Multi-step reaction with 5 steps 1: MCPBA / CH2Cl2 / 0 deg C, 1.5 h, then RT, 24 h2: 1.) NaOH / 1.) H2O, 70 deg C; 2.) H2O, 70 deg C, 2.5 h3: 67 percent / pyridine / -10 deg C, 2 h, then RT, 2 h4: 83 percent / 30percent NH4OH / N,N-dimethyl-acetamide / Ambient temperature; sealed flask5: 79 percent / Et3N / CH2Cl2 / 0.5 h / -10 - -5 °C