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Others, however, insist that such a usage is an abuse of terminology, and limit the Michael addition to the formation of carbon–carbon bonds through the addition of carbon nucleophiles. The terms oxa-Michael reaction and aza-Michael reaction [2] have been used to refer to the 1,4-addition of oxygen and nitrogen nucleophiles, respectively. The ...
To manufacture a polyaspartic ester, an amine is reacted with dialkyl maleate by the aza-Michael reaction. [8]Diethyl maleate is the usual maleate used. This converts the primary amines to secondary amines and also introduces bulky groups to the molecule which causes steric hindrance, slowing the reaction down.
Two common modes of Lewis acid catalysis in reactions with polar mechanisms. In reactions with polar mechanisms, Lewis acid catalysis often involves binding of the catalyst to Lewis basic heteroatoms and withdrawing electron density, which in turn facilitates heterolytic bond cleavage (in the case of Friedel-Crafts reaction) or directly activates the substrate toward nucleophilic attack (in ...
The quinidine-derived bifunctional organocatalyst 63 (first reported by Deng and co-workers) acts as a proficient catalyst for Michael addition reactions. [28] In this organocatalytic system, the H-bonding interaction arising from the quinoline alcohol is thought to be crucial for achieving high enantioselectivities.
One of the main advantages of hydrogen-bond catalysis is the ability to construct catalysts that engage in multiple non-covalent interactions to promote the reaction. In addition to using hydrogen-bond donors to activate or stabilize a reactive center during the reaction, it is possible to introduce other functional groups, such as Lewis bases ...
The Shi epoxidation is a chemical reaction described as the asymmetric epoxidation of alkenes with oxone (potassium peroxymonosulfate) and a fructose-derived catalyst (1). This reaction is thought to proceed via a dioxirane intermediate, generated from the catalyst ketone by oxone (potassium peroxymonosulfate). The addition of the sulfate group ...
The Knorr pyrrole synthesis is a widely used chemical reaction that synthesizes substituted pyrroles (3). [1] [2] [3] The method involves the reaction of an α-amino-ketone (1) and a compound containing an electron-withdrawing group (e.g. an ester as shown) α to a carbonyl group (2). [4] The Knorr pyrrole synthesis
Heterogeneous catalysts are easily removed from a reaction mixture by filtration. Although some amount of metal catalyst typically remains in the product from leaching, these amounts tend to be lower than those remaining after workup of a homogenous metal-catalyzed cross-coupling. [1]