The C3 or O-alkylation of 4-hydroxycoumarin (formation of new C-C and C-O bond) is undoubtedly one of the most important and challenging reactions in synthetic chemistry due to its pharmaceutical utility. In this communication, we report sulfated tin oxide (STO)-catalyzed synthesis of arylated vinyl ethers in moderate to good isolated yields (68-93%) from the reaction of substituted phenyl acetylenes (terminal alkynes) with 4-hydroxy coumarin in polyethylene glycol (PEG 400) as solvent at 110 oC. The catalyst can be recycled up to 5 times without losing the significant yield.

One significant and elegant method for creating β-amino alcohols, which are useful intermediates for the synthesis of many different natural and synthetic pharmaceutical compounds, is to open the rings of epoxides with amines. When sulfated tin oxide catalyst (2 mol%) is present, epoxides can open their rings and react with amines to produce corresponding β-amino alcohols in good to high yields under mild circumstances. Under clean circumstances and in a short amount of time, the reaction demonstrated high regioselectivity and functioned well with both aromatic and aliphatic amines at room temperature.