Synthesis and DPPH Radical Scavenging Activity of Prenylated Phenol Derivatives

Abstract

The synthesis of twenty six prenylated phenols derivatives is reported. These compounds were obtained under mild conditions via Electrophilic Aromatic Substitution (EAS) coupling reactions between phenol derivatives containing electron-donor subtituents and 3-methyl-2-buten-1-ol using BF3·OEt2. Dialkylations were also produced with this method. The formation of a chroman ring by intramolecular cyclization between a sp2 carbon from the prenyl group with the hydroxyl substituent in the ortho position occurred with some phenols. All the synthesized compounds were evaluated as antioxidants according to a DPPH radical scavenging activity assay. IC50 values of five synthesized compounds indicated they were as good antioxidants as Trolox™.

Synthesis, Anti-Phytopathogenic and DPPH Radical Scavenging Activities of C-Prenylated Acetophenones and Benzaldehydes

“…The radical scavenging activity of the prenylated compounds and starting materials towards the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical was measured as described 35 , with modifications to adapt the screen to 96-well plates. Stock solutions of each compound were prepared in methanol at a 1 mM concentration (10 mL).…”

Synthesis and Biological Evaluation of New 1,3-Thiazolidine-4-one Derivatives of 2-(4-Isobutylphenyl)propionic Acid

“…In methanol solution DPPH has an intense violet color with a UV-Vis absorption band at 517 nm, and it becomes pale yellow or colorless when neutralized in the presence of proton donating agents [27]. The DPPH radical scavenging ability (%) of samples at concentrations of 487.8 µg/mL is presented in Tables 4 and 5.…”

“…The radical scavenging activity of the tested compounds towards the radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) was measured as described in [27] with slight modifications. DPPH in methanol (4 mL, 15 µM) was added to the test compounds (100 µL) prepared from stock solution (20 mg/mL).…”

Rapid Method of Friedel-Crafts Alkylation of Phloroglucinol by Microwave in Dry Media and Reusable Catalyst

“…Such an important structural motif needs a general strategy for its preparation, particularly for systems in which other aromatic hydroxyl residues are differentiated or present, as is often the case with natural therapeutic products containing this pharmacophore 8 . Terpenylphenols are isolated from natural sources with very low yield, and for that reason during the past few decades considerable research effort has focused on obtaining these compounds by synthesis.…”

“…Their structural complexity when phloroglucinol is alkylated draws attention; because in general, it is a challenge to attempt to incorporate nonpolar chains in a tri-substituted aromatic ring with OH groups (electron donating group).Among the most common synthetic strategies reported for the introduction of nonpolar chains in an aromatic ring (C-Alkylation) are: Friedel-Crafts reactions, Michael addition and multistep processes consisting of a neutral-pathway leading to the early O-alkylation, followed by a series of ionic rearrangements resulting finally in C-alkylations. 9 There are many publications that report different methods for accomplishing these coupling reactions in the synthesis of prenyl phenols and geranylphenols 8,[10][11][12] , most with low yields and using highly toxic homogeneous and heterogeneous (solid) catalysts such as HF, H 2 SO 4 , AlCl 3 , or BF 3 13,14 . But there are no reports of Friedel-Crafts allylation of the phloroglucinol molecule, via microwave mediated Electrophilic Aromatic Substitution (EAS).…”