Direct synthesis of N-terminal thiazolidine-containing peptide thioesters from peptide hydrazides

2018 ◽  
Vol 54 (66) ◽  
pp. 9127-9130 ◽  
Author(s):  
Kohei Sato ◽  
Shoko Tanaka ◽  
Kazuki Yamamoto ◽  
Yosuke Tashiro ◽  
Tetsuo Narumi ◽  
...  
Keyword(s):  
Direct Synthesis ◽  
Synthetic Method ◽  
Peptide Thioesters

We report a simple and promising synthetic method to oxidize peptide hydrazides containing N-terminal thiazolidine as a protected cysteine.

scholarly journals Direct Synthesis and Applications of Solid Silylzinc Reagents

2021 ◽  
Author(s):  
Ramesh Rasappan ◽  
Revathi Chandrasekaran ◽  
Feba Thomas Pulikkottil ◽  
Krishna Suresh
Keyword(s):  
Detrimental Effect ◽  
Functional Group ◽  
Direct Synthesis ◽  
Cross Coupling ◽  
Synthetic Methods ◽  
Synthetic Method ◽  
General Applicability ◽  
Alkyl Aryl ◽  
Synthetic Utility ◽  
First Time

The increased synthetic utility of organosilanes motivates researchers to develop a milder and more practical synthetic methods. Silylzinc reagents, which are typically the most functional group tolerant, are notoriously difficult to synthesize because they are obtained by a pyrophoric reaction of silyllithium, particularly Me3 SiLi itself prepared by the reaction of MeLi and disilane. Furthermore, the dissolved LiCl in silylzinc may have a detrimental effect. A synthetic method that can avoid silyllithium and involves a direct synthesis of silylzinc reagents from silyl halides is arguably the simplest and economical strategy. We describe for the first time, the direct synthesis of PhMe2 SiZnI and Me3 SiZnI reagents by employing a coordinating TMEDA ligand, as well as single crystal XRD structures. Importantly, they can be obtained as solid and stored for longer periods of time. We demonstrate their significance in cross-coupling of various free alkyl/aryl/alkenyl carboxylic acids with broader functional group tolerance and API derivatives. The general applicability and efficiency of solid Me3 SiZnI are shown in a wide variety of reactions including alkylation, arylation, allylation, 1,4-addition, acylation and more.

scholarly journals Low-Temperature Vapor-Phase Synthesis of Single-Crystalline Gold Nanostructures: Toward Exceptional Electrocatalytic Activity for Methanol Oxidation Reaction

Nanomaterials ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 595
Author(s):  
Yang ◽  
Park ◽  
Kim ◽  
Kang
Keyword(s):  
Methanol Oxidation ◽  
Vapor Phase ◽  
Oxidation Reaction ◽  
Direct Synthesis ◽  
Methanol Oxidation Reaction ◽  
Synthetic Method ◽  
Phase Synthesis ◽  
Single Crystalline ◽  
Electrochemical Devices ◽  
Vapor Phase Synthesis

Au nanostructures (Au NSs) have been considered promising materials for applications in fuel cell catalysis, electrochemistry, and plasmonics. For the fabrication of high-performance Au NS-based electronic or electrochemical devices, Au NSs should have clean surfaces and be directly supported on a substrate without any mediating molecules. Herein, we report the vapor-phase synthesis of Au NSs on a fluorine-doped tin oxide (FTO) substrate at 120 °C and their application to the electrocatalytic methanol oxidation reaction (MOR). By employing AuCl as a precursor, the synthesis temperature for Au NSs was reduced to under 200 °C, enabling the direct synthesis of Au NSs on an FTO substrate in the vapor phase. Considering that previously reported vapor-phase synthesis of Au NSs requires a high temperature over 1000 °C, this proposed synthetic method is remarkably simple and practical. Moreover, we could selectively synthesize Au nanoparticles (NPs) and nanoplates by adjusting the location of the substrate, and the size of the Au NPs was controllable by changing the reaction temperature. The synthesized Au NSs are a single-crystalline material with clean surfaces that achieved a high methanol oxidation current density of 14.65 mA/cm2 when intimately supported by an FTO substrate. We anticipate that this novel synthetic method can widen the applicability of vapor-phase synthesized Au NSs for electronic and electrochemical devices.

