1: 1.) butyl-lithium, 2.) hexamethylphosphoric triamide / 1.) THF, -78 deg C, 2 h, 2.) room temperature, 3 h 2: 98 percent / sodium hydroxide / methanol; H2O / 3 h / Ambient temperature 3: 95 percent / tetrahydrofuran / 12 h 4: 87 percent / lithium hexamethyldisilazide / tetrahydrofuran; hexane / 7 h / -78 °C 5: 95 percent / lithium hexamethyldisilazide / tetrahydrofuran; hexane / 2 h / -78 °C 6: m-chloroperoxybenzoic acid, 30percent aq. hydrogen peroxide / CDCl3 / 1.) -50 deg C, 15 min, 2.) 0 deg C, 15 min 7: 37 percent / toluene / 5 h / 100 °C 8: 98 percent / sodium hydroxide / H2O; methanol / 2 h / 0 °C 9: 98 percent / lithium di-isopropylamide / tetrahydrofuran; hexane / 2 h 10: 78 percent / tetrabutylammonium fluoride / tetrahydrofuran / 2 h / 0 °C 11: 68 percent / pyridine, 30percent aq. hydrogen peroxide / CH2Cl2 / 12 h / Ambient temperature 12: 72 percent / sodium borohydride / ethanol / 3 h / 0 °C 13: 94 percent / pyridine, 4-dimethylaminopyridine / CH2Cl2 / 2 h / Ambient temperature 14: 19 percent / m-chloroperoxybenzoic acid / CH2Cl2 / 1.) -20 deg C, 1 h, 2.) 0 deg C, 12 h 15: 67 percent / aluminium isopropoxide / o-xylene / 5 h / 125 °C 16: 40 percent / 5percent aq. HF / acetonitrile / 3 h / Ambient temperature View Scheme

1: (2E,4E)-4-Methylhexa-2,4-dienylphosphonic acid diethylester With lithium diisopropyl amide in tetrahydrofuran; hexane T=-78°C; Metallation; 15 h; 2: (2R,3S,4S,5S)-7-[8-hydroxy-5,7-dimethoxy-3-methyl-4-oxo-4H-2-chromenyl]-2,4-dimethoxy-3,5-dimethylheptanal in tetrahydrofuran; hexane T=-78 - 20°C; Condensation; Horner-Wadsworth-Emmons reaction;