82663-57-8

Upstream product

• 186581-53-3 diazomethane 
• 571-60-8 1,4-Dihydroxynaphthalene 
• 1191-99-7 2,3-dihydro-2H-furan 
• 84-85-5 4-methoxynaphth-1-ol 

Relevant academic research and scientific papers

Oxidation of 4-methoxy-1-naphthol on promoted platinum catalysts

Oxidative coupling of naphthols is a useful method for the formation of new carbon-carbon bonds in organic synthesis. In the presence of hydrogen peroxide, platinum supported on activated carbon catalyses this reaction. The outcome is influenced by the solvent, the reaction temperature and the physical structure of the catalyst. The catalyst structure is determined by the synthesis method and the modifier used (Bi or Sb). Within 40 min 4-methoxy-1-naphthol can be converted to 4,4'-dimethoxy-2,2'-binaphthalenyl-1,1'-diol with a yield of up to 94%, or to 4,4'-dimethoxy-2,2'-binaphthalenylidene-1,1'-dione with a yield of 92%. High amounts of quinoid byproducts (≤22%) are observed in nitromethane as the solvent.

Solvent and Temperature Effects on the Platinum-Catalyzed Oxidative Coupling of 1-Naphthols

Using H2O2 as the oxidant, 1-naphthols with electron-donating groups at the 2- and 4-positions couple oxidatively over a carbon-supported platinum catalyst to 3,3′-substituted 1,1′-binaphthalenylidene-4,4′-diones and 4,4′-substituted 2,2′-binaphthalenylidene-1,1′-diones, respectively. The binaphthalenyl diols are the intermediates. The selectivity to individual products is influenced by the reaction temperature (room temp. or reflux) and by the solvent used. Under reflux, complete conversions are obtained within 40 min. At room temp. high diol yields can be obtained, e.g. 96 % from 2-methyl-1-naphthol in MeOH. Under reflux the reaction proceeds always further to the diones (at least to some extent), and THF is a promising solvent for the selective one-pot two-step oxidation of 1-naphthols to the diones (e.g. 81 % from 4-methoxy-1-naphthol). In most other solvents (reflux) naphthoquinones are observed as byproducts. In an attempt to optimize the yield of menadione, 30.5 % was obtained in boiling MeNO2.

Anodic oxidation of 4-methoxy-1-naphthol

Anodic oxidation of 4-methoxy-1-naphthol 1 in the presence of nucleophiles provided the corresponding products 8-12 and the dimers 13 and 17 were also produced. The reaction mechanism of the oxidation reaction including the [3+2] cycloaddition was investigated.

Reactivity of naphthol towards nucleophiles in anodic oxidation

Reactivity of the anodic oxidation of 4-methoxy-1-naphthol 1 in the presence of nucleophiles has been investigated. The reaction with electron-rich alkenic nucleophiles such as 1-methoxy-4-propenylbenzene 2 and isosafrole 3 gave a very high yield, whereas the reaction with dihydropyran 4 and dihydrofuran 5 gave a moderate yield, but with ethyl vinyl ether 6 gave a very low yield of the substituted dihydronaphthofuran derivatives 7-10 and 12, respectively. Unexpectedly, the glycosyl derivative 11 was preferentially produced rather than naphthofuran 10 upon using 5 as a nucleophile. In addition, the dimers 15 and 16 were obtained in moderate yield without addition of nucleophile to 1. The mechanism of the oxidation reactions including the [3+2] and [5+2] cycloaddition were discussed.

Dimeric Naphthoquinones, XI. - Oxidation Products of Substituted Binaphthyls

1',4,4'-Trimethoxy-2,2'-binaphthyl-1-ol (7a) is oxidized in high yield forming the quinone 8a or the cyclic acetal 22.Under acidic conditions, both compounds are easily transferred into substituted dinaphthofurans.