Sustainable Synthesis of Natural-like Hydroxylated Biphenyls as Potential Bioactive Compounds

Hydroxylated biphenyls with a C2-symmetry axis have attracted considerable interest because of the biological activity exerted by a number of natural occurring compounds containing this moiety and because of their ability to transmit conformational information in stoichiometric and catalytic processes [1]. The geometrical possibilities offered by chemical transformation of the biphenyl skeleton make it a versatile building block in drug synthesis and catalysis [2]. With the aim to synthetized new biphenyl compounds, we have considered chalcons, an important class of bioactive compounds that has attracted much interest not only from the synthetic and biosynthetic perspectives but also due to its broad interesting biological activities [3]. Chalcone is chemically 1,3-diaryl-2-propen-1-one in which the two aromatic rings are bonded by a three-carbon ?,?-unsaturated carbonyl system [4]. Our study was aimed to prepare new chalcones compounds starting from commercial 1,1'- biphenyl-4,4'-diol, an exametabolite producted from cyanobacteria. For this purpose we prepared 4,4'-dihydroxy-[1,1'-biphenyl]-3,3'-dicarbaldehyde (bis salicylaldehyde) via formylation reaction of 1,1'- biphenyl-4,4'-diol with hexamethylenetetramine in the presence of trifluoroacetic acid [5]. Claisen-Schmidt condensation of bis salicylaldeide with variously substituted acetophenones under microwaves technology provided the desired chalcons derivatives in good yields. Another class of compounds we have considered was a curcumin related biphenyls. In a previous study, we prepared dimer of OMe-dehydrozingerone D6 [6]. We found that compound D6 was more active in inhibiting malignant melanoma and neuroblastoma cells growth when compared to curcumin itself [7]. Starting from bis salicyladehyde via Claisen-Schmidt condensation in the presence of LiOH and acetone we obtained an ?, ?-unsatured keton analogue of D6. All synthesized compounds were obtained as air stable solids and easily purified by flash chromatography. Biological activity of all synthetized compounds is under evaluation.