Synthesis and application of L-N-Boc-N-methyl-β-hydroxyvaline in the preparation of a depsipeptide

2005 ◽  
Vol 83 (6-7) ◽  
pp. 793-800 ◽  
Author(s):  
James E Dettwiler ◽  
Laurent Bélec ◽  
William D Lubell
Keyword(s):  
Free Radical ◽  
Amino Acid ◽  
Methyl Ester ◽  
Hydrochloric Acid ◽  
Selective Oxidation ◽  
Building Block ◽  
Amino Alcohol ◽  
Tertiary Alcohol ◽  
Anhydrous Dioxane ◽  
Acidic Conditions

Enantiopure (>99% ee) L-N-tert-butyloxycarbonyl-N-methyl-β-hydroxyvaline (2) was synthesized in six steps and 43% overall yield from D-serine methyl ester (5). Methyl (4S)-N-(9-phenylfluoren-9-yl)-oxazolidine-4-carboxylate (7) was prepared in two steps and 73% yield by N-phenylfluorenation of 5 followed by cyclization of N-(PhF)amino alcohol 6 with formaldehyde and catalytic p-toluenesulfonic acid (PhF = 9-phenylfluoren-9-yl). The addition of MeLi to oxazolidine carboxylate 7 produced the tertiary alcohol 8 in 91% yield. Oxazolidines 8 equilibrated with oxazolidine 9 under acidic conditions. Reduction of pure 8 or the mixture of oxazolidines 8 and 9 with NaCNBH3 and hydrochloric acid in anhydrous dioxane afforded N-methyl amino diol 11 in 86%–92% yields. Attempts to selectively oxidize N-(PhF)amino diol 11 were unsuccessful; however, hydrogenation of 11 in the presence of di-tert-butyl dicarbonate gave the corresponding N-(Boc)amino diol 12 in 82% yield. Selective oxidation of diol 12 was performed using a cocktail containing TEMPO free radical, NaClO2, and NaOCl to give L-N-Boc-N-methyl-β-hydroxyvaline (2) in 87% yield. Coupling of β-hydroxyvaline 2 and (S)-2-hydroxy-3-methylbutanoate (15) was accomplished by using the methodology of Mitsunobu to provide depsipeptide Boc-(S)-HOMeVal-(R)-Hmb (4) for use as a building block in the synthesis of the cyclic antifungal depsipeptide aureobasidin B.Key words: N-methylated amino acid, serine, depsipeptide, aureobasidin.

Nε-Acetyl L-α Lysine Improves Activity and Stability of α-Amylase at Acidic Conditions: A Comparative Study with other Osmolytes

2020 ◽  
Vol 27 (6) ◽  
pp. 551-556
Author(s):  
Nidhya N. Joghee ◽  
Gurunathan Jayaraman ◽  
Masilamani Selladurai
Keyword(s):  
Enzyme Activity ◽  
Amino Acid ◽  
Thermodynamic Stability ◽  
Protective Effects ◽  
Residual Enzyme Activity ◽  
Functional Stability ◽  
Biotechnological Applications ◽  
Optimal Temperature ◽  
Acidic Conditions ◽  
Cellular Components

Background: Nε-acetyl L-α lysine is an unusual acetylated di-amino acid synthesized and accumulated by certain halophiles under osmotic stress. Osmolytes are generally known to protect proteins and other cellular components under various stress conditions. Objective: The structural and functional stability imparted by Nε-acetyl L-lysine on proteins were unknown and hence was studied and compared to other commonly known bacterial osmolytes - ectoine, proline, glycine betaine, trehalose and sucrose. Methods: Effects of osmolytes on the temperature and pH profiles, pH stability and thermodynamic stability of the model enzyme, α-amylase were analyzed. Results: At physiological pH, all the osmolytes under study increased the optimal temperature for enzyme activity and improved the thermodynamic stability of the enzyme. At acidic conditions (pH 3.0), Nε-acetyl L-α lysine and ectoine improved both the catalytic and thermodynamic stability of the enzyme; it was reflected in the increase in residual enzyme activity after incubation of the enzyme at pH 3.0 for 15 min by 60% and 63.5% and the midpoint temperature of unfolding transition by 11°C and 10°C respectively. Conclusion: Such significant protective effects on both activity and stability of α-amylase imparted by addition of Nε-acetyl L-α lysine and ectoine at acidic conditions make these osmolytes interesting candidates for biotechnological applications.

