sulfuric acid in tetrahydrofuran 2 h; Heating; Yield given;

2: 5percent H2SO4 / tetrahydrofuran / 2 h / Heating View Scheme

1: 1.) NaH / 1.) DMF 2: 1.) NaHPO4, 6percent natrium amalgame, 2.) p-toluenesulfonic acid / 1.) methanol, 40 min, 2.) ethanol, water, 11 h, reflux View Scheme

disodium hydrogenphosphate; sodium amalgam; toluene-4-sulfonic acid 1.) methanol, room temp., 30 min, 2.) ethanol, reflux, 20 h; Yield given. Multistep reaction. Yields of byproduct given;