Sodium borohydride → 1-[2-(3,4-dimethoxyphenyl)-2-hydroxyethyl]-4-(3,4-dihydro-2,2-dioxo-1H-2,1,3-benzothiadiazin-3-yl)-piperidine

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Reaction Steps

In 150 ml of methanol, 2.2 g of 1-(3,4-dimethoxybenzoylmethyl)-4-(3,4-dihydro-2,2-dioxo-1H-2,1,3-benzothiadiazin-3-yl)-piperidine is suspended. While this suspension is stirred at room temperature, 1.0 g of sodium borohydride is added thereto by portions over a period of four hours. The mixture is stirred overnight at room temperature and 400 mg of sodium borohydride is added thereto. Then, the mixture is stirred overnight. The reaction solution is concentrated under reduced pressure. The residue is mixed with 100 ml of water and adjusted to pH 9.3 with concentrated hydrochloric acid. The resultant mixture is extracted with chloroform. The organic layer is washed with water, dried and freed from the solvent by distillation to obtain a syrup as a residue. This residue is crystallized by adding methanol thereto. The crystals are separated by filtration to obtain 1.93 g of crude crystals. The crude crystals are recrystallized from ethanol to obtain 1.45 g of 1-[2-(3,4-dimethoxyphenyl)-2-hydroxyethyl]-4-(3,4-dihydro-2,2-dioxo-1H-2,1,3-benzothiadiazin- 3-yl)-piperidine (Compound No. 10).

Provenance & Evidence