Naphthalene formylation

The polymerization of 2-furaldehyde by sodium and sodium naphthalene reported by Kulakov and Kamenskii151 did not produce structure 32, but rather some resinous oligomeric materials formed through the interactions of the furan ring with the formyl group. 

Benzene and naphthalene compounds can be formylated under Vil-smeir conditions. The formyl compounds, with or without isolating, can be condensed with amino arenes to give leuco compounds. In this reaction, the benzhydrol intermediate is not isolated.21,79,84 86 The reaction is generally carried out in an alcohol solvent such as isopropanol, butanol, or pentanol and an acid catalyst such as hydrochloric acid, sulfuric acid, or methanesul-fonic acid.87 Acetic acid can also be used both as catalyst and as the solvent. Urea sometimes is added as catalyst.84,88 Terephthaldehyde reacts with W-diethyl-3-methylaniline89 and substituted azulenes to give a bis-triphenylmethane21 57 and 58, respectively. 

Studies using the 1,8-naphthalene and 4,5-phenanthrene templates have been made (Bowden and Last, 1970, 1973a). The rates of alkaline hydrolysis of the methyl 8-formyl-1-naphthoate [23] and 4-formylphenanthrene-4-carboxylate [24] are very fast and have dramatic enhancements over... 

Photolytic. Based on data for structurally similar compounds, acenaphthylene may undergo photolysis to yield quinones (U.S. EPA, 1985). In a toluene solution, irradiation of acenaphthylene at various temperatures and concentrations all resulted in the formation of dimers. In water, ozonation products included 1,8-naphthalene dialdehyde, 1,8-naphthalene anhydride, 1,2-epoxyacenaphthylene, and 1-naphthoic acid. In methanol, ozonation products included 1,8-naphthalene dialdehyde, 1,8-naphthalene anhydride, methyl 8-formyl-1-naphthoate, and dimethoxyacetal 1,8-naphthalene dialdehyde (Chen et al., 1979). Acenaphthylene reacts with photochemically produced OH radicals and ozone in the atmosphere. The rate constants and corresponding half-life for the vapor-phase reaction of acenaphthylene with OH radicals (500,000/cm ) at 25 °C are 8.44 x lO " cmVmolecule-sec and 5 h, respectively. The rate constants and corresponding half-life for the vapor-phase reaction of acenaphthylene with ozone at 25 °C are... 

Besides 1-15 to 1-17, several other formylation methods are known.302 In one of these, dichloromethyl methyl ether formylates aromatic rings with Friedel-Crafts catalysts.303 ArCHClOMe is probably an intermediate. Orthoformates have also been used.304 In another method, aromatic rings are formylated with formyl fluoride HCOF and BF3.305 Unlike formyl chloride, formyl fluoride is stable enough for this purpose. This reaction was successful for benzene, alkylbenzenes, PhCl, PhBr, and naphthalene. Phenols can be regioselectively formylated in the ortho position in high yields by treatment with two equivalents of paraformaldehyde in aprotic solvents in the presence of SnCL and a tertiary amine.306 Phenols... 

Other Formylations. Formyl fluoride, the only known stable formic acid derivative, can be used to perform Friedel-Crafts-type acylation to form aromatic aldehydes. The method was developed by Olah and Kuhn.105 Although a number of Lewis acids may be used, BF3 is the best catalyst. It is dissolved in the aromatic compound to be formylated then formyl fluoride is introduced at low temperature and the reaction mixture is allowed to warm up to room temperature. The aldehydes of benzene, methylbenzenes, and naphthalene were isolated in 56-78% yields. Selectivities are similar to those in the Gattermann synthesis ( toiuene benzene = 34.6, 53.2% para isomer). The reacting electrophile was suggested to be the activated HCOF BF3 complex and not the free formyl cation. Clearly there is close relationship with the discussed CO—HF—BF3 system. 

It has also been fotind recently that the 3-(/>-tolyl)- and 3-phenyl-6-methyl-1,2-benzisoxazoles (90 and 91) can be utilized in the Anil Synthesis,54 since this ring system was found to be alkali stable. Hence, for example, 90 and 91 give, on reaction with Schiff s base from 1-formyl-naphthalene and p-chloroaniline, the styryl derivatives 92 and 93, respectively. 

A specific feature of these conversions of dimers 276 (R3 = H) is produced by the formyl group. Thus, treatment of 281 with a mixture of aqueous alkaline solution and dioxane at room temperature leads to cyclic semiacetals 284. The precursor compounds towards 284 are the ring-opened intermediates 282, which can be also isolated on treatment of dimer 281 with aqueous sodium acetate [90KGS(ip3)]. Heating of semiacetal 284 (as well as 282 and dimer 281) in concentrated alkaline solutions results in the naphthalene derivative 285, which is obviously formed via ring opening to the hydroxyaldehyde 283, followed by elimination of water. 

Substituted naphthalenes (acenaphthene, 2-methylnaphthalene) are also formylated by N,N-dialkylforinainides, but in low (20, 26%) yields. Generally speaking, several other methods of formylation and acylation exist in the organic synthesis repertoire. Nevertheless, the procedure described here is useful, for it uses inexpensive starting materials. 

Formylation.2 Dimethylformamide and trifluoromethanesulfonic anhydride form an iminium salt (1) that is more reactive than that formed from dimethylformamide and POCl3, which is generally used for formylation (Vilsmeier reagent). Although the Vilsmeier reagent does not react with naphthalene or phenanthrene, reactions with 1 results in 1-naphthalenacarbaldehyde in 50% yield and in 3-phenanthrenecarbaldehyde in 25% yield. 

Pentane-washed NaH (4.1 g) was suspended in 70 ml DMSO and a solution of ethyl (E,E)-6-(diethoxyphosphinyl)-3-methyl-2,4-hexdienolate (24.5 g) dissolved in 70 ml DMSO added. The reaction was stirred for 30 minutes at ambient temperature and 2-formyl-3-hexyl-5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-naphthalene (11.3 g) dissolved in 70 ml DMSO and 35 ml THE added. The mixture was stirred 2 hours and the product precipitated in ice water acidified with 6M HCl. The mixture was extracted with EtOAc and purified by flash chromatography on silica gel with hexane/methyl t-butyl ether, 98 2, and the product isolated as a pale yellow oil. 

Formylation of naphthalene-based heterocyclic systems 03UK498. 

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