Convenient Synthesis of 1-Aryl-dihydroxyisochromans Exhibiting Antioxidant Activity

Several 1-aryl-hydroxy and dihydroxyisochromans were synthesized by a two-steps procedure based on the oxa-Pictet-Spengler reaction performed for the first time in dimethyl carbonate (DMC) from phenethyl alcohols and substituted benzaldehydes followed by the regioselective aromatic hydroxylation/oxidative aromatic demethylation with 2-iodoxybenzoic acid (IBX)/sodium dithionite (Na2S2O4) system. Some of them showed a novel pattern of hydroxylation degree into A ring. All synthesized isochromans were tested about their radical scavenging activity by 2,2-diphenyl-2-picrylhydrazyl radical (DPPH center dot) method. Experimental results showed that dihydroxyisochromans were more active than the corresponding phenolic or guaiacolic parent compounds confirming the key role of the catecholic moiety for the antioxidant activity.