Synthesis and nmr structure determination of new linear geranylphenols by direct geranylation of activated phenols

Abstract

The known geranylhydroquinone 2, geranylorcinol 4 and the derivative (E)-4-(3,7-dimethylocta-2,6-dienyl)-5-methylbenzene-1,3-diol 5, were prepared by Electrophilic Aromatic Substitution (EAS) reactions between the corresponding phenol derivatives containing electron-donor subtituents and geraniol using BF3×OEt2 as a catalyst. In addition, spectroscopic NMR information for 4 and 5 is complemented. Furthermore, the new (E)-2-(3,7-dimethylocta-2,6-dienyl) benzene-1,3,5-triol (geranylphloroglucinol) 13, (E)-2-(3,7-dimethylocta-2,6- dienyl)-1,3,5-trimethoxybenzene 14, (E)-2-(3,7-dimethylocta-2,6-dienyl)-6- methoxyphenol 15, (E)-3-(3,7-dimethylocta-2,6-dienyl)-2-methoxyphenol 16, (E)-5-(3,7-dimethylocta-2,6-dienyl)-2-methoxyphenol 17, (E)-4-(3,7-dimethylocta- 2,6-dienyl)benzene-1,3-diol 18, (E)-3-(3,7-dimethylocta-2,6-dienyl)benzene-1,2- diol 19, (E)-4-(3,7-dimethylocta-2,6-dienyl)-5-isopropyl-2-methylphenol 20, (E)-2-(3,7-dimethylocta-2,6-dienyl)-4-isopropyl-3-methylphenol 21, (E)-2-(3,7-dimethylocta-2,6-dienyl)-4-isopropyl-5-methylphenol 22, and(E)-2-tert-butyl-4- (3,7-dimethylocta-2,6-dienyl)-5-methylphenol 23 were also prepared with this synthesis strategy. All the synthesized compounds were fully characterized and their structures were established by IR, MS and mainly NMR spectroscopic dates.