1: (3-ethoxycarbonyl-2-oxopropylidene)triphenylphosphorane With sodium hydride in tetrahydrofuran T=0°C; 0.5 h; 2: chromone-3-carboxaldehyde in tetrahydrofuran domino Michael-retro-Michael-Wittig reaction; 24 h; Heating;

trimethylsilyl trifluoromethanesulfonate in dichloromethane T=0 - 20°C; Michael-retro-Michael-aldol reaction;