PEG 400-Catalyzed C3 & O-Alkylation Reactions of 4-Hydroxycoumarin-A Study

PEG-400 has been found to be an efficient recyclable catalyst/solvent system for C3- and O-alkylation of 4-hydroxycoumarin with various electronically and structurally divergent alcohols with moderate to good yield of products. For the C3-alkylation using styrenes required Zn(OAc)2.2H2O (5 mol%) in PEG-400 at 70 °C. For the O-alkylation of 4-hydroxycoumarin with acetates required PEG-400 at 60 °C. This process offered a gentle and uncomplicated way to obtain multi-substituted pyranocoumarins, as well. This protocol's benefits include its wide use, moderate environment, low cost, reusable catalyst (PEG-400), and ease of usage due to the only byproducts being acetic acid and water, respectively.