scholarly journals Biomimetic studies using artificial system. IV. Biomimetic peptide synthesis by using multi-functionalized crown ethers as a novel enzyme model. A new concepts in mimicking of enzyme-catalyzed bond-forming reactions.

1989 ◽  
Vol 37 (4) ◽  
pp. 912-919 ◽  
Author(s):  
Shigeki SASAKI ◽  
Kenji KOGA
Keyword(s):  
Peptide Synthesis ◽  
Crown Ethers ◽  
Artificial System ◽  
Bond Forming ◽  
New Concepts ◽  
Enzyme Model ◽  
Bond Forming Reactions

scholarly journals Minimizing HCN in DIC/Oxyma Mediated Amide Bond Forming Reactions

2020 ◽  
Author(s):  
Marion Erny ◽  
Marika Lundqvist ◽  
Jon H. Rasmussen ◽  
Olivier Ludemann-Hombouger ◽  
Frédéric Bihel ◽  
...  
Keyword(s):  
Carboxylic Acid ◽  
Peptide Synthesis ◽  
Hydrogen Cyanide ◽  
Reaction Rate ◽  
Solid Support ◽  
Amide Bond ◽  
Prussic Acid ◽  
Bond Forming ◽  
H Nmr ◽  
Bond Forming Reactions

<p>Aiming at advancing protocols for safer, environmentally sensible peptide synthesis we report our findings with regards to the occurrence of hydrogen cyanide (HCN, prussic acid) in amide bond forming reactions mediated by diisopropylcarbodiimide (DIC) and ethyl (hydroxyimino)cyanoacetate (Oxyma). We have determined that HCN is always formed in amide bond forming reactions on solid support in N,N-dimethylformamide (DMF) when employing DIC/Oxyma. In an attempt to minimize the formation of prussic acid by means of preventing the linear DIC/Oxyma adduct <b>2</b> from cyclizing to oxadiazole <b>3</b> and in turn releasing HCN, we evaluated a series of greener solvents such as N-butylpyrrolidinone (NBP), NBP/ethyl acetate (EtOAc, 1:1), methyl 5-(dimethylamino)-2-methyl-5-oxopentanoate (PolarClean, PC), and PC/EtOAc (1:1). We found that the ratio between <b>2</b> and <b>3</b> greatly depends on the solvent used and consequently, we further examined DMF, NBP, NBP/EtOAc (1:1) and NBP/EtOAc (1:4) as solvents for DIC/Oxyma mediated amidations on solid support and in solution. We found that using carboxylic acid/Oxyma/DIC in a 1:1:1 ratio the rate of HCN formation decreases in the following order DMF>NBP>NBP/EtOAc (1:1)>NBP/EtOAc (1:4) while the reaction rate increases in order of DMF~NBPin situ scavenging of the HCN formed. We carried out DIC/Oxyma mediated amidation of Fmoc-Gly-OH + (S)-(-)-1-phenylethylamine in DMF-d<sub>7</sub> with 0, 5 and 10 equiv of dimethyl trisulfide (DMTS) as HCN scavenger. The formation of HCN and rate of amidation was monitored by <sup>1</sup>H NMR, revealing that DMTS scavenges HCN without inhibiting the rate of amidation. DIC/Oxyma mediated amidations of Fmoc‑Ser(<i>t</i>‑Bu)‑OH with (S)-(‑)-1-phenylethylamine in DMF and NBP/EtOAc (1:4) with and without 10 equiv of DMTS were carried out and found to be comparable.</p>

scholarly journals Minimizing HCN in DIC/Oxyma Mediated Amide Bond Forming Reactions

2020 ◽  
Author(s):  
Marion Erny ◽  
Marika Lundqvist ◽  
Jon H. Rasmussen ◽  
Olivier Ludemann-Hombouger ◽  
Frédéric Bihel ◽  
...  
Keyword(s):  
Carboxylic Acid ◽  
Peptide Synthesis ◽  
Hydrogen Cyanide ◽  
Reaction Rate ◽  
Solid Support ◽  
Amide Bond ◽  
Prussic Acid ◽  
Bond Forming ◽  
H Nmr ◽  
Bond Forming Reactions

