Ammonia → tert-Butyl 4-(methylamino)piperidine-1-carboxylate

Participants

Reaction Steps

To tert-butyl 4-oxo-1-piperidinecarboxylate (3.99 g, 20 mmol) was added ethanol (30 ml), and methylamine hydrochloride (2.70 g, 40 mmol), triethylamine (5.6 ml, 40 mmol) and titanium(IV)isopropoxide (11.8 ml, 40 mmol) were added under ice-cooling with stirring, and the mixture was stirred at room temperature for 8 hr. Then, to the reaction mixture was added sodium borohydride (1.14 g, 30 mmol), and the mixture was stirred at room temperature for 15 hr. To the reaction mixture was added 28% aqueous ammonia, and the reaction solution was filtered off through celite. The filtrate was concentrated under reduced pressure, water was added to the residue, and the mixture was extracted with dichloromethane-ethanol=5:1 mixed solvent, and dried over anhydrous magnesium sulfate. The insoluble material was filtered off, and the solution was concentrated under reduced pressure. The obtained oil was purified by silica gel column chromatography (dichloromethane-methanol) to give the title compound (2.46 g, yield 57%) as a pale-yellow oil.

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