Tetrakis(triphenylphosphine)palladium (0) (852 mg, 0.7 mol) was added to a stirred solution of 4-bromo-3-methyl-benzoic acid tert-butyl ester from Example E31.1 (1.86 g, 6.8 mmol), 1-acetoxy-1,3-butadiene (7.5 ml, 64.5 mmol) and sodium acetate (5.69 g, 69.4 mmol) in DMA (75 ml). The mixture was heated at 140° C. for 3 h, filtered through Celite® filter agent and the filtrate was concentrated in vacuo. The residue was purified by flash chromatography on silica gel (eluant; 20% EtOAc:80% pet. ether) to yield the title compound (1.54 g, 74%).
