Naphthalene 1,2-dihydronaphthalene, catalytic

Dihalocarbenes, in two-phase catalytic systems, 35 393-398, 408-414 Dihydronaphthalenes, intermediates of naphthalene hydrogenation, 18 32, 33 Diiodocyclodextrin, 32 437-438 Diisopropyl fluorophosphate, as inhibitor, 20 388... 

Since different reactivity is observed for both the stoichiometric and the catalytic version of the arene-promoted lithiation, different species should be involved in the electron-transfer process from the metal to the organic substrate. It has been well-established that in the case of the stoichiometric version an arene-radical anion [lithium naph-thalenide (LiCioHg) or lithium di-ferf-butylbiphenylide (LiDTBB) for using naphthalene or 4,4 -di-ferf-butylbiphenyl (DTBB) as arenes, respectively] is responsible for the reduction of the substrate, for instance for the transformation of an alkyl halide into an alkyllithium . For the catalytic process, using naphthalene as the arene, an arene-dianion 2 has been proposed which is formed by overreduction of the corresponding radical-anion 1 (Scheme 1). Actually, the dianionic species 2 has been prepared by a completely different approach, namely by double deprotonation of 1,4-dihydronaphthalene, and its X-ray structure determined as its complex with two molecules of N,N,N N tetramethylethylenediamine (TMEDA). ... 

Naphthalene can be reduced more easily than benzene. With sodium in alcohol, 1,4-dihydronaphthalene is formed. Catalytic hydrogenation gives tetralin (1,2,3,4-tetrahydronaphthalene). Further reduction to give perhydro-naphthalene (decalin) can be achieved on prolonged catalytic hydrogenation at relatively high temperatures and pressures ... 

An alternative mode of reactivity is observed for [Os]-naphthalene when the nucleophile for the tandem addition is built into the electrophile. The normal mode of reactivity results in the formation of cis-l,4-dihydronaphthalenes (vide supra), but when a solution of the methyl vinyl ketone Michael addition product 24 in methanol (Table 6, entry 1) and a catalytic amount of triflic acid are allowed to react, the complexed hydrophenanthrenone 25 is isolated in 89 % yield [18]. This reactivity results from the pendant ketone undergoing a tauto-merization to form an enol, which can then attack the allyl cation at C2. The stereochemistry of the nucleophilic addition is still anti to the face involved in the metal coordination, but the... 

It is interesting to note that catalytic reactions tending to equilibrate tetralin, 1,2-dihydronaphthalene and naphthalene (19,39) will serve to generate free radicals since 1,2-dihydronaphthalene rapidly undergoes molecular disproportionation with tetralin. For instance, at equilibrium a 0.5% solution of naphthalene in tetralin (typical of distilled tetralin) will generate ca. 10 2 mol percent 1,2-dihydronaphthalene at 400°C, which will, in turn, form ca. 10 7 M tetralyl radicals (see above). 

Naphthalene oxides. The Diels-Alder reaction of 1,4-diacetoxybutadiene (1) with benzyne (generated from o-benzenediazonium carboxylate, 1, 46) gives the diacetate of l,4-dihydronaphthalene-cis-l,4-diol (2) in 53% yield. The product is converted into 3 by reaction with hydrogen peroxide and catalytic amounts of osmium tetroxide. The monotosylate of 3 is converted into 4 by treatment with base. This epoxy diol has the stereochemistry found in the carcinogenic epoxy diols formed as metabolites of aromatic hydrocarbons. The dimesylate of 3 is converted into the syft-diepoxide 5. 

Naphthalene is reduced to 1,4-dihydronaphthalene by sodium and alcohol. Isomerization of this product to 3,4-dihydronaphthalene occurs with sodamide in liquid ammonia. Tetrahydronaphthalene (tetralin) is formed from naphthalene by sodium in amyl alcohol or by reduction with nickel-aluminum alloy and aqueous alkali. Catalytic hydrogenation of naphthalene can be stopped at the tetralin stage over copper chromite, Raney nickel, or alkali metal catalysts. cis-Decahydronaphthalene is produced by high-pressure hydrogenation of tetralin over Adams catalyst, whereas a mixture of cis- and trans-decalins is obtained from naphthalene under the same conditions. ... 

Aromatic Rings. - The ability of electrolytic reduction of naphthalene to produce dihydronaphthalene offers an advantage over the catalytic process, which can only be halted at the tetralin stage. It is believed that Hoechst are carrying out pilot plant studies with a view to producing 1,4-dihydro-naphthalene and 1,4-dihydronaphthalic esters commercially by electrolytic reduction of naphthalene and naphthyl esters. 

As in the case of carbonylation, the reaction of alkynes with nickel metallacycles is often followed by reductive elimination. In some cases, the insertion product is stable and can be isolated (e.g., alkyne insertion in nickelalac-tones or fluorinated metallacycles, Equation (99)), but more frequently it is unstable and decomposes rapidly to afford substituted benzenes, dihydronaphthalenes,naphthalenes, or phenanthrenes. " The reaction of Ni(0) dippe complexes with biphenylene and alkynes in the presence of traces of O2 catalytically produces phenanthrenes, in a process that involves the intermediacy of a carbonickelacycle. " ... 

Fused Systems.—Naphthalene and Derivatives. A new method of aromatization of partially hydrogenated aromatic hydrocarbons overcomes the difficulty of the competing Diels-Alder reaction of reactive arenes. The method is based on deprotonation-hydride elimination in which potassium fencholate (277) serves as the base and fenchone (278) as the hydride acceptor, catalytic amounts only of fencholate being required since it is regenerated in the aromatisation step. In this way, the conversion of 1,2-dihydronaphthalene into naphthalene and of 9,10-dihydroanthracene into anthracene proceeds almost quantitatively. 

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