2-Methyl-1-butene → (S)-2-methyl-3-[4-(4-trifluoromethyl-phenyl)-piperazin-1-yl]-propionic acid

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Reaction Steps

(S)-2-Methyl-3-[4-(4-trifluoromethyl-phenyl)-piperazin-1-yl]-propionaldehyde (1.99 g; 6.6 mmol, prepared in accordance with Example 66) is suspended in a mixture of tert-butanol (48 mL) and water (12 mL); sodium dihydrogenphosphate (1.59 g; 13.3 mmol) and 2-methyl-butene (13.94 g; 199 mmol) are added and the resulting mixture is stirred until a solution is obtained. Sodium chlorite (1.12 g; 9.9 mmol) is added and the reaction is stirred at room temperature for one hour. The precipitate formed is filtered, is washed with water and is dried at 40° C. under 3 mbar. Aqueous sat ammonium chloride (50 mL) is added to the filtrate which is then extracted with dichloromethane (2×50 mL). The combined organic layers are washed with brine (50 mL) and concentrated under reduced pressure. The residue obtained is dried at 40° C. under 3 mbar. The enantiopure product is obtained as colourless solid (1.3 g; 4.1 mmol).

Provenance & Evidence