Vinyl-methoxyphenol

From the molecular beam MS of the pyrolysis products of the P/N fractions, a number of phenolic compounds were detected guaiacol (2-methoxyphenol) (m/z 124), catechols (m/z 110), isomers of substituted 2-methoxyphenols with alkyl groups such as methyl (m/z 138), vinyl (m/z 150), 3-hydroxy-propen(l)-yl (m/z 180), allyl (m/z 164), hydroxyethyl (m/z 168), and ethyl (152), most likely in the para position. In addition, a few carbohydrate-derived components are also present in this fraction such as furfuryl alcohol and other furfural derivatives. 

Several years ago, we were studying aromatic vinylation reactions using stoichiometric amounts of main element Lewis acids for example, phenols were o-vinylated with acetylene in the presence of SnCU and Bu3N. As an extension, we started to examine catalytic phenol alkylation, in which allenes were found to dimerize in the presence of palladium and phenol catalysts (Scheme 5). ° When 1,2-undecadiene was treated with Pd2(dba)3 (5 mol%), (p-io )3 (15 mol%), and p-nitrophenol (10 mol%) in refluxing THF for 12 h, (9 , 12 )-10-methyl-11-methylene-9,12-icosadiene was obtained in quantitative yield (Scheme 5). The added phenol played an important role, and no reaction took place in its absence. This reaction was effectively promoted by phenol having an electron-withdrawing group, p-nitrophenol however, the yield decreased when phenol, alkylphenol, or methoxyphenol was used. Because acetic acid also promoted the reaction, phenol was considered to function as Bronsted acid. 

In an analogous fashion, use of the 7r-bonds of vinyl ethers, vinyl sulfides, and electron-rich styrenes as nucleophiles has been developed as a surprisingly versatile anodic C-C bond-forming reaction, particularly for the synthesis of complex neolignan structures. Early controlled-potential electrolysis studies on pam-methoxyphenol and vinyl ethers gave the corresponding dihydrobenzofuran acetals in what is formally a [3 2]-... 

Main pyrolysate 4-vinyl phenol 4-vinlyl-2-methoxyphenol 4-vinyl-2,6-dimethoxyphenol... 

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)... 

The ROMP of cyclooctene-5-methacrylate and its copolymerization with cyclooctadiene is catalyzed by Ru(=CHCH=CPh2)(Cl)2(PCy3)2 in the presence of p-methoxyphenol as radical inhibitor. The double bonds in the methacrylate groups are inert towards metathesis. After chain transfer with ethyl vinyl ether to release the polymer from the ruthenium centre, it can be cross-linked by radical polymerization through the methacrylate side-chains (Maughon 1995). 

The correctness of the assumption that the parent vinyl carboxylic acid of LXIII must have the structure LXIV was shown by the oxidation of LXIV to 4,5,5 -tricarboxy-2,2 -dimethoxydiphenyl ether (LXV) and comparison with the compound synthesized by the Ullmann condensation of 4-iodo-5-methoxyphthalic acid with isovanillic acid (69) or by the condensation of 3-methyl-4-acetyl-6-methoxyphenol with 3-bromoanisic acid followed by oxidation (69). The natural LXV and the synthetic compound were identical in all respects. When the three degradation products, LXIV, LIX and trimethylamine, were pieced together the structure LXVI for bebeerine was arrived at, the positions of the phenolic groups being assigned arbitrarily. 

Fig. 13 DIB-mediated methoxylative phenol dearomatization/Diels-Alder cyclodimeiization cascade reaction of 5-fluoro-2-methoxyphenol, followed by substitution of the vinylic fluorine atom by conjugate addition/elimination reactions with amines...

In the first alternative, trichloroethane is prepared by the liquid phase chlorination of vinyl chloride at 30—SO C under pressure. In the second alternative, trichloroethane is obtained by liquid phase chlorination of ethylene dichloride at about 60°C in the presence of aluminium chloride as catalyst. The trichloroethane is then dehydrochlorinated by agitating with an aqueous suspension of calcium hydroxide at about 50 C, Crude vinylidene chloride distills off as it is formed and is then purified by distillation under pressure. The dehydrochlorination of trichloroethane may also be accomplished by heating at 400°C. Vinylidene chloride is a colourless liquid (b.p. 32" C). It is rather difficult material to handle since it readily polymerizes on standing. Polymerization occurs rapidly on exposure to air, water or light but even storage under an inert atmosphere does not completely prevent polymer formation. The monomer is therefore commonly inhibited with a phenol, such as p-methoxyphenol, which is removed by distillation or alkali-washing before polymerization. 

---