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A [3+2]-cycloaddition with the alkene (3) gives the cyclic intermediate 4. [ 9 ] [ 10 ] Basic hydrolysis liberates the diol ( 5 ) and the reduced osmate ( 6 ). Methanesulfonamide (CH 3 SO 2 NH 2 ) has been identified as a catalyst to accelerate this step of the catalytic cycle and if frequently used as an additive to allow non-terminal alkene ...
In organic chemistry, alkylidene is a general term for divalent functional groups of the form R 2 C=, where each R is an alkane or hydrogen. [1] They can be considered the functional group corresponding to mono- or disubstituted divalent carbenes (known as alkylidenes), [2] or as the result of removing two hydrogen atoms from the same carbon atom in an alkane.
The reverse or retro-Cope elimination has been reported, in which an N,N-disubstituted hydroxylamine reacts with an alkene to form a tertiary N-oxide. [9] [10] The reaction is a form of hydroamination and can be extended to the use of unsubstituted hydroxylamine, in which case oximes are produced. [11]
Reduction of alkynes is a useful method for the stereoselective synthesis of disubstituted alkenes. If the cis -alkene is desired, hydrogenation in the presence of Lindlar's catalyst (a heterogeneous catalyst that consists of palladium deposited on calcium carbonate and treated with various forms of lead) is commonly used, though hydroboration ...
The Heck reaction is the palladium-catalyzed coupling of an aryl or alkenyl halide with an alkene to form a substituted alkene. [2] Intramolecular variants of the reaction may be used to generate cyclic products containing endo or exo double bonds.
Hydroboration of 1,2-disubstituted alkenes, such as a cis or trans olefin, produces generally a mixture of the two organoboranes of comparable amounts, even if the steric properties of the substituents are very different. For such 1,2-disubstituted olefins, regioselectivity can be observed only when one of the two substituents is a phenyl ring.
Strained cyclooctenes and other activated alkenes react with tetrazines in an inverse electron-demand Diels-Alder followed by a retro [4+2] cycloaddition (see figure). [41] Like the other reactions of the trans-cyclooctene, ring strain release is a driving force for this reaction.
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).