1: 93 percent / dicyclohexyl-18-crown-6 ether / acetonitrile / 1.) RT, 4 h, 2.) reflux, 2 h 2: 97.7 percent / KOH / H2O; ethanol / 48 h 3: 75 percent / PPA / 2 h / 100 °C 4: NaBH4 / methanol / 16 h / Ambient temperature 5: 81 percent / 1.) p-toluenesulfonic acid, 2.) chloranil / benzene / 1.) reflux, 2 h, 2.) reflux, 24 h 6: N-bromosuccinimide, benzoyl peroxide / CCl4 / 6 h / Heating 7: 71 percent / 1.) hexamethylenetetramine, 2.) 50percent acetic acid / 1.) chloroform, reflux, 90 min, 2.) reflux, 90 min View Scheme

1: 93 percent / dicyclohexyl-18-crown-6 ether / acetonitrile / 1.) RT, 4 h, 2.) reflux, 2 h 2: 97.7 percent / KOH / H2O; ethanol / 48 h 3: 75 percent / PPA / 2 h / 100 °C 4: NaBH4 / methanol / 16 h / Ambient temperature 5: 81 percent / 1.) p-toluenesulfonic acid, 2.) chloranil / benzene / 1.) reflux, 2 h, 2.) reflux, 24 h View Scheme