[GRAPHICS] Photoinduced reactions of 1-acetylisatin 1 with diphenylacetylenes 2a-2c afforded the corresponding 3-methylene-2-indolones 4a-4e and 5a-5e in 80-90% yields via a spirooxetene intermediate, Similar irradiat...
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[GRAPHICS] Photoinduced reactions of 1-acetylisatin 1 with diphenylacetylenes 2a-2c afforded the corresponding 3-methylene-2-indolones 4a-4e and 5a-5e in 80-90% yields via a spirooxetene intermediate, Similar irradiation of 1 with phenylacetylene, on the other hand, resulted in efficient formation of two diastereoisomeric dispiro[3H-indole-3,2'-furan-3',3"-(3H)-indole]-2,5',2"(2H,5'H,2"H)triones 6 and 7 via a reaction sequence with initial formation of the spirooxetene intermediate. The regioselectivity in the photocycloaddition of 1 with phenylacetylene and the reaction mechanism for the formation of 6 and 7 are discussed.
Das durch Addition von 2‐Mercaptoäthanol an Acetylendicarbonsäuredimethylester entstehende cis‐configurierte Addukt reagiert in Xylol bei baisischer Katalyse mit Natriumhydrid unter Ringschluß zu eine...
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Das durch Addition von 2‐Mercaptoäthanol an Acetylendicarbonsäuredimethylester entstehende cis‐configurierte Addukt reagiert in Xylol bei baisischer Katalyse mit Natriumhydrid unter Ringschluß zu einem Tetrahydro‐[1.4]‐oxathiin. Dieses setzt sich unter Stickstoff mit β‐Amino‐äthyl‐mercaptan bei stark basischer Katalyse zu einem Tetrahydro‐[1.4]‐thiazin um. Synthesis of the 2,3,5,6‐Tetrahydro‐1,4‐oxathiine‐Ring form Dimethyl Acetylenedicarboxylate The cis‐configurated reaction product from the addition of 2‐mercaptoethanol to dimethyl acetylenedicarboxylate reacts in xylene with the catalytic action of sodium hydride by ring closure to a tetrahydro‐1.4‐oxathiine. This compound, in the presence of a strong basic catalyst and in protective atmosphere of nitrogen, is converted by β‐amino‐ethylmercaptan into a tetrahydro‐1.4‐thiazine.
The increased resistance of various bacteria toward available antibiotic drugs has initiated intensive research efforts into identifying new sources of antimicrobial substances. Short antibiotic peptides (10–30 resid...
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The increased resistance of various bacteria toward available antibiotic drugs has initiated intensive research efforts into identifying new sources of antimicrobial substances. Short antibiotic peptides (10–30 residues) are prevalent in nature as part of the intrinsic defense mechanisms of most organisms and have been proposed as a blueprint for the design of novel antimicrobial agents^1. Antimicrobial peptides are generally believed to kill bacteria through membrane permeabilization and extensive pore-formation^1. Assays providing rapid and easy evaluation of interactions between antimicrobial membrane peptides and lipid bilayers could significantly improve screening for substances with effective antibacterial properties, as well as contribute to the elucidation of structural and functional properties of antimicrobial peptides. Here we describe a colorimetric sensor in which particles composed of phospholipids and polymerized polydiacetylene (PDA) lipids were shown to exhibit striking color changes upon interactions with antimicrobial membrane peptides. The color changes in the system occur because of the structural perturbation of the lipids following their interactions with antimicrobial peptides. The assay was also sensitive to the antibacterial properties of structurally and functionally related peptide analogs.
An efficient route toward the synthesis of unsaturated (bis-diacetylenic) and saturated 40- and 48-membered macrocyclic bisphosphocholines has been developed using 2-phenyl-5-hydroxy-1,3-dioxane as a common glycerol s...
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An efficient route toward the synthesis of unsaturated (bis-diacetylenic) and saturated 40- and 48-membered macrocyclic bisphosphocholines has been developed using 2-phenyl-5-hydroxy-1,3-dioxane as a common glycerol synthon. Ring closure was accomplished using either high dilution Glaser oxidation or [(Cy3P)(2)Ru=CHPh]Cl-2-catalyzed olefin metathesis conditions. Deprotection of benzyl ethers using trimethyisilyl iodide (TMS I) in the presence of diacetylenic moieties has also been demonstrated for the first time.
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