1.1: 2,6-dimethylpyridine / dichloromethane / 4 h / 0 - 5 °C 1.2: 3 h / 5 °C 2.1: tetrabutyl ammonium fluoride / tetrahydrofuran / 4 h / 20 °C 3.1: 2,4,6-trichlorobenzoyl chloride; triethylamine / tetrahydrofuran / 1 h / 0 °C 3.2: 10.33 h / 20 °C 4.1: trifluoroacetic acid / dichloromethane / 1 h / -20 - 0 °C View Scheme

1: With 2,6-dimethylpyridine in dichloromethane T=0 - 5°C; 4 h; 2: With water; acetic acid in tetrahydrofuran T=5°C; 3 h;

Multi-step reaction with 3 steps 1.1: n-butyllithium; diisopropylamine / tetrahydrofuran / 1.75 h / -78 - 40 °C1.2: 0.08 h / -78 °C2.1: formic acid / diethyl ether / 10 h / 5 - 20 °C3.1: [bis(acetoxy)iodo]benzene; water / tetrahydrofuran / 0.67 h / 20 °C