نتایج جستجو برای: nucleophile
تعداد نتایج: 1574 فیلتر نتایج به سال:
We report a desymmetrization of cyclohexadienones by intramolecular conjugate addition of a tethered dithiane nucleophile. Mild reaction conditions allow the formation of diversely functionalized fused bicyclic lactones. The products participate in facially selective additions from the convex surface, leading to allylic alcohol derivatives.
Abstract A new easy‐to‐synthesize solid supported Eosin Y and its application in the building of a catalytic continuous flow reactor is reported. The fluidic device was employed to perform tertiary amines in‐flow photooxidations followed by nucleophile addition, with overall productivity increased one order magnitude. When using iminium‐ions situ generated or telescoped fashion, resulting Manni...
In nucleophilic aromatic photosubstitution, just as in aromatic substitution in the ground state, substituents can have directing and activating effects. Four rules, which describe orientation of nucleophilic substitution in the excited state, can now be formulated. They are: (a) meta-activation by the nitro group (b) ortho/para-activation by the methoxy group (and probably also by other electr...
C3–N1′ bond formation of bisindoles has been a great challenge due to the intrinsic reactivity indoles as both C3 and N1-nucleophilic character. Herein, we demonstrate an cross-coupling reaction using N-methoxyindoles N-electrophilic indole reagents in presence Lewis acid. The generated this transformation are latent C3-nucleophile, allowing them be used strategic intermediates sequential C3–N1...
Penicillin acylase catalyses the hydrolysis and synthesis of semisynthetic beta-lactam antibiotics via formation of a covalent acyl-enzyme intermediate. The kinetic and mechanistic aspects of these reactions were studied. Stopped-flow experiments with the penicillin and ampicillin analogues 2-nitro-5-phenylacetoxy-benzoic acid (NIPAOB) and d-2-nitro-5-[(phenylglycyl)amino]-benzoic acid (NIPGB) ...
An enantioselective dearomatization of isoquinolines has been developed using chiral anion-binding catalysis. This transformation, catalyzed by a simple and easy to prepare tert-leucine-based thiourea derivative, makes use of silyl phosphite as a nucleophile and generates cyclic α-aminophosphonates. This is the first time asymmetric anion-binding catalysis has been applied to the synthesis of α...
Novel, diverse pyrido [2,3-d] pyrimidine and pyrimido [4,5-d] pyrimidine analogs were synthesized by the reaction of 1,3-substituted-5-cyano uracil derivatives with appropriate nucleophile under mild conditions. Utilising 5-cyano uracil with various substitutions as a substrate leads to rapid synthesis of annulated uracils with diverse biological properties.
In this Communication, we report a system in which an achiral Lewis acid (activating the diene) works in concert with a chiral nucleophile (dienophile) to effect the first highly enantio- and regioselective catalytic inverse electron demand Diels-Alder [4 + 2] cycloaddition reaction to form biologically active quinoxalinones from ketene enolates and o-benzoquinone diimides in good to excellent ...
A catalytic method has been developed for construction of indoline-2-thiones containing an all-carbon quaternary centre at the C-3 position. Successive treatment of α,β-unsaturated aldehydes bearing an isothiocyanato moiety with an in situ generated N-heterocyclic carbene and an appropriate heteroatomic nucleophile provided the 3,3-disubstituted indoline derivatives in moderate to good yields.
A novel and efficient route for the preparation of quinazolin-4(3H)-imines via a palladium-catalyzed three-component reaction of carbodiimide, isocyanide, and nucleophile is described. The palladium-catalyzed isocyanide insertion is believed to be the key step during the reaction process.
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