toluene-4-sulfonic acid in methanol 24 h; Ambient temperature;

1.1: n-BuLi / tetrahydrofuran / 2.5 h / -78 °C 1.2: 98 percent / tetrahydrofuran / -35 - 20 °C 2.1: 95 percent / 4-methylbenzenesulfonic acid / methanol / 20 °C View Scheme

1.1: 98 percent / camphorsulfonic acid / CH2Cl2 / 0 - 20 °C 2.1: n-BuLi / tetrahydrofuran / 2.5 h / -78 °C 2.2: 98 percent / tetrahydrofuran / -35 - 20 °C 3.1: 95 percent / 4-methylbenzenesulfonic acid / methanol / 20 °C View Scheme

oxygen; sodium acetate; triphenylphosphine; palladium dichloride in N,N-dimethyl-formamide T=20°C; 48 h;

[VCl3(tetrahydrofuran)3]; zinc in dichloromethane 20 h; Ambient temperature;

(i) nBuLi, THF, (ii) /BRN= 605437/, (iii) TsOH, MeOH; Multistep reaction;