Electrophilic addition hydroxylation

Electrophilic addition to die alkene with the formation of a 5-membered ring occurs on anodic oxidation of 44 [150]. Reaction of the intermediate delocalised carbonium ion with the adjacent hydroxyl function in 45 also results in the formation of a 5-merabered ring [151],... 

Specifically, hydroxyl radicals can oxidize organics by hydroxylation, hydrogen abstraction, electrophilic addition, and electron transfer, depending upon the nature of organic compounds. 

Electrophilic addition of hydroxyl radicals to organic n systems will lead to organic radicals, as shown in the following equation ... 

When hydrogen abstraction or electrophilic addition reactions may be inhibited by multiple halogen substitutions or steric hindrance, a hydroxyl radical can be reduced to a hydroxide anion by an organic substrate shown in Equation (7.28) ... 

The oxidation of organic compounds by hydroxyl radicals follows the same reaction through hydrogen abstraction or electrophilic addition, depending upon the nature of the organic compound ... 

Alkenes get converted to alcohols by treatment with aqueous acid (sulphuric or phosphoric acid (Following fig.)). This electrophilic addition reaction involves the addition of water across the double bond. The hydrogen adds to one carbon while a hydroxyl group adds to the other carbon. 

Phenol complexes of [Os] display pronounced reactivity toward Michael acceptors under very mild conditions. The reactivity is due, in part, to the acidity of the hydroxyl proton, which can be easily removed to generate an extended enolate. Reactions of [Os]-phenol complexes are therefore typically catalyzed using amine bases rather than Lewis acids. The regio-chemistry of addition to C4-substituted phenol complexes is dependent upon the reaction conditions. Reactions that proceed under kinetic control typically lead to addition of the electrophile at C4. In reactions that are under thermodynamic control, the electrophile is added at C2. These C2-selective reactions have, in some cases, allowed the isolation of o-quinone methide complexes. As with other [Os] systems, electrophilic additions to phenol complexes occur anti to the face involved in metal coordination. 

Electrophilic addition. The examples available succeed by virtue of functionality placed near the reacting center. In the instances illustrated (Figure 2) the hydroxyl group of an allylic alcohol participates intimately with the electrophilic species to provide an ability to discriminate the faces of a double bond (24 2 5). The latter reaction was employed in a sequence eventuating in the sex pheromone of the gypsy moth, disparlure. 

This is ordinary electrophilic addition, with rate-determining protonation as the first step. Certain other alkynes have also been hydrated to ketones with strong acids in the absence of mercuric salts. Simple alkynes can also be converted to ketones by heating with formic acid, without a catalyst.Lactones have been prepared from trimethylsilyl alkenes containing an hydroxyl unit elsewhere in the molecule, when reacted with molecular oxygen, CuCla, and a palladium catalyst. ... 

Figure 3. The nitrocresol isomers considered in this study and the sites that are activated by the hydroxyl group ( ) and methyl group (°) toward electrophilic addition.

Other applications of Evans oxazolidinones include alkylation, Diels-Alder cycloaddition, Michael addition, and electrophilic halogenation, hydroxylation, and amination reactions [15]. In all cases, the conformational rigidity of the reaction TS allows the substituents at the stereocenters to direct efficiently the reaction course. 

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