Naphthalen-l-one

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>. 

A more recent application of oxime derivatives as prodrugs is the design of cascade prodmgs of dopamine agonists for the treatment of Parkinson s disease. As shown in Scheme 16, enones such as S-(-)-6-(Af,Af-di-n-propylamino)-3,4,5,6,7,8-hexahydro-2//-naphthalen-l-one (103) can be oxidized in vivo to catecholamines... 

The complex thioamide lolrestat (8) is an inhibitor of aldose reductase. This enzyme catalyzes the reduction of glucose to sorbitol. The enzyme is not very active, but in diabetic individuals where blood glucose levels can. spike to quite high levels in tissues where insulin is not required for glucose uptake (nerve, kidney, retina and lens) sorbitol is formed by the action of aldose reductase and contributes to diabetic complications very prominent among which are eye problems (diabetic retinopathy). Tolrestat is intended for oral administration to prevent this. One of its syntheses proceeds by conversion of 6-methoxy-5-(trifluoroniethyl)naphthalene-l-carboxyl-ic acid (6) to its acid chloride followed by carboxamide formation (7) with methyl N-methyl sarcosinate. Reaction of amide 7 with phosphorous pentasulfide produces the methyl ester thioamide which, on treatment with KOH, hydrolyzes to tolrestat (8) 2[. 

Since dihydroarylethenes are more reactive than the corresponding fully aromatic compounds, their use in the cycloaddition reactions is preferred in order to carry out the reactions under mild conditions with higher yields. Some reactions of 3,4-dihydro-1-vinylnaphthalene (103) [33], 3,4-dihydro-2-vinyl-naphthalene (104) [34], and l,2-dihydro-4-vinylphenanthrene (105) [35] with 4-acetoxy-2-cyclopentenone (98) and 2-inden-l-one (106) are summarized in Schemes 5.11-5.13. 

The residue was purified by flash chromatography using petroleum ether-diethyl ether (9 1) as eluent to give (IS, VR)-1.2.3.4-tetrahydro-3,-/.v propyl-spiro [naphthalene-2,2 -oxirane]-l-one as a yellow oil (190 mg, 0.88 mmol, 90%). 

Complex hydrides have been used rather frequently for the conjugate reduction of activated dienes92-95. Just and coworkers92 found that the reduction of a,ft-unsaturated ketene 5,5-acetals with lithium triethylborohydride provided mixtures of 1,4- and 1,6-reduction products which were transformed into enals by treatment with mercuric salts (equation 27). Likewise, tetrahydro-3//-naphthalen-2-ones can be reduced with L-Selectride to the 1,6-reduction products93 -95 this reaction has been utilized in the stereoselective synthesis of several terpenes, e.g. of (/ )-(—)-ligularenolide (equation 28)95. Other methods for the conjugate reduction of acceptor-substituted dienes involve the use of methylcopper/diisobutylaluminum hydride96 and of the Hantzsch ester... 

Bromochloroaniline, see o-Bromoaniline Bromochloromethane, see Dibromochloromethane Bromochloronaphthalene, see Naphthalene l-Bromo-3-chloropropan-2-one, see l,2-Dibromo-3-chloropropane... 

The well-known instability of the disulhde anion-radicals, (R SSR ), is apparently explained by the antibonding electron population, presumably in the framework of the disulfide bond. In some cases, these anion-radicals turned out to be more or less stable (Breitzer et al. 2001). Two examples are shown in Schemes 3.25 and 3.26 that needs to be distinguished. First, one-electron reduction of naphthalene-l,8-disulhde generates the corresponding anion-radical (Scheme 3.25). 

Derivatives of the naphthalen-l,4 -imine ring system (2) have become available only since the discovery of cycloaddition reactions of benzyne, on the one hand, and the recent rapid development of isoindole chemistry on the other. 

With one exception, naphthalen-l,4-imines with a double bond between C-2 and C-3 are not known to dissociate thermally by either possible retro-Diels-Alder pathway (the reverse of reactions described in Section III, A, 1 and 2), and the enthalpy requirements for the formation of a benzyne or an acylic acetylene are doubtless unfavorable. However, the mass spectra of compounds 93-99 reveal one important fragmentation of the molecular ions to be loss of dimethyl acetylene-dicarboxylate, and another fragmentation pathway involves the formation of nitrilium ions MeC=NR and PhC=NR from 93-95 and 96-99, respectively. ... 

Oxidation of several 1,1-bisphenols 78 with IBD gives spirobenzofuran derivatives of general formula 79 (Eq. 21). This approach, when applied to benzylidine l.l -bisnaphthols 80, leads to a stereospecific cyclization, thereby forming the less hindered naphtho[2,l-fi]furan-2(l//)-spiro-r-(2//)-naphthalene-2 -ones (82) [80JCS(P1)1978,80JCS(P1)1986]. The conversion 80 to 82 probably occurs through intermediate 81 (Scheme 25). 

Sumimoto introduced a new sebacic acid process including several catalytic hydrogenation reactions.342 The synthesis starts with naphthalene, which is first partially hydrogenated to tetralin over cobalt oxide or molybdenum oxide, then to decalin over ruthenium or iridium on carbon. The selectivity to cw-decalin is better than 90%. In a later phase of the synthesis 5-cyclododecen-l-one is hydrogenated over Raney nickel to obtain a mixture of cyclododecanone and cyclodode-canol in a combined yield of 90%. The selectivity of this step is not crucial since subsequent oxidation of either compound leads to the endproduct sebacic acid. 

Further bromination of 3,4,6-tribromo-5-hydroxybenzo[6]thio-phene affords the 2,3,4,6-tetrabromo derivative in the absence of acetate ion, and 3,4,4,6-tetrabromo-4,5-dihydrobenzo[6]thiophen-5-one in the presence of acetate ion. 421 On treatment of 3,4-dibromo-, 4,6-dibromo-, 3,4,6-tribromo-, or 2,3,4,6-tetrabromo-5-hydroxybenzo-[6]thiophene with nitric acid in acetic acid, the corresponding unstable orange crystalline 4-bromo-4-nitro-4,5-dihydrobenzo[6]thio-phen-5-one is obtained.152,421 Hence, once both positions ortho to the hydroxyl group in 5-hydroxybenzo[6]thiophene are occupied by bromine, the properties of these compounds are analogous to the properties of l-bromo-2-naphthol which, on bromination in acetic acid in the presence of acetate ion, affords l,l-dibromo-l,2-dihydro-naphthalen-2-one whereas, in its absence, it affords l,6-dibromo-2-naphthol.616 The behavior of l-bromo-2-naphthol and its derivatives on nitration is similar to that of 4,0-dibromo-5-hydroxybenzo[6]thio-phene and its derivatives.162,616... 

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