نتایج جستجو برای: electrophilic coupling agent
تعداد نتایج: 405108 فیلتر نتایج به سال:
agent technology is an emerging and promising research area in software technology, which increasingly contributes to the development of value-added information systems for large healthcare organizations due to its capability to automatically modify themselves in response to changes in their operating environment. multi agent system (mas) approach is the construction of a complex system as a se...
Benzyltriphenylphosphonium bromide (BTPB) has been applied as an efficient catalyst for the preparation of bis(indolyl)methanes (BIMs) via electrophilic substitution of indoles with aldehydes in the absence of solvent.
Although visible light photoredox catalysis has emerged as a powerful tool for the construction of C–C bonds, common catalysts and/or their photoexcited states suffer from low redox potentials, limiting their applicability to alkyl radical generation from substrates with activated carbon–halogen bonds. Radicals derived from these activated compounds, being highly electrophilic or stabilized, do...
Conjugation to folic acid is known to enhance the uptake of molecules by human cells that over-produce folate receptors. Variants of bovine pancreatic ribonuclease (RNase A) that have attenuated affinity for the endogenous ribonuclease inhibitor protein (RI) are toxic to mammalian cells. Here, the random acylation of amino groups in wild-type RNase A with folic acid is shown to decrease its cat...
A novel class of dibenzo-fused 1,9-diaza-9a-boraphenalenes featuring zigzag edges with a nitrogen-boron-nitrogen bonding pattern named NBN-dibenzophenalenes (NBN-DBPs) has been synthesized. Alternating nitrogen and boron atoms impart high chemical stability to these zigzag-edged polycyclic aromatic hydrocarbons (PAHs), and this motif even allows for postsynthetic modifications, as demonstrated ...
this study describes the organic synthesis of 5-(2-amimo-4-styryl pyrimidine-4-yl)-4-methoxy benzofuran-6-ol (spbf) as an example of a benzofuran derivative used as a new series of amyloid imaging agents. these benzofuran derivatives may be useful amyloid imaging agents for detecting b-amyloid plagues in the brain of alzheimer’s disease. the precursor is 1-[6-hydroxy-4-methoxybenzofuran-5-yl]-p...
A three-component coupling of vinyl triflates and boronic acids to alkenes catalyzed by palladium is reported. Using 1,3-dienes, selective 1,2-alkene difunctionalization is observed, whereas the use of terminal alkenes results in 1,1-alkene difunctionalization. The reaction outcome is attributed to the formation of stabilized, cationic Pdπ-allyl intermediates to regulate β-hydride elimination. ...
A concise synthesis of the biologically active alkaloid berberine is reported, and a versatile palladium-catalyzed enolate arylation is used to form the isoquinoline core. The overall yield of 50 % is a large improvement over the single, previous synthesis. By design, this modular route allows the rapid synthesis of other members of the protoberberine family (e.g., pseudocoptisine and palmatine...
The development of highly efficient amide bond forming methods which are devoid of side reactions, including epimerization, is important, and such a method is described herein and is based on the concept of rapid and strong activation of carboxylic acids. Various carboxylic acids are rapidly (0.5 s) converted into highly active species, derived from the inexpensive and less-toxic solid triphosg...
Modulation of the N-azo coupling between ring-substituted arenediazonium chlorides and premixed methylamine-formaldehyde leads not only to 1-aryl-3-hydroxymethyl-3-methyltriazenes and their dimers, but also to unexpected cyclic and complex products. The syntheses comprise reactions with arenediazonium chlorides bearing both -M and +M substituents at para and ortho/para positions of the phenyl r...
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