Quantitative helix handedness bias through a single H vs. CH3 stereochemical differentiation

2021 ◽  
Author(s):  
Daniel Bindl ◽  
Elisabeth Heinemann ◽  
Pradeep Kumar Mandal ◽  
Ivan Huc
Keyword(s):  
Amino Acid ◽  
Building Block

A novel chiral aromatic δ-amino acid building block was shown to fully induce handedness in quinoline oligoamide foldamers with the possibility to further increase the bias by combining multiple of...

scholarly journals In Vitro and In Vivo Antioxidant Properties of Taraxacum officinale in Nω-Nitro-l-Arginine Methyl Ester (L-NAME)-Induced Hypertensive Rats

Antioxidants ◽  
2019 ◽  
Vol 8 (8) ◽  
pp. 309
Author(s):  
Olukayode O. Aremu ◽  
Adebola O. Oyedeji ◽  
Opeoluwa O. Oyedeji ◽  
Benedicta N. Nkeh-Chungag ◽  
Constance R. Sewani Rusike
Keyword(s):  
Oxidative Stress ◽  
Free Radical ◽  
Methyl Ester ◽  
Leaf Extract ◽  
Radical Scavenging ◽  
Free Radical Scavenging ◽  
Hypertensive Rats ◽  
Total Antioxidant

Oxidative stress has gained attention as one of the fundamental mechanisms responsible for the development of hypertension. The present study investigated in vitro and in vivo antioxidant effects of 70% ethanol-water (v/v) leaf and root extracts of T. officinale (TOL and TOR, respectively). Total phenolic and flavonoid content of plant extracts were assessed using Folin Ciocalteau and aluminium chloride colorimetric methods; while, 2,2-diphenyl-1-picrlhydrazyl (DPPH), 2,2-azinobis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and ferric reducing antioxidant power (FRAP) protocols were used to determine the free radical scavenging and total antioxidant capacities (TAC), respectively. The in vivo total antioxidant capacity and malondialdehyde acid (MDA) levels for lipid peroxidation tests were performed on organ homogenate samples from Nω-nitro-L-arginine methyl ester (L-NAME)-induced hypertensive rats treated with leaf extract, TOL (500 mg/kg/day) and TOR (500 mg/kg/day) for 21 days. Results showed that compared to TOR, TOL possessed significantly higher (p < 0.01) polyphenol (4.35 ± 0.15 compared to 1.14 ± 0.01) and flavonoid (23.17 ± 0.14 compared to 3 ± 0.05) content; free radical scavenging activity (EC50 0.37 compared to 1.34 mg/mL) and total antioxidant capacities (82.56% compared to 61.54% ABTS, and 156 ± 5.28 compared to 40 ± 0.31 FRAP) and both extracts showed no toxicity (LD50 > 5000 mg/kg). TOL and TOR significantly (p < 0.01) elevated TAC and reduced MDA levels in targets organs. In conclusion, T. officinale leaf extract possesses significant anti-oxidant effects which conferred significant in vivo antioxidant protection against free radical-mediated oxidative stress in L-NAME-induced hypertensive rats.

scholarly journals Synthesis of 2-aminosuberic acid derivatives as components of some histone deacetylase inhibiting cyclic tetrapeptides

2017 ◽  
Vol 13 ◽  
pp. 2153-2156 ◽  
Author(s):  
Shital Kumar Chattopadhyay ◽  
Suman Sil ◽  
Jyoti Prasad Mukherjee
Keyword(s):  
Amino Acid ◽  
Histone Deacetylase ◽  
Building Block ◽  
Suberic Acid ◽  
Metathesis Reaction ◽  
Cross Metathesis ◽  
Important Amino Acid ◽  
New Synthesis ◽  
Cyclic Tetrapeptides ◽  
Derivatives Of

