Peptide macrocyclization is often a slow process, plagued by epimerization and cyclodimerization. Herein, we describe a new method for peptide macrocyclization employing the AgI‐promoted transformation of peptide thioamides. The AgI has a dual function: chemoselectively activating the thioamide and tethering the N‐terminal thioamide to the C‐terminal carboxylate. Extrusion of Ag2S generates an isoimide intermediate, which undergoes acyl transfer to generate the native cyclic peptide, resulting in a rapid, traceless macrocylization process. Cyclic peptides are furnished in high yields within 1 hour, free of epimerization and cyclodimerization. 相似文献
A novel one-pot synthesis of four new classes of amidothiophosphoric esters and trisamidothiophosphoric esters is developed. (1-Alkyl-2-pyrimidinylidenamido)bis(diethylamido)thiophosphates, (1-alkyl-2-pyrimidinylidenamido)bis (O-2/4-methylphenyl)thiophosphates, (3-alkyl-2-thiazolinylidenamido)bis (diethylamido)thiophosphate and (3-alkyl-2-thiazolinylidenamido)bis(O-2/4-methylphenyl)thiophosphates are obtained from the nucleophilic substitution and oxidation of N-alkyl-2-cycloiminylidenaminodichlorophosphines generated in situ from the reaction of the corresponding N-alkyl-2-aminocycloiminium halide with phosphorus trichloride and triethylamine. The synthesized thiophosphoric esters have been investigated for fungicidal properties. 相似文献
This study aimed to investigate the antioxidant, anti-inflammatory and biosorption properties of starch nanocrystals (SNC). The characterization of synthesized SNC was done using various analytical techniques like microscopic and spectroscopic analysis. The antioxidant property was determined using DPPH (2,2-diphenyl-1-picrylhydrazyl) assay and metal ion chelating assay. SNC showed the highest scavenging activity of 70.03?±?0.74% at 100 µg/mL concentration. Protein denaturation assay and proteinase inhibitory assay depicted the anti-inflammatory property of SNC. The results revealed that the maximum inhibition activity was found at 100 µg/mL with 72.71% inhibition. The maximum removal efficiency was found to be 83.42% at pH 2.0 with 0.15 g biosorbent. As the pH increases, biosorption capacity of SNC were reduced from 8.17 to 6.30 mg/g and the efficiency of the dye removal was decreased from 80.95 to 36.01%. The shape of synthesized SNC was spherical nanoplatelets and it shows agglomeration. The Langmuir isotherm model is best suited for the biosorption experiments with the R2 value of 0.986. SNC were subjected to cytotoxic and phytotoxic evaluation. Cell viability and phytotoxic assays proves the non-toxic nature of the SNC.
Benzothiazepine, a prominent “drug prejudice core”, is a heterocyclic moiety of immense importance due to its presence in a wide range of bioactive compounds. They act as a primary “biolinker” in diverse synthetic routes to obtain bioactive molecules and serve as important templates in synthetic and medicinal chemistry. They are known to possess a plethora of pharmacological activities, which include Ca2+ channel blockers, CNS acting agents, anti-HIV, ACE inhibitors, antimicrobial, antifungal, anticancer. Their promising behaviour as drug molecules led the scientific community to develop novel, mild, green, and highly efficient synthetic routes for their synthesis. The conventional synthesis generally involved the condensation of chalcones with 2-aminothiophenol in the presence of acid/base with high-temperature heating, mostly resulting in poor yields or mixtures. However, recent trends are replacing these conditions with mild and green conditions through organocatalysis or other methodologies. In this review, an attempt has been made by authors to summarize (a) Recent developments in the synthetic strategies of 1,5-benzoathiazepines and its derivatives (b) Conventional methods for the synthesis of 1,5-benzothiazepines including progress in the green chemistry routes (c) Applications of various metals and organocatalysts to achieve the enantioselective synthesis of title compounds. 相似文献
We report on attempts towards the synthesis of titanium nanoparticles using a wet chemical approach in imidazolium-based ionic
liquids (ILs) under reducing conditions. Transmission electron microscopy finds nanoparticles in all cases. UV/Vis spectroscopy
confirms the nanoparticulate nature of the precipitate, as in all cases an absorption band between ca. 280 and 300 nm is visible.
IR spectroscopy shows that even after extensive washing and drying, some IL remains adsorbed on the nanoparticles. Raman spectroscopy
suggests the formation of anatase nanoparticles, but X-ray diffraction reveals that, possibly, amorphous titania forms or
that the nanoparticles are so small that a clear structure assignment is not possible. The report thus shows that (possibly
amorphous) titanium oxides even form under reducing conditions and that the chemical synthesis of titanium nanoparticles in
ILs remains elusive. 相似文献
Designs, Codes and Cryptography - Let $${\mathbb {F}}_q$$ denote the finite field of order q, and let $$n = m_1+m_2+\cdots +m_\ell ,$$ where $$m_1,m_2,\ldots ,m_\ell $$ are arbitrary... 相似文献