1: With n-butyllithium T=-78 - 20°C; 2: With hydrogenchloride in methanol Heating; 3: With N,N,N',N',N'',N''-hexamethylphosphoric triamide; sodium hydride; dimethyl sulfoxide

1: (rac)-4,4'-dihydroxy-7,7'-dimethoxy-5,5'-dimethyl-2H,2'H-8,8'-bichromene-2,2'-dione With sodium hydride in N,N,N',N',N'',N''-hexamethylphosphoric triamide 2: dimethyl sulfate in N,N,N',N',N'',N''-hexamethylphosphoric triamide T=20°C; 2 h;

1.1: 17 percent / FeCl3/SiO2 / 20 h / 60 °C 2.1: n-BuLi / hexane; tetrahydrofuran / 0.75 h / -78 °C 2.2: 75 percent / hexane; tetrahydrofuran / 1.5 h / -78 - 20 °C 3.1: 67 percent / aq. HCl / methanol / 13 h / Heating 4.1: NaH / hexamethylphosphoric acid triamide 4.2: 59 percent / hexamethylphosphoric acid triamide / 2 h / 20 °C View Scheme

1: 54 percent / DEAD, n-Bu3P / tetrahydrofuran / 42 h / Ambient temperature 2: 1.) n-BuLi, 2.) CuCN-TMEDA, 3.) O2 3: 90 percent / H2 / 10percent Pd/C / ethyl acetate / 12 h 4: 92 percent / pyridine / 8 h / 0 °C 5: 96 percent / NaI / acetone / 3 h / Heating 6: Zn, EtOH / 1 h / Heating 7: 93 percent / pyridine / 2 °C 8: 68 percent / TiCl4 / benzene / 4 h / Heating 9: 85 percent / pyridine, 4-DMAP / 8 h / 50 °C 10: t-BuOK / 2-methyl-propan-2-ol / 2 h / 60 °C 11: 1.) NaH / 1.) HMPA, RT, 2.) HMPA, RT, 20 min View Scheme

1.1: n-BuLi / hexane; tetrahydrofuran / 0.75 h / -78 °C 1.2: 75 percent / hexane; tetrahydrofuran / 1.5 h / -78 - 20 °C 2.1: 67 percent / aq. HCl / methanol / 13 h / Heating 3.1: NaH / hexamethylphosphoric acid triamide 3.2: 59 percent / hexamethylphosphoric acid triamide / 2 h / 20 °C View Scheme

1.1: 67 percent / aq. HCl / methanol / 13 h / Heating 2.1: NaH / hexamethylphosphoric acid triamide 2.2: 59 percent / hexamethylphosphoric acid triamide / 2 h / 20 °C View Scheme

1: 85 percent / pyridine, 4-DMAP / 8 h / 50 °C 2: t-BuOK / 2-methyl-propan-2-ol / 2 h / 60 °C 3: 1.) NaH / 1.) HMPA, RT, 2.) HMPA, RT, 20 min View Scheme

1: t-BuOK / 2-methyl-propan-2-ol / 2 h / 60 °C 2: 1.) NaH / 1.) HMPA, RT, 2.) HMPA, RT, 20 min View Scheme

1: 93 percent / pyridine / 2 °C 2: 68 percent / TiCl4 / benzene / 4 h / Heating 3: 85 percent / pyridine, 4-DMAP / 8 h / 50 °C 4: t-BuOK / 2-methyl-propan-2-ol / 2 h / 60 °C 5: 1.) NaH / 1.) HMPA, RT, 2.) HMPA, RT, 20 min View Scheme

1: 68 percent / TiCl4 / benzene / 4 h / Heating 2: 85 percent / pyridine, 4-DMAP / 8 h / 50 °C 3: t-BuOK / 2-methyl-propan-2-ol / 2 h / 60 °C 4: 1.) NaH / 1.) HMPA, RT, 2.) HMPA, RT, 20 min View Scheme