1: oxalyl chloride, dimethylsulfoxide / CH2Cl2 / 0.5 h / -78 °C 2: 1.) 18-crown-6, <(CH3)3Si>2NK (KHMDS) / 1.) THF, toluene, -78 deg C, 5 min, 2.) -78 deg C, 45 min View Scheme

1: 1.) NaH / 1.) THF 2.) reflux, 16 h 2: oxalyl chloride, dimethylsulfoxide / CH2Cl2 / 0.5 h / -78 °C 3: 1.) 18-crown-6, <(CH3)3Si>2NK (KHMDS) / 1.) THF, toluene, -78 deg C, 5 min, 2.) -78 deg C, 45 min View Scheme

oxalyl dichloride; dimethyl sulfoxide; triethylamine 1) -78 deg C, CH2Cl2, 0.5h, 2a) 0 deg C, CH2Cl2, 2b) r.t., 45h; Yield given. Multistep reaction. Title compound not separated from byproducts;

in dichloromethane

18-crown-6 ether; potassium hexamethylsilazane 1.) THF, toluene, -78 deg C, 5 min, 2.) -78 deg C, 45 min; Yield given. Multistep reaction. Yields of byproduct given;