tetrabutyl ammonium fluoride; water in tetrahydrofuran T=20°C; 4 h;

1.1: 52 percent Spectr. / Ti(O-i-Pr)4; i-PrMgCl / diethyl ether / 2.5 h / -78 - -50 °C 2.1: Br2; Na2SO3 / CH2Cl2; methanol / -78 °C 3.1: 3.49 g / MeONa / methanol; tetrahydrofuran / 3 h / 0 - 20 °C 4.1: NaN[SiMe3]2 / tetrahydrofuran / 1 h / -78 °C 4.2: 86 percent / tetrahydrofuran / -78 - 20 °C 5.1: 90 percent / Pd(PPh3)2Cl2; CuI; Et3N / tetrahydrofuran / 0.5 h / 0 °C View Scheme