4-(N-Boc-amino)piperidine → {1-[2-(7-Methoxy-quinoxalin-2-ylsulfanyl)-ethyl]-piperidin-4-yl}-carbamic acid tert-butyl ester

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Reaction Steps

Piperidin-4-yl-carbamic acid tert-butyl ester (2.82 g, 14.09 mmol, 1.5 eq) is added at room temperature to a stirred solution of (7-methoxy-quinoxalin-2-ylsulfanyl)-acetaldehyde (2.2 g, 9.39 mmol, 1.0 eq) in 1,2-dichloroethane (80 mL), followed by sodium triacetoxyborohydride (3.98 g, 18.78 mmol, 2.0 eq). After 15 hours stirring at room temperature, the reaction mixture is extracted with dichloromethane (3×60 mL) and a saturated sodium hydrogen carbonate aqueous solution (60 mL). The combined organic layers are dried over sodium sulfate, filtered and concentrated to give a crude product that is purified by column chromatography (silica gel, eluent: ethyl acetate:hexane, 1:1, v/v) to give a yellow solid that is further recrystallized with ethyl acetate:hexane (1:6, v/v) to afford {1-[2-(7-methoxy-quinoxalin-2-ylsulfanyl)-ethyl]-piperidin-4-yl}-carbamic acid tert-butyl ester as light yellow needles (2.6 g, 66% yield).

Provenance & Evidence