2-methoxynaphthalen

Methoxynaphthalene [93-04-9] M 158.2, m 73.0-73.6°, b 273°/760mm. Fractionally distd under vacuum. Crystd from absolute EtOH, aqueous EtOH, benzene or n-heptane, and dried under vacuum in an Abderhalden pistol or distd in vacuo. [Kikuchi et al. J Phys Chem 91 574 1987.]... 

The question of the occurrence of cine or aryne substitution in some of these reactions has been raised but not answered adequately. The normal product, 2-methoxynaphthalene was shown to be formed from 2-chloronaphthalene and methoxide ion, and the normal 6- and 8-piperidinoquinolines were proved to be products of piperidino-debromination of 6- and 8-bromoquinolines, all in unspecified yield. More highly activated compounds were then assumed not to react via the aryne mechanism. Even if the major product had been characterized, the occurrence of a substantial or predominant amount of aryne reaction may escape notice when strong orientation or steric effects lead to formation of the normal displacement product from the aryne. A substantial amoimt of concurrent aryne reaction may also escape detection if it yields an amount of cine-substituted material easily removed in purification or if the entire reaction mixture is not chromatographed Kauffman and Boettcher have demonstrated that activated compounds such as 4-chloropyridine do indeed react partially via the aryne mechanism (Section I,C,1). 

In a similar scheme, acylation of 2-methoxynaphthalene gives ketone, 15. This is then converted to the acetic acid by the Wilgerodt reaction. Esterification, alkylation of the carbanion (sodium hydride methyl iodide), and finally saponification affords naproxen (17). The intense current effort on nonsteroid antiinflammatory agents and acrylacetic acids in particular make... 

A number of examples of the use of molten pyridinium chloride (mp 144 °C) in chemical synthesis are known, dating back to the 1940 s. Pyridinium chloride can act both as an acid and as a nucleophilic source of chloride. These properties are exploited in the deallcylation reactions of aromatic ethers [4]. An example involving the reaction of 2-methoxynaphthalene is given in Scheme 5.1-2 [16, 18], and a mechanistic explanation in Scheme 5.1-3 [18]. 

Scheme 5.1-2 The demethylation of 2-methoxynaphthalene to 2-naphthol with pyridinium chloride.

Identical kinetics are exhibited in the analogous oxidations of 1- and 2-methoxynaphthalene to 4-methoxyl-l-naphthyl acetate and 2-methoxy-1,4-naphthoquinone respectively . In these cases the radical-cations may react with acetate ion thus... 

Another patent apphcation (28) describes the use of zeolite/TUD-1 with optionally a metal function for a variety of reactions. In an example, as-synthesized MCM-22 / TUD-1 was tested for acylation of 2-methoxynaphthalene with acetic anhydride to 2-acetyl-6-methoxynaphthalene at 240°C. After reaction for six hours, conversion of 2-methoxynaphthalene reached 56% with 100% selectivity to 2-acetyl-6-methoxynaphthalene. Other zeolite catalysts were similarly tested, but none were nearly as effective. 

In addition to mesitylene, 2-methoxynaphthalene, 1,3,5-trimethoxybenzene, xylene, and anisole have also been benzotriazolylalkylated in this way (the latter two in lower yield). 

Friedel-Crafts acylation is widely used for the production of aromatic ketones applied as intermediates in both fine chemicals and pharmaceutical industries. The reaction is carried out by using conventional homogenous catalysts, which represents significant technical and environmental problems. The present work reports the results obtained in the Friedel-Crafts acylation of aromatic substrates (anisole and 2-methoxynaphthalene) catalyzed by Beta zeolite obtained by crystallization of silanized seeds. This material exhibits hierarchical porosity and enhanced textural properties. For the anisole acylation, the catalytic activity over the conventional Beta zeolite is slightly higher than with the modified Beta material, probably due to the relatively small size of this substrate and the weaker acidity of the last sample. However, the opposite occurred in the acylation of a bulky substrate (2-methoxynaphthalene), with the modified Beta showing a higher conversion. This result is interpreted due to the presence of a hierarchical porosity in this material, which favors the accessibility to the active sites. 

In contrast, the opposite result was observed when these materials were used in the acylation of a bulky substrate (2-methoxynaphthalene, 2-MN). In this case, l-acetyl-2-metoxynaphthalene (1-A,2-MN) and 6-acetyl-2-metoxynaphthalene (6-A,2-MN) are the main reaction products (Scheme 2). The latter is an intermediate for the preparation of Naproxen (antiinflammatory drug) and, therefore, the most interesting product. Initially, 2-MN acylation leads to 1-A,2-MN (the kinetically controlled product). However, at long times, the selectivity to 6-A,2-MN usually increases due to two secondary reactions transacylation of 1-A,2-MN with a molecule of 2-MN and protodeacylation of 1-A,2-MN yielding 2-MN [7],... 

The Beta material prepared by seed silanization show interesting catalytic properties in aromatic acylation reaction, especially when using a bulky substrate, such as 2-methoxynaphthalene. The superior activity and selectivity exhibited by this sample has been related to the presence of a hierarchical porosity, which decreases the steric and diffusional hindrances, favoring the accessibility to the active sites and allowing the occurrence of the transacylation reaction. 

Partial reduction of polyarenes has been reported. Use of boron trifluoride hydrate (BF3 OH2) as the acid in conjunction with triethylsilane causes the reduction of certain activated aromatic systems 217,262 Thus, treatment of anthracene with a 4-6 molar excess of BE3 OH2 and a 30% molar excess of triethylsilane gives 9,10-dihydroanthracene in 89% yield after 1 hour at room temperature (Eq. 120). Naphthacene gives the analogously reduced product in 88% yield under the same conditions. These conditions also result in the formation of tetralin from 1-hydroxynaphthalene (52%, 4 hours), 2-hydroxy naphthalene (37%, 7 hours), 1-methoxynaphthalene (37%, 10 hours), 2-methoxynaphthalene (26%, 10 hours), and 1-naphthalenethiol (13%, 6 hours). Naphthalene, phenanthrene, 1-methylnaphthalene, 2-naphthalenethiol, phenol, anisole, toluene, and benzene all resist reduction under these conditions.217 Use of deuterated triethylsilane to reduce 1-methoxynaphthalene gives tetralin-l,l,3-yielding information on the mechanism of these reductions.262 2-Mercaptonaphthalenes are reduced to 2,3,4,5-tetrahydronaphthalenes in poor to modest yields.217 263... 

FOOD CONSUMPTION, DAILY FOR 5 DAYS (mg/kg body weight) Deer mice, Peromyscus maniculatus 2-Methoxynaphthalene ... 

Acetylation, selective, of 2-methoxynaphthalene, 53, 7 p-ACETYL-a-BROMOHYDROCINNAMIC ACID, 51, 1... 

A 2-1. three-necked flask equipped with a condenser and containing 27 g. (1.1 mole) of magnesium is flame-dried and the atmosphere replaced with nitrogen. A 200-ml. portion of tetra-hydrofuran (Note 1) is added along with several lumps, totaling about 95 g., of 6-bromo-2-methoxynaphthalene (Note 2) and a small crystal of iodine. The mixture is heated to reflux until the boiling becomes spontaneous. An additional 600 ml. of tetra-hydrofuran is added with more of the bromide to maintain a vigorous reflux, until 237.4 g. (1 mole) of 6-bromo-2-mothoxy-... 

Water added at this point hydrolyzes the arylboronic ester extremely rapidly to 2-methoxynaphthalene. 

---