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In organic chemistry, the ene reaction (also known as the Alder-ene reaction by its discoverer Kurt Alder in 1943) is a chemical reaction between an alkene with an allylic hydrogen (the ene) and a compound containing a multiple bond (the enophile), in order to form a new σ-bond with migration of the ene double bond and 1,5 hydrogen shift.
The ene reaction is one of the most common forms of group transfer reactions, where an allylic hydrogen is transferred to an alkene in a cyclic concerted mechanism. The ene reaction is further divided into subgroups including intramolecular ene, metallo-ene, and carbonyl ene reactions. [ 8 ]
The metal-mediated processes include a carbonyl-olefination and an olefin–olefin metathesis event. There are two general mechanistic schemes to perform this overall transformation: one, reaction of a [M=CHR 1] reagent with an alkene to generate a new metal alkylidene, which then couples with a carbonyl group to form the desired substituted alkene and an inactive [M=O] species (type A); two ...
The Riley Oxidation is amenable to a variety of carbonyl and olefinic systems with a high degree of regiocontrol based on the substitution pattern of the given system. Ketones with two available α-methylene positions react more quickly at the least hindered position.: [ 1 ]
Such reaction proceed with retention of stereochemistry. The rates are sensitive to electron-withdrawing or electron-donating substituents. When irradiated by UV-light, alkenes dimerize to give cyclobutanes. [20] Another example is the Schenck ene reaction, in which singlet oxygen reacts with an allylic structure to give a transposed allyl ...
In organic chemistry, the Conia-ene reaction is an intramolecular cyclization reaction between an enolizable carbonyl such as an ester or ketone and an alkyne or alkene, giving a cyclic product with a new carbon-carbon bond.
The term enol is an abbreviation of alkenol, a portmanteau deriving from "-ene"/"alkene" and the "-ol". Many kinds of enols are known. [1] Keto–enol tautomerism refers to a chemical equilibrium between a "keto" form (a carbonyl, named for the common ketone case) and an enol.
The Koch reaction is a special case of hydrocarboxylation reaction that does not rely on metal catalysts. Instead, the process is catalyzed by strong acids such as sulfuric acid or the combination of phosphoric acid and boron trifluoride. The reaction is less applicable to simple alkene.