2-bromoacetyl-6-methoxynaphthalene

SELECTIVE a-BROMINATION OF AN ARALKYL KETONE WITH PHENYLTRIMETHYLAMMONIUM TRIBROMIDE 2-BROMOACETYL-6-METHOXYNAPHTHALENE AND 2,2-DIBROMOACETYL-6-METHOXYNAPHTHALENE... 

C. 2-Bromoacetyl-6-methoxynaphthalene. To a solution of 1 g. (0.005 mole) of 2-acetyl-6-methoxynaphthalene2 in 10 ml. of anhydrous tetrahydrofuran3 (Note 7) contained in a 125-ml. Erlenmeyer flask is added 1.88 g. (0.005 mole) of PTT in small portions. About 10 minutes is required for this operation. A white precipitate forms immediately and the solution becomes pale yellow. After 20 minutes, 50 ml. of cold water is added, and the crystalline precipitate (Note 8) is filtered and washed with 10 ml. of water. The crude, white 2-bromoacetyl-6-methoxy-naphthalene (ca. 1.3 g., m.p. 100-105°) is recrystallized from 32 ml. of cyclohexane to give 1.1 g. (79%) of crystalline product, m.p. 107-109° (lit. 107-1080)4 (Notes 9 and 10). 

Internal standard 6-methoxynaphthacyl ester of nonanoic acid (Dissolve 2 mmole nona-noic acid and 1 mmole 2-bromoacetyl-6-methoxynaphthalene in 10 mL anhydrous MeCN, add 500 pL triethylamine, heat to 60° for 30 min, cool, add 30 mL water, extract three times with 10 mL portions of diethyl ether. Combine the organic layers and wash them with 5% sodium bicarbonate solution, wash three times with 10 mL portions of water, dry over anhydrous sodium sulfate, evaporate to dryness under reduced pressure, recrystallize from water to give 6-methoxynaphthacyl ester of nonanoic acid (mp 66-8°).) (10)... 

Gatti, R. Cavrini, V. Roveri, R 2-Bromoacetyl-6-methoxynaphthalene A useful fluorescent labelling reagent for HPLC analysis of carboxylic acids. Chromatographia, 1992, 33, 13—18... 

Sample preparation Mix 200 lL of a solution in MeOHnvater 10 90 with 150 (jiL 20 mM 0.5 mM tetrakis(decyl)anunonium bromide in 5 mM pH 7.0 phosphate buffer and 100 xL 4.2 mg/mT. 2-bromoacetyl-6-methoxynaphthalene in acetone, stir at 70° for 65 min, add 150 xL 80 yig/voL, IS in MeCN, sonicate for 1 min, inject a 50 aL aUquot. (Preparation of 2-bromoacetyl-6-methoxynaphthalene is given in Organic Syntheses, Collective Volume 6, page 175 available free of cost at www.orgsyn.org.)... 

Sample is dissolved in MeOH, centrifuged and filtered if necessary, and further diluted with H2O. An aliquot is derivatized with 2-bromoacetyl-6-methoxynaphthalene... 

Phenyltrimethylammonium perbromide reacts like pyridinium perbromide but is easier to prepare and more stable. It dissolves easily in tetrahydrofuran, in which these reactions are performed. It monobromi-nates selectively ketones and cyclic ketals in a-posi-tion without affecting double bonds and reactive benzene rings.—E 2-Acetyl-6-methoxynaphthalene- 2-(co-bromoacetyl)-6-methoxynaphthalene. Y 80%. 

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