1.1: N-ethyl-N,N-diisopropylamine; sulfur trioxide pyridine complex / toluene; dimethyl sulfoxide / 1 h / 0 °C / |Inert atmosphere 1.2: 1 h / 0 °C 2.1: water; sodium dithionite / methanol / 0 °C / |Cooling 2.2: 2 h / 25 °C 3.1: hydrogenchloride; water / 3 h / |Reflux 3.2: |Reflux 3.3: 3 h / 10 - 20 °C 4.1: methanol / 48 h / 70 °C View Scheme

hydrogen; palladium on activated charcoal