Naphthalenes, 1,7-dimethoxy

Naphthalenes, 1,7-dimethoxy-, metalation 16, 839 Naphthalenes, 1,4,5,6,7,8-hexahydro-2-methoxy-... 

The Harris technique used alkaryl ethers instead of halides as illustrated in Figure 23.28 by reaction of a,a -dimethoxy-p-xylene and naphthalene. 

Let us discuss now the conditions required for the electron transfer process. This reaction requires, of course, a suitable electron donor (a species characterized by a low ionization potential) and a proper electron acceptor, e.g., a monomer characterized by a high electron affinity. Furthermore, the nature of the solvent is often critical for such a reaction. The solvation energy of ions contributes substantially to the heat of reaction, hence the reaction might occur in a strong solvating solvent, but its course may be reversed in a poorly solvating medium. A good example of this behavior is provided by the reaction Na -f- naphthalene -> Na+ + naphthalene". This reaction proceeds rapidly in tetrahydrofuran or in dimethoxy... 

Compound 1 is completely hydrogenated to the saturated ketone, 4-(6-methoxy-2-naphthyl)-3-butan-2-one. Compound 2 is hydrogenated in high ytield (90%) to the saturated ketone, 2-acetyl-5,8-dimethoxy-tetrahydro-naphthalene, which can be obtained in the pure form by fractional crystallization from chloroform. 

In view of our results obtained in reactions of the tetrahalogeno-benzynes with aromatic compounds we carried out a reaction of tetra-fluorobenzyne with the A-ring aromatic steroid 3,l7,fl-dimethoxy-oestra-l(10),2,4-triene (119) 154>. As we expected the initially formed enol-ethers were very rapidly hydrolysed and the adducts were isolated as the ketones (120) and (121). The mass spectra of the compounds (120) and (121) did not show molecular ion peaks and as anticipated the ketones were rapidly converted into the naphthalenes (122) and (123) photo-chemically. 

Kwakman et al. [65] described the synthesis of a new dansyl derivative for carboxylic acids. The label, N- (bromoacetyl)-A -[5-(dimethylamino)naphthalene-l-sulfonyl]-piperazine, reacted with both aliphatic and aromatic carboxylic acids in less than 30 min. Excess reagent was converted to a relatively polar compound and subsequently separated from the derivatives on a silica cartridge. A separation of carboxylic acid enantiomers was performed after labeling with either of three chiral labels and the applicability of the method was demonstrated by determinations of racemic ibuprofen in rat plasma and human urine [66], Other examples of labels used to derivatize carboxylic acids are 3-aminoperylene [67], various coumarin compounds [68], 9-anthracenemethanol [69], 6,7-dimethoxy-l-methyl-2(lH)-quinoxalinone-3-propionylcarboxylic acid hydrazide (quinoxalinone) [70], and a quinolizinocoumarin derivative termed Lumarin 4 [71],... 

In an Erlenmeyer flask capped with a rubber septum a mixture of naphthalene, 1,2-dimethoxy-ethane and enough sodium to yield an 0.5-1.0 m solution of anion radical is stirred with a glass-covered stirring bar for 1-1.5 hours, by which time the anion radical will have formed and scavenged the oxygen inside the flask. A solution of one-sixth to one-third of an equivalent of the sulfonamide in dimethoxyethane is injected by syringe and the mixture is stirred at room temperature for approximately 1 hour. Quenching with water produces amines in 68-94% isolated yields. 

In the same way, the displacement of the unpaired electron over the whole molecules was observed for (d) and (e) cation radicals from Scheme 1-13, in which 1,4-dimethoxy-naphthalene units are syn- or anti-annelated to [2.2]paracyclophane. Taken together, the experimental results considered provide direct evidence for the through-bond mechanism of electron transfer in these paracyclophane systems. In a recent study, the electron transfer between 1,4-dimethoxybenzene and 7,7-dicyanobenzoquinone methide moieties in syn-or anh -cyclophane systems reached the same conclusion The through-bond mechanism... 

Another application of 2-lithiated benzo[ ]furan to generate a structurally interesting benzo[ ]furan derivative was realized by reaction of 2-lithiated benzo[ ]furan with 4,4-dimethoxy-4//-naphthalen-l-one, followed by hydrolysis, as shown in Equation (72) <2003JME532>. 

In the presence of mineral acids, the hydroxyl groups in 44 can be replaced by alkoxy or alkylperoxy groups to give 45, 46, or 47. The monomethoxy compound (48) occurs as an intermediate in the formation of the dimethoxy compound (45). 48 was obtained by Bailey et al.i6 on ozonization of naphthalene, 2-methoxynaphthalene, and 2-ethoxynaphthalene in methanol. Ozonization of 2-ethoxynaph-thalene in ethanol leads to the diethoxy compound (46).46 The peroxides 44-46 and 48 can be converted into o-phthaldialdehyde (in 55% yield from 48) by hydrogenation in the presence of a Lindlar catalyst.45 The peroxide oxygen in 45-48 cannot be quantitatively determined by iodometry.45... 

The initiation step is normally fast in polar solvents and an initiator-free living polymer of low molecular weight can be produced for study of the propagation reaction. The propagation step may proceed at both ends of the polymer chain (initiation by alkali metals, sodium naphthalene, or sodium biphenyl) or at a single chain end (initiation by lithium alkyls or cumyl salts of the alkali metals). The concentration of active centres is either twice the number of polymer chains present or equal to their number respectively. In either case the rates are normalized to the concentration of bound alkali metal present, described variously as concentration of active centres, living ends or sometimes polystyryllithium, potassium, etc. Much of the elucidation of reaction mechanism has occurred with styrene as monomer which will now be used to illustrate the principles involved. The solvents commonly used are dioxane (D = 2.25), oxepane (D = 5.06), tetrahydropyran D = 5.61), 2-methyl-tetrahydrofuran (D = 6.24), tetrahydrofuran (D = 7.39) or dimethoxy-ethane D = 7.20) where D denotes the dielectric constant at 25°C. 

When Nu is electron donating the product is as a rule more easily oxidized than the starting material, resulting in further oxidation under the reaction conditions and, frequently, complex reaction mixtures. The anodic methoxylation of naphthalene, which results in 1-methoxy-, 1,2-dimethoxy-, and 1,4-dimethoxynaphthalene, approximately in a 1 2 1 ratio, serves as an illustration of this problem [67]. However, in other cases, a single major product is obtained after a sequence of reactions, such as the oxidation of mesitylene in MeCN-diluted H2SO4 to 2,4,6-trimethyl-4-hydroxycyclohexa-2,5-dien-l-one in a substitution-elimination reaction [68] or the oxidation of anthracene in MeOH to 9,9,10,l0-tetramethoxy-9,10-dihydroanthracene in a substitution-addition reaction [Eq. (28)] [69]. 

---