1: 77 percent / trisdimethylamino sulfonyl trimethylsilyldifluoride; water / dimethylformamide / 26 h / 0 °C 2: 84 percent / aq. NaOH / tetrahydrofuran / 30 h / 20 °C 3: 2,4,6-trichlorobenzoyl chloride; triethylamine; DMAP / tetrahydrofuran; toluene / 25.5 h / 0 - 20 °C 4: Me2BBr / CH2Cl2 / 1 h / -78 °C View Scheme