Sodium borohydride → 1-[2-(3,4-Dimethoxyphenyl)-2-hydroxyethyl]-4-(2-oxo-3,4-dihydro-2H-1,3-benzoxazin-3-yl)-piperidine

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Reaction Steps

In this example, 3.0 g of 1-(3,4-dimethoxybenzoylmethyl)-4-(2-oxo-3,4-dihydro-2H-1,3-benzoxazin-3-yl)-piperidine obtained in Example 1 is mixed with 150 ml of methanol. While this mixture is stirred at 0°-10° C., 0.8 g of sodium borohydride is added thereto over a period of 3 hours. The reaction solution is stirred overnight at room temperature. Then, the solution is further mixed with 0.4 g of sodium borohydride and stirred at room temperature for 3 hours. The white crystals deposited are separated by filtration, washed with methanol and water and dried to obtain 2.77 g of a crude product. The crude product is recrystallized from ethanol to obtain 2.52 g of the desired product.

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