A new synthesis of the important amino acid 2-aminosuberic acid from aspartic acid is reported. The methodology involves the alternate preparation of (S)-2-aminohept-6-enoate ester as a building block and its diversification through a cross-metathesis reaction to prepare the title compounds. The utility of the protocol is demonstrated through the preparation of three suberic acid derivatives of relevance to the design and the synthesis of peptides of biological relevance.

scholarly journals Enantiomerically Pure [2.2]Paracyclophane-4-thiol: A Planar Chiral Sulfur-Based Building Block Readily Available by Resolution with an Amino Acid Chiral Auxiliary

2016 ◽  
Vol 81 (9) ◽  
pp. 3961-3966 ◽  
Author(s):  
Adrien Vincent ◽  
Damien Deschamps ◽  
Thomas Martzel ◽  
Jean-François Lohier ◽  
Christopher J. Richards ◽  
...  
Keyword(s):  
Amino Acid ◽  
Building Block ◽  
Chiral Auxiliary ◽  
Enantiomerically Pure

A kinetic study of the acid autoxidation of tryptophan

1972 ◽  
Vol 25 (10) ◽  
pp. 2139 ◽  
Author(s):  
M Stewart ◽  
CH Nicholls
Keyword(s):  
Free Radical ◽  
Amino Acid ◽  
Kinetic Study ◽  
Acid Hydrolysis ◽  
Soda Glass ◽  
Glass Containers ◽  
Hydrolysis Of

The decomposition of tryptophan in aqueous HC1 at 100�C has been shown to proceed by a free-radical autoxidation mechanism. The acid functions by protonating the amino acid at either the 1- or 3-positions prior to autoxidation and so 1-methyltryptophan is also decomposed under these conditions. Impurities present in the soda glass containers used are shown to be responsible for the initiation of the reaction. The decomposition of tryptophan during the acid hydrolysis of proteins is considered in the light of these results.

UV-Light-Induced Dehydrogenative N-Acylation of Amines with 2-Nitrobenzaldehydes to Give 2-Aminobenzamides

Synthesis ◽  
2022 ◽  
Author(s):  
Dishu Zeng ◽  
Tianbao Yang ◽  
Niu Tang ◽  
Wei Deng ◽  
Jiannan Xiang ◽  
...  
Keyword(s):  
Amino Acid ◽  
Organic Synthesis ◽  
Efficient Method ◽  
Building Block ◽  
Room Temperature ◽  
Uv Light ◽  
Amino Acid Derivatives ◽  
One Pot ◽  
Plausible Mechanism ◽  
High Yields

A simple, mild, green and efficient method for the synthesis of 2-aminobenzamides was highly desired in organic synthesis. Herein, we developed an efficient, one-pot strategy for the synthesis of 2-aminobenzamides with high yields irradiated by UV light. 32 examples proceeded successfully by this photo-induced protocol. The yield reached up to 92%. The gram scale was also achieved easily. This building block could be applied in the preparation of quinazolinones derivatives. Amino acid derivatives could be employed smoothly at room temperature. Finally, a plausible mechanism was proposed.

scholarly journals Selective oxidation of uronic acids into aldaric acids over gold catalyst

RSC Advances ◽  
2015 ◽  
Vol 5 (25) ◽  
pp. 19502-19507 ◽  
Author(s):  
Sari Rautiainen ◽  
Petra Lehtinen ◽  
Jingjing Chen ◽  
Marko Vehkamäki ◽  
Klaus Niemelä ◽  
...  
Keyword(s):  
Selective Oxidation ◽  
Building Block ◽  
Gold Catalyst ◽  
Uronic Acids ◽  
Mild Conditions ◽  
Aldaric Acids

Uronic acids available from hemicelluloses were oxidized into aldaric acids, valuable building block chemicals. Au/Al2O3 oxidized glucuronic and galacturonic acids quantitatively to the corresponding glucaric and galactaric acids at mild conditions.

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