triethylamine in tetrahydrofuran T=0°C; Yield given;

1: NEt3 / tetrahydrofuran / 0 °C 2: 1) BuLi / 1) THF, -78 deg C, 2) HOAc, THF, -78 deg C 3: 1) BuLi / 1) THF, -78 deg C, 2) -78 deg C to RT 4: 1) t-BuOK, 2) HF / 1) THF, RT, 2) CH3CN, RT 5: t-BuOK / tetrahydrofuran; 2-methyl-propan-2-ol / 0.25 h / 25 °C View Scheme