1: 3-bromo-6-[(Z)-2-butenyl]-5-iodo-2(2H)-pyranone With chloro-trimethyl-silane; ethylene dibromide; zinc in tetrahydrofuran T=20°C; 2: tetramethylstannane With copper(l) iodide; bis (triortho-tolylphosphine)palladium(II) chloride in 1-methyl-pyrrolidin-2-one T=80°C; 20 h;