1: NaClO2, NH2SO3H / dioxane; H2O 2: diethyl ether 3: DDQ / CH2Cl2; H2O 4: oxalyl chloride in DMSO, Et3N 5: 65 percent / n-BuLi / 2-methyl-propan-2-ol; tetrahydrofuran 6: 17 percent / p-TsOH*H2O / ethanol; H2O 7: 80 percent / 1N aq. NaOH View Scheme