1.1: pyridine / 0 - 10 °C 2.1: n,N-diisopropylethylamine / CHCl3 / 20 °C 3.1: NaOMe / methanol / Heating 4.1: PPh3; DEAD / toluene / 20 °C 5.1: NaOMe / methanol / Heating 5.2: aq. AcOH / 100 °C View Scheme

1.1: pyridine / 0 - 10 °C 2.1: SO3*pyridine; Et3N / dimethylsulfoxide / 3 h / 20 °C 3.1: NaBH4 / methanol; CH2Cl2 / 20 °C 4.1: NaOMe / methanol / Heating 4.2: aq. AcOH / 100 °C View Scheme