18-crown-6 ether; potassium tert-butylate in tetrahydrofuran; N,N,N',N',N'',N''-hexamethylphosphoric triamide

1: O3 / methanol; ethyl acetate / -78 °C 2: LAH / tetrahydrofuran 3: 36 percent / nBu3P, Br2 / dimethylformamide 4: KOtBu, 18-C-6 / tetrahydrofuran; hexamethylphosphoric acid triamide View Scheme

1: 36 percent / nBu3P, Br2 / dimethylformamide 2: KOtBu, 18-C-6 / tetrahydrofuran; hexamethylphosphoric acid triamide View Scheme