Propenylphenols

Propenylphenoxy compounds have attracted much research. BMI—propenylphenoxy copolymer properties can be tailored through modification of the backbone chemistry of the propenylphenoxy comonomer. Epoxy resins may react with propenylphenol (47,48) to provide functionalized epoxies that may be low or high molecular weight, Hquid or soHd, depending on the epoxy resin employed. Bis[3-(2-propenylphenoxy)phthalimides] have been synthesized from bis(3-rutrophthalimides) and o-propenylphenol sodium involving a nucleophilic nitro displacement reaction (49). They copolymerize with bismaleimide via Diels-Alder and provide temperature-resistant networks. 

Of the phenols and phenyl ethers used as fragrance and flavor substances, 4-allyl-(9, R = H) and 4-propenylphenols (10 and 11, R = H) and their methyl ethers (9-11, R = CH3) occur particularly frequently in essential oils. 

A second hydroxyl or methoxyl substituent is often present 2-methoxy-4-allylphenol and 2-methoxy-4-propenylphenol are the most important compounds belonging to this category. 

It is of interest to note that 2-propenylphenol yields the spiropyran (105) on treatment with DDQ, whilst 2-(l-phenylpropenyl)phenol affords 2-methyl-3-phenylbenzofuran. 

Another occasionally useful transformation of allylphenols is the isomerization to propenylphenols by strong alkali, as in the well-known isomerization of eugenol to isoeugenol. For example, 2-methoxy-6-allylphenol (LXXI) is changed to the propenyl compound LXXII by... 

Isomerization of 2-Allylphenol to 2-Propenylphenol. 2-Allylphenol is dissolved in three times its volume of a saturated solution of potassium hydroxide in methanol part of the solvent is distilled off until the temperature of the liquid rises to 110°, and the residue is refluxed six hours at this temperature. The reaction product is washed free of the base, dried, and distilled, giving a 75% yield of 2-propenylphenol boiling over a range 110-115°/15-16 mm. The compound solidifies in the receiver, and on recrystallization from ligroin forms shining needles melting at 36.5-37° (corr.) in fused state nf> 1.5823, b.p. 230-231° at atmospheric... 

Nakatsubo F, Higuchi T (1975) Synthesis of 1,2-diarylpropane 1,3 diols and determination of their configurations Holzforschung 29 193-198 Ralph J, Ede RM, Robinson NP, Main L (1987) Reactions of /f-aryl lignin model quinone methides with anthrahydroquinone and antranol J Wood Chem Technol 7 133 160 Ralph J, Young RA (1983) Stereochemical aspects of lignin model (S aryl ether quinone methide reactions J Wood Chem Technol 3 161-182 Sarkanen KV, Wallis AFA (1973) Oxidative dimerizations of (E)- and (Z) isoeugenol (2 methoxy-4-propenylphenol) and (E) and (Z)-2,6-dimethoxy-4-propenylphenol JCS Perkin I 1973 1869-1878... 

Tollier M-T, Monties B, Lapierre C, Herve du Penhoat C, Rolando C (1986) Inhomogeneity of angiosperm lignin Comparison of the monomeric composition of lignin fractions isolated from different wood species Holzforschung Suppl 40 75-79 Wallis AFA (1973) Oxidation of (E) and (Z)-2 6-dimethoxy-4-propenylphenol with ferric chloride - a facile route to the 2-aryl ethers of 1-arylpropane 1,2 diols Aust J Chem 26 585-594... 

Vassao, D.G., Kim, S.J., Mihollan, J.K., Eichinger, D., Davin, L.B. and Lewis, N.G. (2007) A pinoresinol-lariciresinol reductase homologue from the creosote bush Larrea tridentata) catalyzes the efficient in vitro conversion of p-coumaryl/coniferyl alcohol esters into the allylphenols chavicol/eugenol, but not the propenylphenols p-anol/isoeugenol. Arch. Biochem. Biophys., 465, 209-18. 

Migrations of the double bond and carbon-skeleton rearrangements are important in the preparation of several olefinic compounds. A number of alkyl cyclopentenes are available in quantities suitable for synthetic work by the isomerization of cyclohexene and its homologs over alumina at 470- 480°. o-Allylphenol is isomerized by methanolic potassium hydroxide at 110° to o-propenylphenol (75%). Several /5, y-olefinic acids are conveniently obtained from the corresponding a /3-isomers by equilibration in basic media. The two isomeric acids are readily separated by partial esterification of the resulting mixtures since the /3,y-isomers are more easily esterified. "... 

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