1: 100 percent / Zn, AcOH / 24 h / Heating 2: 99 percent / ZnCl2 / acetic acid / 2 h / Heating 3: 99 percent / Na2Cr2O7*H2O / acetic acid / 1 h / Heating 5: 1.) HCl, 2.) NaBH4 / 2.) DMSO 6: 94 percent / HBr, HOAc / 3.5 h / Heating View Scheme