1: methanol / Ambient temperature 2: pyridine / Ambient temperature 3: DMAP / acetonitrile / 1 h / Ambient temperature 4: Bu3SnH, VAZO / toluene / 1 h / 100 °C 5: 1.) NaOMe, MeOH, 2.) 1N aq. HCl / 1.) RT, 2 h, 2.) MeOH, RT, overnight View Scheme