1: (R)-4,4-dimethoxytetrahydro-2H-pyran-3-ol With sodium t-butanolate in tetrahydrofuran; water 2: dimethyl sulfate in tetrahydrofuran; water T=36°C; 4.33333 h; 3: With hydrogenchloride; water; sodium hydrogencarbonate more than 3 stages;

1.1: potassium tert-butylate / tetrahydrofuran / 0.75 h / 0 °C / |Inert atmosphere 1.2: 2.25 h / 0 - 20 °C 2.1: hydrogenchloride; water / tetrahydrofuran / 2.25 h / 0 - 3 °C View Scheme