4-Methoxyphenol reaction with

Diels-Alder reactions with furans constitute a major class of cycloaddition reactions, which have been used for the preparation of a variety of new compounds. Some examples will be given in this section. A one-pot stereoselective synthesis of tricyclic -y-lactones was achieved via Diels-Alder reactions of 2-methoxyfuran with masked o-benzoquinones, which are in turn available from the corresponding 2-methoxyphenols <99CC713>. 

A series of azophenol acerands 4 was prepared by condensation of crowned benzoquinones 10 with 2,4-dinitrophenylhydrazine in ethanol [7b], The quinone was derived from p-methoxyphenol (6) as shown in Scheme 1 [8]. By bis(hy-droxymethylation) (67% yield of 6, followed by methylation (92%) of the phenol group and Williamson-type reaction with ditosylates of oligoethyleneglycol in the presence of sodium hydride, crowned 1,4-dimethoxybenzene 9 was obtained in reasonable yields. Oxidative demethylation of 9 with ceric ammonium nitrate (CAN) in aqueous acetonitrile at 50 °C gave the desired crowned benzoquinones 10 in good yields. 

A general route to phenoxathiins 85 (Z = O, Z = S) utilizes the reaction of diphenyl ethers with sulfur. One route to thianthrene 85 (Z, Z = S) involves reaction of sulfur monochloride with benzene over aluminum chloride. Likewise, tf-methoxyphenol reacts with sulfur dichloride to give, depending on the rate of addition of the reactant, 2,8-dihydroxy-3,7-dimethoxythianthrene 89 or l,6-dichloro-2,7-dihydroxy-3,8-dimethoxythianthrene 90 <1997JCM272>. 

Compound 3 was obtained in toluene, THF, and CHCI3 from reaction of SiCU and 8-hydroxyquinoline in the stoichiometric ratio of 1 2. In contrast, the analogous reaction with SiBr4 (in toluene) yields the tris-chelate complex 4. Consequently, the spectrum of the products is predominantly influenced by the reactivity of the silicon source, but a significant dependence on the used solvents was not observed. However, this conclusion is contrary to the results for ligand L H (reactions with 2-[(iV-benzylimino)phenylmethyl]-5-methoxyphenol) mentioned above. Compounds 3 and 4 were isolated, but we do not know exactly the configuration of the silicon-ligand sphere. We were not able to isolate the dibromo complex 5 from the mixture with 4. 

Similar radiolytic yields of phenoxyl radicals have been fonnd in CH2CI2 solntions. The radiolysis of this solvent appeared to be simpler than that of CCLj and permitted determination of rate constants for reactions of Cl atoms. Both phenol and p-methoxyphenol react with diffusion-controlled rate constants (2.5 x 10 ° and 5 x... 

Similarly, anodic oxidation of p-methoxyphenol (140a) was carried out in the presence of the substituted propenylbenzene 143 using teflon-coated electrode to afford the corresponding dihydrobenzofuran 144 in 80% yield (Scheme 27). The hydrophobic coating on the electrode protected the highly reactive intermediate from the solvent and enhanced the reaction with 143. 

Generally, on PhI(OAc)2-promoted oxidation of o-methoxyphenols in MeOH containing a large excess of electron-rich dienophiles, the resulting o-quinone monoketals may undergo an intermolecular Diels-Alder reaction with the dienophiles to afford the corresponding dimers. 4-Methoxycarbonyl-2-methoxyphenol (421) was submitted to PhI(OAc)2-promoted oxidation in MeOH containing benzyl vinyl ether (BVE) or dihydrofuran (DHF)... 

Oxidation of 4-methoxycarbonyl-2-methoxyphenol (421) with PhI(OAc)2 in MeOH was carried out in the presence of cyclopentadiene (CPD) to afford in 87% yield a Diels-Alder adduct 434, which was subjected to photochemical reaction followed by Ac20-BF3-Et20 treatment to give a linear triquinane 435 (47.6% in 2 steps). ... 

ETHYLENE GLYCOL MONOACETATE (542-59-6) C4H8O3 Combustible liquid (flash point 215 °F/102°C oc Fire Rating 1). Unless inhibited p-methoxyphenol is recommended), polymerization can occur, especially when heated. Violent reaction with strong... 

GLYCOL MONOACETATE or GLYCOL-MONOACETIN (542-59-6) C HjOj Combustible liquid (flash point 215°F/102°C oc Fire Rating 1). Unless inhibited (p-methoxyphenol is recommended), polymerization can occur, especially when heated. Violent reaction with strong oxidizers. Incompatible with permanganates, ammonium persulfate, bromine dioxide, strong acids sulfuric acid, nitric acid. On small fires, use dry chemical powder (such as Purple-K-Powder), Halon , or COj extinguishers. 

Corresponding to the reaction with carbon nucleophiles, [11a,h] was reacted wifli different oxygen nucleophiles such as phenols, carbohydrates, steroids, and a-toco-pherol. In addition to 3-methoxyphenol, 2,4-dichlorophenol and 8-quinolinol were used, leading to the substitution products [17]-[19] as mixtures of regioisomers (Eq. 

Shibasaki developed the first catalytic enantioselective meso-epoxide ringopening reaction with 4-methoxyphenol (Scheme 2.15). ° This reaction was first found to be promoted by chiral gallium(m) lithium(i) bis(binaphtholate) (19), although the chemical yield was modest (31-75% yield) even with the... 

The second P-0-4 dimer submitted to reaction with dioxygen (10 bar) at room temperature in the presence of Co(II) salen as the catalyst was l-(3,4-dimethoxyphenyl)-(2-methoxyphenoxy)ethane-l-ol 23, also prepared according to Landucci (22). In the same reaction conditions, again, veratric add methyl ester 4 was recognized after methylation, derived from vanillic acid methyl ester 6 present in the oxidation reaction mixture. The other component of the methylated mixture was 1,2-dimethoxy-benzene 22, derived from ortho-methoxyphenol 20. 

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