18-crown-6 ether; potassium tert-butylate 1.) THF, 15 min, 2.) THF, RT, 3.5 h; Yield given. Multistep reaction;

1: 36 percent / 2 N aq. KOH / ethanol; tetrahydrofuran / Ambient temperature 2: 51 percent / N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride, 4-dimethylaminopyridine / tetrahydrofuran / 18 h / Ambient temperature View Scheme

potassium hydroxide in tetrahydrofuran; ethanol Ambient temperature;