tetrakis(triphenylphosphine) palladium(0) in tetrachloromethane 12 h; Ambient temperature;

toluene-4-sulfonic acid in dichloromethane T=25°C; 0.5 h;

amberlyst-15 in chloroform T=-20°C; Cyclization; dehydration;

diisobutylaluminium hydride in tetrahydrofuran; cyclohexane T=-78°C; 1 h;

1: NaBH4; CeCl3*7H2O / methanol 2: 100 percent / Amberlyst-15 / CHCl3 / -20 °C View Scheme

1: 100 percent / DIBAL-H / toluene / 7 h / -40 °C 2: 82 percent / Et3N, 4-(dimethylamino)pyridine / CH2Cl2 / 2 h / 0 °C 3: 96 percent / triethylammonium fluoride / acetonitrile / 12 h / 60 °C 4: 30 percent / N-BuLi, Pd(DIPHOS)2, DIPHOS / tetrahydrofuran / 48 h / Heating; other alkoxides View Scheme

1: 96 percent / triethylammonium fluoride / acetonitrile / 12 h / 60 °C 2: 30 percent / N-BuLi, Pd(DIPHOS)2, DIPHOS / tetrahydrofuran / 48 h / Heating; other alkoxides View Scheme

N,N,N',N',N'',N''-hexamethylphosphoric triamide; n-butyllithium; bis[1,2-bis(diphenylphosphino)ethane]palladium(0); O,O,O',O'-tetramethyl O,O'-thiodi-p-phenylene phosphorothioate in tetrahydrofuran 1.) -78 deg C, 30 min, 2.) reflux, 48 h;