2 -Hydroxy-4 -methoxyacetophenone

The AFO reaction has seen very few variations since it was first reported in 1934. However, the most significant modification was reported in 1958 by Ozawa and further elaborated by Smith and others. Prior to this modification the intermediate chalcones were purified and then subjected to hydrogen peroxide in a basic medium. With the modification, the chalcone was generated in situ, from an aldehyde and a hydroxyacetophenone, and then allowed to react with aqueous hydrogen peroxide in the presence of sodium hydroxide to deliver the flavonol. Smith and coworkers conducted a limited study to examine the scope and limitations of this modification.Flavonols were delivered in 51-67% however, no flavonols were isolated with highly reactive aldehydes such as p-nitrobenzaldehyde and when 2-hydroxy-4-methoxyacetophenone was used. 

The authors reported the chiral separation of proline and thereonine amino acid up to 20 and 6g, respectively, in a single run. Micropreparative resolution of lecucine was presented. The resolution was discussed with respect to the degree of sorbent saturation with copper(II), elution rate, eluent concentration, temperature, and column loading condition [16]. Weinstein [74] reported the micropreparative separation of alkylated amino acids on a Chiral ProCu column. In another article, a preparative chiral resolution of 3-methylene-7-benzylidene-bicyclo[3.3.1]nonane was achieved on 7.5% silver(I)-d-camphor- 10-sulfonate CSP [75]. Later, Shieh et al. [71] used L-proline-loaded silica gel for the chiral resolution of (ft,5 )-phcnylcthanolaminc as the Schiff base of 2-hydroxy-4-methoxyacetophenone. Gris et al. [76] presented the preparative separations of amino acids on Chirosolve L-proline and Chirosolve L-pipecolic acid CSPs. 

Aromatic amine antioxidants were prepared by condensation of aniline, aralkylated diphenylamine or 2,2,4-trimethyl-l,2-dihydroquinoline with formaldehyde [165]. The latter was also used for the synthesis of other stabilizers a LS was formed via condensation with 2,4-dihydroxybenzophenone [166], a MD 131 with 2-hydroxy 4-methoxyacetophenone [167], another MD was formed with 8-hydroxyquinoline [168] and a BIO-S 132 with 4-aminosalicylic acid [169]. 

Racemic homopterocarpin has been synthesised (ref. 107) from a chalcone obtained by the condensation of 2-hydroxy-4-methoxyacetophenone with 2,4-dibenzyloxybenzaldehyde. Conversion to an isoflavone with thallium (III) nitrate was followed by hydrogenation to generate the racemic furanochroman (C)in low yield together with two other products (A) and (B). Chromatographic separation of (C) and methylation afforded the final product as shown in Scheme 30. 

Preparation by reaction of bromine on 2-hydroxy-4-methoxyacetophenone with titanium tetrachloride in methylene chloride at r.t. (65%) [2519]. 

Preparation by diazotization of 5-amino-2-hydroxy-4-methoxyacetophenone and replacement of the diazonium group by bromine (Sandmeyer reaction) [1836]. Also obtained by reaction of dimethyl sulfate on 5-bromoresacetophenone in sodium hydroxide [1836]. 

Preparation by hydrolysis of 3-acetoxy-2-hydroxy-4-methoxyacetophenone with concentrated hydrochloric acid in refluxing aqueous ethanol (84%) [2813]. 

Also obtained by partial dealkylation of 2-hydroxy-3,4-dimethoxyacetophenone [2406,2814] with hydrobromic acid in acetic add at r.t. (46%) [2814] or by partial dealkylation of 3-ethoxy-2-hydroxy-4-methoxyacetophenone in the same conditions (22%) [2814]. 

Preparation by diazotization of 5-amino-2-hydroxy-4-methoxyacetophenone, followed by decomposition of the diazonium salt obtained [2530]. 

Preparation from 5-ethyl-2-hydroxy-4-methoxyacetophenone by demethylation with boiling pyridinium chloride (40%) [3013]. 

Preparation by reaction of 2-meth-ylbut-3-en-2-ol with 2-hydroxy-4-methoxyacetophenone in the presence of boron trifluoride ether-ate [2326],... 

Obtained by treatment of 3-fluoro-2-hydroxy-4-methoxyacetophenone with methyl iodide in the presence of potassium carbonate in refluxing acetone for... 

Also obtained (by-product) by reaction of bromine on 5-bromo-2-hydroxy-4-methoxyacetophenone in acetic acid [4468]. 

Obtained by reaction of cupric bromide with 2-hydroxy-4-methoxyacetophenone, in refluxing chloroform-ethyl acetate mixture [4391,4413], (quantitative yield) [4391] according to [4390], (62%) [4483] or in refluxing dioxane (44%) [4484], (10%) [4411]. 

Preparation by reaction of bromine with 2-hydroxy-4-methoxyacetophenone in a mixture of ethyl ether and chloroform [4413] according to [4414]. 

P-Orcacetophenone. 2 4 -Dihydroxy-6 -melhylacetophenone, 1572 y-Orcacetophenone. 2 6 -Dihydroxy-4 -methylacelophenone, 1572 Orcinol. 5-Melhyl-l,3-benzenediol, 1241,1324, 1419, 1466, 1481 Oxyayanin-A triethyl ether. 5,2, 5 -Triethoxy-3,7,4 -trimethoxyflavone, 1334 Oxyayanin-B triethyl ether. 5,6,3 -Triethoxy-3,7,4 -trimethoxyflavone, 1341 Oxyayanin-A trimethyl ether. 3,5,7,2 4, 5 -Hexamethoxyflavone, 1330 Paeonol. 2 -Hydroxy-4 -methoxyacetophenone, 1573,1577, 1622 Patuletin hexamethyl ether. 3,5,6,7,3 4 -Hexametfioxyflavone, 1337 Patuletin pentaethyl ether. 3,5,7,3 4 -Pentaethoxy-6-methoxyflavone, 1350 Penduletin dimethyl ether. 3,5,6,7,4 -Pentamethoxyflavone, 1337 O-Pentamethyldihydromelanoxetin. 3,7,8,3, 4 -Pentamethoxyflavanone, 1329... 

The acetylation (with AC2O and HC104) and Vilsmeier formylation of sterically hindered phenols have been investigated. Substituted o-hydroxy-benzophenones have been prepared in 18-68% yields by treatment of the HMPT complexes of bromomagnesium phenoxides with aromatic aldehydes. " Phenolic O- vs. C-benzoylation has been studied, with particular reference to 3,4-disubstituted phenols. Previous work on the use of trifluoroacetic anhydride to promote aromatic acylation has been extended to the preparation of symmetrical and unsymmetrical benzophenones via reaction between the methyl and benzyl ethers of orcinol and the same ethers of phloroglucinolcarboxylic acid. " Other phenolic acylations include some chalcone syntheses and the acetylation and benzoylation of 2-hydroxy-4-methoxyacetophenone (peonol). ... 

Me ether [552-41-0]. 2 -Hydroxy-4 -methoxyacetophenone, Paeonol, Peonol CgHioOj M 166.176... 

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