1.1: pyridine / 1 h / 0 °C / Cooling with ice 2.1: N-ethyl-N,N-diisopropylamine / dichloromethane / 1.5 h / 0 °C / Cooling with ice 3.1: 2,6-di-tert-butyl-4-methylpyridine / dichloromethane / 0.33 h / 20 °C / Inert atmosphere; Molecular sieve 3.2: 1 h / 0 - 20 °C / Inert atmosphere; Molecular sieve 4.1: pyridine / 20 °C 5.1: methanol; dichloromethane / 0.5 h 5.2: Dowex H+ View Scheme

1.1: sodium methylate / methanol / 0.5 h / 20 °C / pH 10 1.2: Dowex H+ 2.1: toluene-4-sulfonic acid / N,N-dimethyl-formamide; acetonitrile / 1 h / 20 °C 3.1: pyridine / 1 h / 0 °C / Cooling with ice 4.1: water; acetic acid / dichloromethane / 50 h / 20 - 50 °C 5.1: 2,6-di-tert-butyl-4-methylpyridine / dichloromethane / 0.33 h / 20 °C / Inert atmosphere; Molecular sieve 5.2: 1 h / 0 - 20 °C / Inert atmosphere; Molecular sieve 6.1: pyridine / 20 °C 7.1: methanol; dichloromethane / 0.5 h 7.2: Dowex H+ View Scheme

1.1: trimethylsilyl trifluoromethanesulfonate / dichloromethane / -20 °C 2.1: sodium methylate / methanol / 0.5 h / 20 °C / pH 10 2.2: Dowex H+ 3.1: toluene-4-sulfonic acid / N,N-dimethyl-formamide; acetonitrile / 1 h / 20 °C 4.1: pyridine / 1 h / 0 °C / Cooling with ice 5.1: water; acetic acid / dichloromethane / 50 h / 20 - 50 °C 6.1: 2,6-di-tert-butyl-4-methylpyridine / dichloromethane / 0.33 h / 20 °C / Inert atmosphere; Molecular sieve 6.2: 1 h / 0 - 20 °C / Inert atmosphere; Molecular sieve 7.1: pyridine / 20 °C 8.1: methanol; dichloromethane / 0.5 h 8.2: Dowex H+ View Scheme

1.1: water; acetic acid / dichloromethane / 50 h / 20 - 50 °C 2.1: 2,6-di-tert-butyl-4-methylpyridine / dichloromethane / 0.33 h / 20 °C / Inert atmosphere; Molecular sieve 2.2: 1 h / 0 - 20 °C / Inert atmosphere; Molecular sieve 3.1: pyridine / 20 °C 4.1: methanol; dichloromethane / 0.5 h 4.2: Dowex H+ View Scheme

1.1: 2,6-di-tert-butyl-4-methylpyridine / dichloromethane / 0.33 h / 20 °C / Inert atmosphere; Molecular sieve 1.2: 1 h / 0 - 20 °C / Inert atmosphere; Molecular sieve 2.1: pyridine / 20 °C 3.1: methanol; dichloromethane / 0.5 h 3.2: Dowex H+ View Scheme

1.1: N-ethyl-N,N-diisopropylamine / dichloromethane / 1.5 h / 0 °C / Cooling with ice 2.1: 2,6-di-tert-butyl-4-methylpyridine / dichloromethane / 0.33 h / 20 °C / Inert atmosphere; Molecular sieve 2.2: 1 h / 0 - 20 °C / Inert atmosphere; Molecular sieve 3.1: pyridine / 20 °C 4.1: methanol; dichloromethane / 0.5 h 4.2: Dowex H+ View Scheme

1.1: 2,6-di-tert-butyl-4-methylpyridine / dichloromethane / 0.33 h / 20 °C / Inert atmosphere; Molecular sieve 1.2: 1 h / 0 - 20 °C / Inert atmosphere; Molecular sieve 2.1: pyridine / 20 °C 3.1: methanol; dichloromethane / 0.5 h 3.2: Dowex H+ View Scheme

1.1: toluene-4-sulfonic acid / N,N-dimethyl-formamide; acetonitrile / 1 h / 20 °C 2.1: pyridine / 1 h / 0 °C / Cooling with ice 3.1: water; acetic acid / dichloromethane / 50 h / 20 - 50 °C 4.1: 2,6-di-tert-butyl-4-methylpyridine / dichloromethane / 0.33 h / 20 °C / Inert atmosphere; Molecular sieve 4.2: 1 h / 0 - 20 °C / Inert atmosphere; Molecular sieve 5.1: pyridine / 20 °C 6.1: methanol; dichloromethane / 0.5 h 6.2: Dowex H+ View Scheme

1.1: pyridine / 1 h / 0 °C / Cooling with ice 2.1: water; acetic acid / dichloromethane / 50 h / 20 - 50 °C 3.1: 2,6-di-tert-butyl-4-methylpyridine / dichloromethane / 0.33 h / 20 °C / Inert atmosphere; Molecular sieve 3.2: 1 h / 0 - 20 °C / Inert atmosphere; Molecular sieve 4.1: pyridine / 20 °C 5.1: methanol; dichloromethane / 0.5 h 5.2: Dowex H+ View Scheme

1.1: trimethylsilyl trifluoromethanesulfonate / dichloromethane / -20 °C 2.1: sodium methylate / methanol / 0.5 h / 20 °C / pH 10 2.2: Dowex H+ 3.1: toluene-4-sulfonic acid / N,N-dimethyl-formamide; acetonitrile / 1 h / 20 °C 4.1: pyridine / 1 h / 0 °C / Cooling with ice 5.1: water; acetic acid / dichloromethane / 50 h / 20 - 50 °C 6.1: 2,6-di-tert-butyl-4-methylpyridine / dichloromethane / 0.33 h / 20 °C / Inert atmosphere; Molecular sieve 6.2: 1 h / 0 - 20 °C / Inert atmosphere; Molecular sieve 7.1: pyridine / 20 °C 8.1: methanol; dichloromethane / 0.5 h 8.2: Dowex H+ View Scheme