4- Amino-2-hydroxyacetophenone

Preparation by diazotization of 4-amino-2-hydroxyacetophenone and replacement of the diazonium group by iodine (Sandmeyer reaction) (46%) [1956],... 

Preparation by reaction of dimethyl sulfate with 4-amino-2-hydroxyacetophenone in the presence of sodium carbonate in boiling water for 40 min (49%) [3156]. 

A solution of 4-amino-2-hydroxyacetophenone and propionaldehyde in methanol was stored over 3 A molecular sieves for 3 days. The solution of 2-hydroxy-4-propyl-iminoacetophe-none so obtained was then treated with hydrogen in the presence of 10% Pd/C (50%) [2464],... 

Other non-traditional preparations of 1,2,3-triazoles have been reported. The rearrangement in dioxane/water of (Z)-arylhydrazones of 5-amino-3-benzoyl-l,2,4-oxadiazole into (2-aryl-5-phenyl-27/-l,2,3-triazol-4-yl)ureas was investigated mechanistically in terms of substituents on different pathways <06JOC5616>. A general and efficient method for the preparation of 2,4-diary 1-1,2,3-triazoles 140 from a-hydroxyacetophenones 139 and arylhydrazines is reported <06SC2461>. 5-Alkylamino-] //-], 2,3-triazoles were obtained by base-mediated cleavage of cycloadducts of azides to cyclic ketene acetals <06S1943>. Oxidation of N-... 

Aminofiavones are also available from chalcones derived from 5-acetamino-2-hydroxyacetophenone (57JOC304). Oxidation by selenium dioxide leads to 6-acetaminoflavones which may be deacetylated to the 6-amino compound, whilst alkaline hydrogen peroxide affords the corresponding flavonols (461) in a typical Algar-Flynn-Oyamada reaction (64CB610). 

Triazolopyrimidines fused with the benzopyrane ring 419 (usually as mixtures of diastereomers) can be obtained by cyclization of 5-(2-hydroxyaryl)-substituted dihydroazolopyrimidines 417, with aldehydes 418, or by direct condensation of 3-amino-1,2,4-triazole 147 with ort/zo-hydroxyacetophenone 421 and 2 mole of the corresponding aldehyde [409, 410] (Scheme 3.133). In the latter case, the... 

Trost and coworkers recently reported that these dinuclear zinc complexes catalyze Mannich reactions with unmodified aromatic hydroxy ketones as donors with excellent enantioselectivity [18]. Mannich-type reactions between an N-para-meth-oxyphenyl (PMP)-protected a-ethyl glyoxalate and hydroxyacetophenone in the presence of a catalytic amount of catalyst 5a afford the desired N-PMP protected amino acid derivative in 76 % yield with a dr of 7 1 and 95 % ee (Eq.5). 

Aminocyclohexenones, easily accessible from 3-acetyl-2,6-dimethylpyrone and secondary amines, are converted in good yield to 2-amino-6-hydroxyacetophenone derivatives278 (equation 229). 

In the same year paper chromatography was first attempted by Benassi (B4) for the simultaneous analysis of 8 tryptophan metabolites (kyn-urenine, 3-hydroxykynurenine, kynurenic acid, xanthurenic acid, anthra-nilic acid, 3-hydroxyanthranilic acid, 2-aminoacetophenone, and 2-amino-3-hydroxyacetophenone), separated by means of a mixtiue of methanol, n-butanol, benzene, and water and revealed through the fluorescence in ultraviolet light of 3655 A. Each compound elicits a different fluorescent color (cf. Table 1). 

The excretion of N-a-acetylkynurenine and kynurenic, xanthurenic, and o-aminohippuric acids was, in all the cases investigated, within the normal range, while 2-amino-3-hydroxyacetophenone and xanthurenic acid 8-methyl ether were always absent. 

Trost and coworkers developed a chiral zinc phenoxide for the asymmetric aldol reaction of acetophenone or hydroxyacetophenone with aldehydes (equations 62 and 63) . This method does not involve the prior activation of the carbonyls to silyl enol ethers as in the Mukaiyama aldol reactions. Shibasaki and coworkers employed titanium phenoxide derived from a phenoxy sugar for the asymmetric cyanosilylation of ketones (equation 64). 2-Hydroxy-2 -amino-l,l -binaphthyl was employed in the asymmetric carbonyl addition of diethylzinc , and a 2 -mercapto derivative in the asymmetric reduction of ketones and carbonyl allylation using allyltin ° . ... 

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