- Simple and efficient Fmoc removal in ionic liquid
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A mild method for an efficient removal of the fluorenylmethoxycarbonyl (Fmoc) group in ionic liquid was developed. The combination of a weak base such as triethylamine and [Bmim][BF4] makes the entire system more efficient for the cleavage at room temperature of various amines and amino acid methyl esters in short reaction times. The procedure works well even in the case of N-Fmoc amino acids bearing acid-sensitive protecting groups and of N-alkylated amino acid methyl esters. The solvent-free condition provides a complementary method for Fmoc deprotection in solution phase peptide synthesis and modern organic synthesis.
- Di Gioia,Costanzo,De Nino,Maiuolo,Nardi,Olivito,Procopio
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p. 36482 - 36491
(2017/08/02)
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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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Paragraph 0065-0066
(2017/04/13)
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- Lewis acid catalysed methylation of N-(9H-fluoren-9-yl)methanesulfonyl (Fms) protected lipophilic α-amino acid methyl esters
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This work reports an efficient Lewis acid catalysed N-methylation procedure of lipophilic α-amino acid methyl esters in solution phase. The developed methodology involves the use of the reagent system AlCl3/diazomethane as methylating agent and α-amino acid methyl esters protected on the amino function with the (9H-fluoren-9-yl)methanesulfonyl (Fms) group. The removal of Fms protecting group is achieved under the same conditions to those used for Fmoc removal. Thus the Fms group can be interchangeable with the Fmoc group in the synthesis of N-methylated peptides using standard Fmoc-based strategies. Finally, the absence of racemization during the methylation reaction and the removal of Fms group were demonstrated by synthesising a pair of diastereomeric dipeptides.
- Leggio, Antonella,Alò, Danila,Belsito, Emilia Lucia,Di Gioia, Maria Luisa,Romio, Emanuela,Siciliano, Carlo,Liguori, Angelo
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p. 644 - 650
(2015/08/03)
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- Deprotection/reprotection of the amino group in α-amino acids and peptides. A one-pot procedure in [Bmim][BF4] ionic liquid
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This paper presents an efficient one-pot protocol for the sequential deprotection/reprotection of the α-amino group in α-amino acid and dipeptide methyl esters. [Bmim][BF4] is used as the solvent in the entire process. In particular, the use of the ionic liquid allows for rapid and clean removal of the 4-nitrobenzenesulfonyl (nosyl) group and for facile subsequent tert-butyloxycarbonylation of the free α-amino function under very mild conditions. N-Boc-α-amino acid as well as peptide derivatives are isolated in excellent yields, and do not require any further purification. Absolute configurations of the precursors are totally preserved during the process.
- Di Gioia,Barattucci,Bonaccorsi,Leggio,Minuti,Romio,Temperini,Siciliano
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p. 2678 - 2686
(2014/01/06)
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- Total synthesis, absolute configuration, and biological activity of xyloallenoide A
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The novel natural product xyloallenoide A, isolated from the marine mangrove endophytic fungus from the South China Sea, and its diastereoisomer xyloallenoide A1, which contain N-methyl-substituted amino acids, were synthesized. The absolute configurations of the amino acid units of xyloallenoide A were finally confirmed to be L-Lys, Me-D-Val, and Me-L-Ala. This report represents a practical and attractive alternative for the synthesis of N-methyl-substituted cyclotripeptides. In the preliminary bioassay, synthetic xyloallenoide A showed marginal activities against KB (IC50=9.6 mm) and KBv200 cells (IC50=10.3 μm), and xyloallenoide A1 was inactive against KB and KBv200 cells.
