نتایج جستجو برای: protected α
تعداد نتایج: 218898 فیلتر نتایج به سال:
Peptidomimetics based on hydrazino derivatives of α-amino acids represent an important class of peptidic foldamers with promising biological activities, like protease inhibition and antimicrobial activity. However, the lack of straightforward method for the synthesis of optically pure hydrazino acids and efficient incorporation of hydrazino building blocks into peptide sequence hamper wider exp...
The three-component Petasis borono-Mannich reaction starting with easily accessible N-protected α-amino aldehydes produces efficiently and diastereoselectively 1,2-trans-diamines with an enantiomeric excess of up to 98%.
The aggregation of α-synuclein is one on the key pathogenic events in Parkinson's disease. In the present study, we investigated the inhibitory capacities of stilbenes against α-synuclein aggregation and toxicity. Thioflavin T fluorescence, transmission electronic microscopy, and SDS-PAGE analysis were performed to investigate the inhibitory effects of three stilbenes against α-synuclein aggreg...
The endotoxic portion of lipopolysaccharide (LPS), a glycophospholipid Lipid A, initiates the activation of the Toll-like Receptor 4 (TLR4)-myeloid differentiation factor 2 (MD-2) complex, which results in pro-inflammatory immune signaling. To unveil the structural requirements for TLR4·MD-2-specific ligands, we have developed conformationally restricted Lipid A mimetics wherein the flexible βG...
Enantiomerically pure mono-N-Boc-protected trans-cyclohexane-1,2-diamines are used as organocatalysts for the enantioselective conjugate addition of α,α-disubstituted aldehydes to maleimides. Using a single enantiomer of the organocatalyst, both enantiomeric forms of the resulting Michael adducts bearing a new quaternary stereocenter are obtained in high yields, only by changing the reaction so...
Efficient bismuthand iron-catalyzed three-component syntheses of α-arylglycines have been developed. These methods provide a general, atom-economic route to various N-protected α-arylglycines starting from readily available amides (or carbamates), glyoxalates, and (hetero)arenes with water as the only by-product. Scope and limitations of bismuthand iron-catalyzed reactions are discussed and com...
Two routes to the 2,6-dideoxysugar methyl trioxacarcinoside A are described. Each was enabled by an apparent α-chelation-controlled addition of an allylmetal reagent to a ketone substrate containing a free α-hydroxyl group and a β-hydroxyl substituent, either free or protected as the corresponding di-tert-butylmethyl silyl ether. Both routes provide practical access to gram quantities of trioxa...
Based on a preactivation protocol with (p-Tol)2SO/Tf2O, a practical, straightforward, and high-yielding synthesis of α-sialyl C-glycosides was accomplished by coupling N-acetyl-5-N,4-O-oxazolidione protected thiosialoside with various trimethylsilyl enol ethers and allyltrimethylsilanes. High yields and excellent α-selectivities were obtained for the strong π-nucleophiles with large nucleophili...
A variety of chiral N-phosphinyl α-imino esters have been synthesized for the first time from ketoesters and phosphinylamide, which were then reduced by L-selectride to give the corresponding N-phosphinyl-protected α-amino esters. The reduction proceeded very well with excellent chemical yields (88-98%) as well as high diastereoselectivities (96:4 to 99:1). Some of these products could be obtai...
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