- Preparation and uses of N-methylnitrone
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Oxidation of secondary amines with hydrogen peroxide and sodium tungstate is reported to give good yields of nitrones. However, when using dimethylamine in this manner, a considerable amount of N,N-dimethylformamide was produced as a co-product. To more selectively produce N-methylnitrone from dimethylamine, a two-step process is used which comprises (a) mixing together dimethylamine and a peroxidic compound, and subjecting the resultant mixture to reaction conditions effective to form a reaction mixture in which N,N-dimethylhydroxylamine has been formed; and (b) mixing together (i) reaction mixture from (a), (ii) a peroxidic compound, and (iii) a transition metal-containing oxidation catalyst, and subjecting the resultant mixture to reaction conditions effective to form a reaction mixture in which N-methylnitrone has been formed. Highest yields of N-methylnitrone are achieved by conducting step (b) at a pH in the range of 7 to about 12, and at a temperature in the range of about -10° to about 100° C.
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- Preparation and uses of hydrocarbylnitrones
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Nitrones are produced by reaction of primary amine with aldehyde or ketone, in the presence of a transition metal-containing oxidation catalyst, and a peroxidic compound. The nitrone can then be reacted with a vinylaromatic compound to produce a 2-hydrocarbyl-5-arylisoxazolidine. Both such reactions can be conducted concurrently by including the vinylaromatic compound in the initial reaction mixture. Hydrogenation of the 2-hydrocarbyl-5-arylisoxazolidine, e.g., using hydrogen and a palladium-carbon catalyst, forms an N-hydrocarbyl-3-aryl-3-hydroxypropylamine. Such reactions enable, inter alia, synthesis of the racemic hydrochloride salt of N-methyl-3-phenyl-3-[4-trifluoromethyl)phenoxy]-propylamine, known generically as fluoxetine hydrochloride, a widely used antidepressant.
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