- Wang, San-Yong,Xu, Zhong-Liang,Wang, Hui,Li, Chun-Rong,Fu, Li-Wu,Pang, Ji-Yan,Li, Jing,She, Zhi-Gang,Lin, Yong-Cheng
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p. 973 - 982
(2012/08/08)
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- Marine cyclotripeptide X-13 promotes angiogenesis in zebrafish and human endothelial cells via PI3K/Akt/eNOS signaling pathways
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Cyclotripeptide X-13 is a core of novel marine compound xyloallenoide A isolated from mangrove fungus Xylaria sp. (no. 2508). We found that X-13 dose-dependently induced angiogenesis in zebrafish embryos and in human endothelial cells, which was accompanied by increased phosphorylation of eNOS and Akt and NO release. Inhibition of PI3K/Akt/eNOS by LY294002 or L-NAME suppressed X-13-induced angiogenesis. The present work demonstrates that X-13 promotes angiogenesis via PI3K/Akt/eNOS pathways.
- Lu, Xi-Lin,Xu, Zhong-Liang,Yao, Xiao-Li,Su, Feng-Juan,Ye, Cheng-Hui,Li, Jing,Lin, Yong-Cheng,Wang, Guang-Lei,Zeng, Jin-Sheng,Huang, Ru-Xun,Ou, Jing-Song,Sun, Hong-Shuo,Wang, Li-Ping,Pang, Ji-Yan,Pei, Zhong
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scheme or table
p. 1307 - 1320
(2012/08/08)
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- Diastereoselective synthesis of quaternary α-amino acids from diketopiperazine templates
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Sequential enolate alkylations of (S)-N(1)-methyl-5-methoxy-6-isopropyl-3, 6-dihydropyrazin-2-one and (S)-N(1)-p-methoxybenzyl-5-methoxy-6-isopropyl-3,6- dihydropyrazin-2-one proceed with excellent levels of diastereoselectivity (>90% de) affording quaternary α-amino acids in high enantiomeric excess (>98% ee) after deprotection and hydrolysis. This journal is The Royal Society of Chemistry.
- Davies, Stephen G.,Christopher Garner,Ouzman, Jaqueline V. A.,Roberts, Paul M.,Smith, Andrew D.,Snow, Emma J.,Thomson, James E.,Tamayo, Juan A.,Vickers, Richard J.
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p. 2138 - 2147
(2008/03/14)
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- Enhanced diastereoselectivity via confinement: Photoisomerization of 2,3-diphenylcyclopropane-1-carboxylic acid derivatives within zeolites
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From the perspective of asymmetric induction, the photochemistry of 24 chiral esters and amides of cis-2,3-diphenylcyclopropane-1-carboxylic acid from excited singlet and triplet states has been investigated within zeolites. The chiral auxiliaries placed
- Sivaguru,Sunoj, Raghavan B.,Wada, Takehiko,Origane, Yumi,Inoue, Yoshihisa,Ramamurthy, Vaidhyanathan
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p. 6533 - 6547
(2007/10/03)
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- Stereocontrolled synthesis of onchidins
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(Chemical Equation Presented) The first total synthesis of a molecule possessing the stereochemistry proposed for onchidin is described. The structure synthesized appears to be different from that of the marine natural product.
- Peng, Yungui,Pang, Heung Wing,Ye, Tao
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p. 3781 - 3784
(2007/10/03)
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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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- Synthesis and utilization of a novel glycine derived chiral precursor, based on a recyclable L-prolinol auxiliary, for the enantioselective preparation of α-amino acids and their N-methyl derivatives
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α-Amino acids and their N-methyl derivatives are synthesized in fairly high optical purity employing a new glycine derived template based on a recyclable L-prolinol chiral auxiliary.
- Pandey,Reddy,Das
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p. 3175 - 3178
(2007/10/03)
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- DIRECTED METALLATION OF TETRAMIC ACIDS: A NEW SYNTHESIS OF 3-ACYL TETRAMIC ACIDS
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3-Acyl tetramic acids have been prepared by directed metallation at C-3 of the 4-O-methyl ethers of pyrrolidine-2,4-diones, reaction of the vinyl-lithium derivative with aldehydes, and oxidation and hydrolysis of the adducts.
- Jones, Raymond C. F.,Peterson, Graeme E.
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p. 4751 - 4754
(2007/10/02)
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