2.5 g of 7-hydroxy-benzo[1,3]dioxole-5-carboxylic acid, 6.8 g of 1-(2-bromo-ethyl)-3-methyl-benzene and 7.6 g of potassium carbonate were stirred in 100 ml of anhydrous DMF for 10 h at 80° C. Then another 1.4 g of 1-(2-bromo-ethyl)-3-methyl-benzene and 1.5 g of potassium carbonate were added and the mixture was stirred for 5 h at 90° C. The solvent was removed in vacuo and the residue dissolved in 200 ml of water and 200 ml of EA. The organic layer was separated, washed with 100 ml of a saturated aqueous sodium carbonate solution, dried with magnesium sulfate and evaporated to yield 4.5 g of the title compound.
