[CH3:1][N:2]([CH2:10][CH:11]=O)[C:3](=[O:9])[O:4][C:5]([CH3:8])([CH3:7])[CH3:6].Cl.Cl.[CH2:15]([C:19]1([N:25]([CH3:27])[CH3:26])[CH2:24][CH2:23][NH:22][CH2:21][CH2:20]1)[CH2:16][CH2:17][CH3:18].C(B)#N.[Na].CO.C(Cl)(Cl)Cl>CO.C(O)(=O)C>[CH2:15]([C:19]1([N:25]([CH3:27])[CH3:26])[CH2:24][CH2:23][N:22]([CH2:11][CH2:10][N:2]([CH3:1])[C:3](=[O:9])[O:4][C:5]([CH3:8])([CH3:7])[CH3:6])[CH2:21][CH2:20]1)[CH2:16][CH2:17][CH3:18]A solution of 4.73 g (1 eq) tert-butyl methyl(2-oxoethyl)carbamate in 20 ml methanol was added to a solution of 7 g (1 eq) 4-butyl-N,N-dimethylpiperidin-4-amine bis hydrochloride in 50 ml methanol at room temperature and the reaction mixture obtained was stirred for 50 min at room temperature. 3.43 g (2 eq) sodium cyanoboron hydride were added in portions to this reaction mixture and it was then stirred for 12 h at room temperature. The reaction course was monitored by thin-layer chromatography (20% MeOH/CHCl3). Once the conversion was complete, the reaction mixture was cooled to 0° C. and adjusted to a pH of ˜5 with acetic acid. 2 g tert-butyl formylmethyl methylcarbamate and 1.7 g sodium cyanoboron hydride were again added and the reaction mixture was stirred for a further 60 min at room temperature. The methanol was then distilled off, 100 ml saturated NaHCO3 solution were added and the mixture obtained was extracted with ethyl acetate (2×200 ml) and the combined organic phases were dried over Na2SO4. Following removal of the solvent under reduced pressure, 10.5 g of crude product were obtained in the form of a pale yellow oil.
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