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Arrow pushing or electron pushing is a technique used to describe the progression of organic chemistry reaction mechanisms. [1] It was first developed by Sir Robert Robinson.In using arrow pushing, "curved arrows" or "curly arrows" are drawn on the structural formulae of reactants in a chemical equation to show the reaction mechanism.
The synthesis of epoxides via this method serves as an important retrosynthetic alternative to the traditional epoxidation reactions of olefins. Johnson–Corey–Chaykovsky Reaction. The reaction is most often employed for epoxidation via methylene transfer, and to this end has been used in several notable total syntheses (See Synthesis of ...
The reaction is highly stereospecific in the sense that the double bond stereochemistry is generally transferred to the relative configuration of the epoxide with essentially perfect fidelity, so that a trans-olefin leads to the stereoselective formation of the trans-2,3-substituted epoxide only, as illustrated by the example above, while a cis ...
Mechanisms for formations of the carbonyl products. The epoxide product is formed by an intramolecular addition reaction in which a lone pair from the oxygen attacks the carbocation (6). Mechanism for the formation of the epoxide product. This reaction is exothermic due to the stability of nitrogen gas and the carbonyl containing compounds.
Curved-arrow mechanism for the oxymercuration reaction. Regioselectivity and stereochemistry. Oxymercuration is very regioselective and is a textbook Markovnikov ...
Other processes may take place competitively under basic conditions, particularly when β-elimination is slow or not possible. [6] These pathways likely begin with lithiation of a carbon in the epoxide ring, followed by α-elimination to afford a carbene intermediate. 1,2-hydrogen migration leads to ketones, [2] while intramolecular C–H insertion affords cyclic alcohols with the formation of ...
Dioxiranes are electrophilic oxidants that react more quickly with electron-rich than electron-poor double bonds; however, both classes of substrates can be epoxidized within a reasonable time frame. The mechanism of epoxidation with dioxiranes likely involves concerted oxygen transfer through a spiro transition state. As oxygen transfer occurs ...
The Juliá–Colonna epoxidation is an asymmetric poly-leucine catalyzed nucleophilic epoxidation of electron deficient olefins in a triphasic system.The reaction was reported by Sebastian Juliá at the Chemical Institute of Sarriá in 1980, [1] with further elaboration by both Juliá and Stefano Colonna (Istituto di Chimica Industriale dell'Università, Milan, Italy).