<p>Aiming at advancing protocols for safer, environmentally sensible peptide synthesis we report our findings with regards to the occurrence of hydrogen cyanide (HCN, prussic acid) in amide bond forming reactions mediated by diisopropylcarbodiimide (DIC) and ethyl (hydroxyimino)cyanoacetate (Oxyma). We have determined that HCN is always formed in amide bond forming reactions on solid support in N,N-dimethylformamide (DMF) when employing DIC/Oxyma. In an attempt to minimize the formation of prussic acid by means of preventing the linear DIC/Oxyma adduct <b>2</b> from cyclizing to oxadiazole <b>3</b> and in turn releasing HCN, we evaluated a series of greener solvents such as N-butylpyrrolidinone (NBP), NBP/ethyl acetate (EtOAc, 1:1), methyl 5-(dimethylamino)-2-methyl-5-oxopentanoate (PolarClean, PC), and PC/EtOAc (1:1). We found that the ratio between <b>2</b> and <b>3</b> greatly depends on the solvent used and consequently, we further examined DMF, NBP, NBP/EtOAc (1:1) and NBP/EtOAc (1:4) as solvents for DIC/Oxyma mediated amidations on solid support and in solution. We found that using carboxylic acid/Oxyma/DIC in a 1:1:1 ratio the rate of HCN formation decreases in the following order DMF>NBP>NBP/EtOAc (1:1)>NBP/EtOAc (1:4) while the reaction rate increases in order of DMF~NBPin situ scavenging of the HCN formed. We carried out DIC/Oxyma mediated amidation of Fmoc-Gly-OH + (S)-(-)-1-phenylethylamine in DMF-d<sub>7</sub> with 0, 5 and 10 equiv of dimethyl trisulfide (DMTS) as HCN scavenger. The formation of HCN and rate of amidation was monitored by <sup>1</sup>H NMR, revealing that DMTS scavenges HCN without inhibiting the rate of amidation. DIC/Oxyma mediated amidations of Fmoc‑Ser(<i>t</i>‑Bu)‑OH with (S)-(‑)-1-phenylethylamine in DMF and NBP/EtOAc (1:4) with and without 10 equiv of DMTS were carried out and found to be comparable.</p>

Recent Advances on C-Se Bond-forming Reactions at Low and Room Temperature

2020 ◽  
Vol 23 (28) ◽  
pp. 3206-3225 ◽  
Author(s):  
Amol D. Sonawane ◽  
Mamoru Koketsu
Keyword(s):  
Room Temperature ◽  
Bond Formation ◽  
Bond Forming ◽  
Material Chemistry ◽  
Recent Advances ◽  
Bond Forming Reactions ◽  
Bond Formation Reactions

: Over the last decades, many methods have been reported for the synthesis of selenium- heterocyclic scaffolds because of their interesting reactivities and applications in the medicinal as well as in the material chemistry. This review describes the recent numerous useful methodologies on C-Se bond formation reactions which were basically carried out at low and room temperature.

Graphene Oxide and Its Derivatives: Their Synthesis and Use in Organic Synthesis

2019 ◽  
Vol 23 (2) ◽  
pp. 188-204 ◽  
Author(s):  
Xiangjun Peng ◽  
Xianyun Xu ◽  
Fujiang Huang ◽  
Qian Liu ◽  
Liangxian Liu
Keyword(s):  
Graphene Oxide ◽  
Carbon Materials ◽  
Device Fabrication ◽  
Organic Reactions ◽  
Bond Forming ◽  
Bond Forming Reactions ◽  
Modern Physics ◽  
Recent Developments ◽  
Optical And Mechanical Properties ◽  
Nitrogen Double Bond

Since Geim and co-workers reported their groundbreaking experiments on graphene, research on graphene oxide (GO) and its derivatives has greatly influenced the field of modern physics, chemistry, device fabrication, material science, and nanotechnology. The unique structure and fascinating properties of these carbon materials can be ascribed to their eminent chemical, electronic, electrochemical, optical, and mechanical properties of GO and its derivatives, particularly compared to other carbon allotropes. The present Review aims to provide an overview on the recent developments in the preparation of GO and its derivatives and their applications in organic reactions. We will first outline the synthesis of GO and its derivatives. Then, we will discuss the major sections about their application as stoichiometric and catalytic oxidants in organic reactions, a particular emphasis on the carbon-carbon, carbon-oxygen, and carbon-nitrogen single bond-forming reactions, as well as carbon-oxygen and carbon-nitrogen double bond-forming reactions. Simultaneously, this Review also describes briefly transition metal supported on GO or its derivatives as a catalyst for organic reaction. Lastly, we will present an outlook of potential areas where GO and its derivatives may be expected to find utility or opportunity for further growth and study.

Concise Total Synthesis of Curvulone B

Synlett ◽  
2020 ◽  
Author(s):  
Debendra K. Mohapatra ◽  
Shivalal Banoth ◽  
Utkal Mani Choudhury ◽  
Kanakaraju Marumudi ◽  
Ajit C. Kunwar
Keyword(s):  
Total Synthesis ◽  
Stereoselective Synthesis ◽  
Ring System ◽  
Bond Forming ◽  
Cross Metathesis ◽  
Bond Forming Reactions ◽  
Key Steps

AbstractA concise and convergent stereoselective synthesis of curvulone B is described. The synthesis utilized a tandem isomerization followed by C–O and C–C bond-forming reactions following Mukaiyama-type aldol conditions for the construction of the trans-2,6-disubstituted dihydropyran ring system as the key steps. Other important features of this synthesis are a cross-metathesis, epimerization, and Friedel–Crafts acylation.

scholarly journals Borane Catalysed Cyclopropenation of Arylacetylenes

2021 ◽  
Author(s):  
Katarina Stefkova ◽  
Matthew Heard ◽  
Ayan Dasgupta ◽  
Rebecca Melen
Keyword(s):  
Catalytic Activities ◽  
Bond Forming ◽  
Bond Forming Reactions

Triarylboranes have gained substantial attention as catalysts for C–C bond forming reactions due to their remarkable catalytic activities. Herein, we report B(C6F5)3 catalysed cyclopropenation of a wide variety of arylacetylenes...

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