Catechols brominated

Action of bromine water. To a concentrated aqueous solution of the phenol or to the phenol itself, add bromine water gradually. At first the bromine is decolorised and then on adding an excess a white or yellowish-white precipitate of a polybromo-derivative is produced with all except catechol, hydroquinone, i- and 2 naphthol. 

On adding i drop of bromine water to catechol, a deep red coloration is produced immediately. On gradually adding bromine water to a solution of hydroquinone, a deep red coloration is produced, followed by the separation of deep green crystals which then dissolve giving a yellow solution, i- and 2-Naphthol will decolorise hromine water, but usually no precipitate of the bromo compound can be obtained. 

The best yield I ve achieved is 84g of benzodioxole from 110 of catechol. And to progress from here you ll probably need to do this reaction twice to get enough benzodioxole for the bromination."... 

Azaloxan (12) is an antidepressant agent. Its synthesis can be accomplished starting with the reaction of catechol (7) and 3,4-dibromobutyronitrile (obtained by addition of bromine to the olefin) to give l,4-benzodioxan-2-ylacetonitrile (8). A series of functional group transformations ensues [hydrolysis to the acid (9), reduction to the alcohol (10) and conversion to a tosylate (11)] culminating in an SN-2 displacement reaction on tosylate 11 with l-(4-piperidinyl)-2-imidazolidi-none to give azaloxan (12) [3]. 

Carbon monoxide, 57, 11 Carbonyl compounds, 56, 36 Carboxylic acids, a-bromination of, 55, 31 CARBOXYLIC ACID CHLORIDES, ketones from, 55, 122 CARBYLAMINE REACTION, 55, 96 Carcinogens, list of. 56, 128 58, 168 Carveol, 56, 106 Carveol acetate, 56, 106 Catechols, 58, 125... 

Bromine Catechol Ally I cyanide Sulfuric acid 4-Aminopyridine Hydrogen Furmaric acid... 

A biomimetic catechol cleavage reaction was carried out on dihydro-caffeic acid derivative 1922 using the iron(III)-catalyzed peracetic acid cleavage process of Pandell.25 This produced the cyclized muconic acid derivative 20 which could be transformed into pyrone 21 by treatment with hydrochloric acid. Bromination followed by azide displacement gave key intermediate 22 which could either be reduced directly to (i)-stizolobic acid 16 or ammonolyzed and then reduced to give ( )-3-(6-carboxy-2-oxo-4-pyridyl)alanine 17 (Scheme 4). 

The reagent is prepared just as the corresponding trichloride is prepared by reaction of catechol with PBr, and then bromine. It reacts with formic acid esters to give a,a-dibromomethyl alkyl ethers 1... 

Alternatively, with respect to the missing corresponding brominated catechols the chemical degradation released already brominated phenoxy moieties linked by covalent ether bondings to the geopolymers. 

Octaalkyl-substituted phthalocyanine [152] can be synthesized by bromin-ation of dialkylbenzene accessible via a Grignard reaction. The synthesis of the alkoxy-substituted phthalocyanines [153] starts from catechol. The reaction with alkylhalide is followed by a bromination in positions 4 and 5. Alkoxy-methyl-substituted phthalocyanines [154] are obtained by substitution of o-xylene with bromine and subsequent radical bromination of the two methyl groups of l,2-dibromo-4,5-dimethylbenzene. The alkoxy groups are introduced by reacting the tetrabromo compound with the corresponding alcoholate. 

Bromination of dibutyl vinylboronate at low temperature readily affords a stable di-bromo derivative [2, 3]. Similarly, ( )-alkenylboronic acids or their catechol esters yield the corresponding substituted compound by stereospecific trans addition of bromine. Treatment with base induced anti elimination of the boronic group and the bromine ion. The final result of this sequence was the replacement of boron by bromine with inversion of olefin geometry in excellent yields and 99% stereochemical purities (Scheme 9.1) [4]. 

Methods which are applicable to relatively few phenols, include the bromine method (82) for phenol, the indophenol method (77) for p-amino-phenol, the phloroglucinol method (68) for quinol, and the cobalt method for catechols (2). 

The synthesis of peripherally substituted octa-alkoxyphthalocyanines is straightforward (Scheme 49) [186]. Catechol is alkylated then brominated to give a dialkoxydi-bromobenzene. Reaction with copper cyanide in DMF affords the phthalonitrile, which can be converted to a phthalocyanine under standard cyclization conditions. The lithium alkoxide/alcohol method is usually avoided to prevent any possibility of transetherification. 

Alkynes are reactive toward hydroboration reagents. The most useful procedures involve addition of a disubstituted borane to the acetylene. Catechol borane (l,3>2-benzodioxaborole), which is prepared from equimolar amounts of catechol (1,2-dihydroxybenzene) and borane, is a particularly useful reagent for hydroboration of acetylenes.Protonolysis of the adduct with acetic acid results in reduction of the original alkyne to the corresponding c/5-alkene. Oxidative workup with hydrogen peroxide gives ketones via an enol intermediate. Treatment of the vinyl borane with bromine and base leads to the vinyl bromide. The net anh-addition has been rationalized on the basis of anh-addition of bromine followed by a second z/tr/-elimination of bromide and boron but there are exceptions to this generalization. 

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