1: 81 percent / Sn, HCl aq. / 4 h / 50 °C 2: Et3N / CH2Cl2 / 0.25 h 3: 29 percent / TFA / 3 h / Ambient temperature View Scheme

1: 81 percent / Sn, HCl aq. / 4 h / 50 °C 2: CH2Cl2 / 0.25 h / Ambient temperature 3: 1.) NaH, 2.) 10percent K2CO3 aq. / 1.) DMF, RT, 30 min, 2.) MeOH, reflux, 15 min 4: 13 percent / Et3N / CH2Cl2 / 0.25 h 5: TFA / 1.) reflux, 2.) 50 deg C, 30 min View Scheme