butyloxycarbonylated carboxamide; hydrolysis; selective deprotection; Nα-tert-butyloxycarbonylhomoglutamic acid δ-benzyl ester; Nα-tert-butyloxycarbonylhomoglutamic acid α-tert-butyl ester; Nα-tert-butyloxycarbonylhomoglutamine; optical purity
- Sakura, Naoki,Hirose, Kyoko,Hashimoto, Tadashi
-
p. 3506 - 3509
(2007/10/02)
-
- 3-Alkoxycarbonyl-2-oxazolones and Their Homopolymers as Highly Preservable Amino-Protecting Reagents. tert-Butoxy-carbonylation and Benzyloxycarbonylation of Amino Groups
-
Highly preservable amino protecting reagents derived from the 2-oxazolone moiety as a common activating mediator have been developed. 3-Alkoxycarbonyl-2-oxazolones serve as easily handled reagents for amino protection, including tert-butoxycarbonylation, benzyloxycarbonylation, p-methoxybenzyloxycarbonylation, methoxycarbonylation and ethoxycarbonylation.For example, high yield N-protection of α-amino acids has been smoothly performed by the use of 3-tert-butoxycarbonyl and 3-benzyloxycarbonyl-2-oxazolones in aqueous solution at room temperature.A series of homopolymers, poly(3-alkoxycarbonyl-2-oxazolone), is readily obtainable by radical-initiated chain reaction of the corresponding 4,5-unsubstituted oxazolone monomers (except for the tert-butoxy derivate, which failed to give polymeric compounds), and these were successfully used for amino protection as well.Use of the polymer reagents greatly simplifies the purification procedure, though a longer reaction time is required.Keywords - 3-alkoxycarbonyl-2-oxazolone; poly(2-alkoxycarbonyl-2-oxazolone); 3-tert-butoxycarbonyl-2-oxazolone; 3-benzyloxycarbonyl-2-oxazolone; amino protection
- Kunieda, Takehisa,Higuchi, Tsunehiko,Abe, Yoshihiro,Hirobe, Masaaki
-
p. 2174 - 2181
(2007/10/02)
-
