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The reaction mechanism for an alkene bromination can be described as follows. In the first step of the reaction, a bromine molecule approaches the electron-rich alkene carbon–carbon double bond. The bromine atom closer to the bond takes on a partial positive charge as its electrons are repelled by the electrons of the double bond.
Dihydroxylation is the process by which an alkene is converted into a vicinal diol. Although there are many routes to accomplish this oxidation, the most common and direct processes use a high-oxidation-state transition metal (typically osmium or manganese). The metal is often used as a catalyst, with some other stoichiometric oxidant present. [1]
The Upjohn dihydroxylation is an organic reaction which converts an alkene to a cis vicinal diol. It was developed by V. VanRheenen, R. C. Kelly and D. Y. Cha of the Upjohn Company in 1976. [1] It is a catalytic system using N-methylmorpholine N-oxide (NMO) as stoichiometric re-oxidant for the osmium tetroxide. It is superior to previous ...
Such reactions give alkenes in the case of vicinal alkyl dihalides: [2] R 2 C(X)C(X)R 2 + M → R 2 C=CR 2 + MX 2. Most desirable from the perspective of remediation are dehalogenations by hydrogenolysis, i.e. the replacement of a C−X bond by a C−H bond. Such reactions are amenable to catalysis: R−X + H 2 → R−H + HX
In the example shown below, the para-methoxybenzoyl substituent serves primarily as a source of steric bulk to allow the catalyst to differentiate the two faces of the alkene. [23] SAD scheme 3. It is often difficult to obtain high diastereoselectivity on cis-disubstituted alkenes when both ends of the olefin have similar steric environments.
The Sharpless oxyamination (often known as Sharpless aminohydroxylation) is the chemical reaction that converts an alkene to a vicinal amino alcohol.The reaction is related to the Sharpless dihydroxylation, which converts alkenes to vicinal diols. [1]
The Milas hydroxylation is an organic reaction converting an alkene to a vicinal diol, and was developed by Nicholas A. Milas in the 1930s. [1] [2] The cis-diol is formed by reaction of alkenes with hydrogen peroxide and either ultraviolet light or a catalytic osmium tetroxide, [3] vanadium pentoxide, or chromium trioxide.
Vicinal difunctionalization refers to a chemical reaction involving transformations at two adjacent centers (most commonly carbons). This transformation can be accomplished in α,β-unsaturated carbonyl compounds via the conjugate addition of a nucleophile to the β-position followed by trapping of the resulting enolate with an electrophile at the α-position.