Direct Synthesis of Vicinal Tricarbonyl Amides by Coupling of α-Oxo Acid Chlorides with Carbamoylsilanes

Synthesis ◽  
2019 ◽  
Vol 51 (15) ◽  
pp. 2977-2983
Author(s):  
Yuling Han ◽  
Yuping Li ◽  
Shenghua Han ◽  
Pengpeng Zhang ◽  
Jianxin Chen
Keyword(s):  
Oxalyl Chloride ◽  
Direct Synthesis ◽  
Coupling Reaction ◽  
Cross Coupling ◽  
Synthetic Method ◽  
Acid Chlorides ◽  
Mild Conditions ◽  
Cross Coupling Reaction ◽  
The Cross

A convenient synthetic method for vicinal tricarbonyl amides by the cross-coupling reaction of α-oxo acid chlorides with carbamoylsilanes is developed. The reaction tolerates a broad range of substituents on the amido nitrogen of carbamoylsilanes, and directly affords good yields of vicinal tricarbonyl amides under mild conditions without use of oxidants. The reaction of carbamoylsilanes with oxalyl chloride has also been explored, and is accompanied by decarbonylation to give vicinal tricarbonyl amides.

scholarly journals Direct Synthesis and Applications of Solid Silylzinc Reagents

2021 ◽  
Author(s):  
Ramesh Rasappan ◽  
Revathi Chandrasekaran ◽  
Feba Thomas Pulikkottil ◽  
Krishna Suresh
Keyword(s):  
Detrimental Effect ◽  
Functional Group ◽  
Direct Synthesis ◽  
Cross Coupling ◽  
Synthetic Methods ◽  
Synthetic Method ◽  
General Applicability ◽  
Alkyl Aryl ◽  
Synthetic Utility ◽  
First Time

The increased synthetic utility of organosilanes motivates researchers to develop a milder and more practical synthetic methods. Silylzinc reagents, which are typically the most functional group tolerant, are notoriously difficult to synthesize because they are obtained by a pyrophoric reaction of silyllithium, particularly Me3 SiLi itself prepared by the reaction of MeLi and disilane. Furthermore, the dissolved LiCl in silylzinc may have a detrimental effect. A synthetic method that can avoid silyllithium and involves a direct synthesis of silylzinc reagents from silyl halides is arguably the simplest and economical strategy. We describe for the first time, the direct synthesis of PhMe2 SiZnI and Me3 SiZnI reagents by employing a coordinating TMEDA ligand, as well as single crystal XRD structures. Importantly, they can be obtained as solid and stored for longer periods of time. We demonstrate their significance in cross-coupling of various free alkyl/aryl/alkenyl carboxylic acids with broader functional group tolerance and API derivatives. The general applicability and efficiency of solid Me3 SiZnI are shown in a wide variety of reactions including alkylation, arylation, allylation, 1,4-addition, acylation and more.

scholarly journals Reversing aggregation: direct synthesis of nanocatalysts from bulk metal. Cellulose nanocrystals as active support to access efficient hydrogenation silver nanocatalysts

2016 ◽  
Vol 18 (1) ◽  
pp. 129-133 ◽  
Author(s):  
Madhu Kaushik ◽  
Alain You Li ◽  
Reuben Hudson ◽  
Mitra Masnadi ◽  
Chao-Jun Li ◽  
...  
Keyword(s):  
Cellulose Nanocrystals ◽  
Direct Synthesis ◽  
Synthetic Method ◽  
Bulk Metal

A highly atom-economical synthetic method to access nanocatalysts from bulk metal is described.

Direct Cyclization of Alkenyl Thioester via Transition Metal‐hydrogen Atom Transfer/radical‐polar Crossover Mechanism

2019 ◽  
Author(s):  
Shiori Date ◽  
Kensei Hamasaki ◽  
Karen Sunagawa ◽  
Hiroki Koyama ◽  
Chikayoshi Sebe ◽  
...  
Keyword(s):  
Natural Products ◽  
Hydrogen Atom ◽  
Transition Metal ◽  
Hydrogen Atom Transfer ◽  
Synthetic Method ◽  
Atom Transfer ◽  
Reaction Conditions ◽  
Hydride Hydrogen ◽  
Sulfur Heterocycles ◽  
One Step

<div>We report here a catalytic, Markovnikov selective, and scalable synthetic method for the synthesis of saturated sulfur heterocycles, which are found in the structures of pharmaceuticals and natural products, in one step from an alkenyl thioester. Unlike a potentially labile alkenyl thiol, an alkenyl thioester is stable and easy to prepare. The powerful Co catalysis via a cobalt hydride hydrogen atom transfer and radical-polar crossover mechanism enabled simultaneous cyclization and deprotection. The substrate scope was expanded by the extensive optimization of the reaction conditions and tuning of the thioester unit.</div>

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