Methylamine → Benzyl 4-((tert-butoxycarbonyl)(methyl)amino)piperidine-1-carboxylate

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Reaction Steps

A mixture of commercially available 4-oxo-piperidine-1-carboxylic acid benzyl ester (4.67 g, 20 mmol) and methylamine (8 M in EtOH, 12.5 mL, 100 mmol) in dioxane (total volume of 100 mL) is stirred at r.t. for 15 min. NaBHAc3 (6.4 g, 30 mmol) is added and the mixture is stirred for 15 h. The mixture is quenched with 1 M aq. NaOH (30 mL) and stirred at r.t. for 30 min. The mixture is diluted with water (50 mL) and extracted with CH2Cl2 (3×75 mL). The organic extracts are dried (Na2SO4), filtered and evaporated. The residue is dissolved in ether (200 mL) and TEA (1.4 mL, 10 mmol) and, subsequently, a solution of di-tert.butyl-dicarbonat (3.82 g, 17.5 mmol) in ether (10 mL) are added. The mixture is stirred at r.t. for 15 h and quenched with 1 M aq. NaOH (30 mL). The phases are separated and the organic phase is washed with 1 M aq. NaOH (30 mL), 1 M aq. KHSO4 (2×30 mL) and sat. aq. NaCl (30 mL). The organic phase is dried (Na2SO4), filtered and evaporated to provide the title compound.

Provenance & Evidence