To a suspension of (S)-6-aza-spiro[2.5]octan-4-ol hydrochloride (intermediate 2) 0.16 g (1 mmol) in CH2Cl2 (5 ml) was added Et3N 0.14 ml (1 mmol) and AcOH 0.11 ml (2 mmol) followed by a solution of 5-oxo-4-(3-oxo-propyl)-[1,4]diazepane-1-carboxylic acid tert-butyl ester 0.34 g (1 mmol) in CH2Cl2 (5 ml) and finally sodium triacetoxyborohydride 0.25 g (1 mmol). The mixture was stirred for 1 h after which time sat. aq. NaHCO3. solution was added, the reaction extracted with in CH2Cl2, dried (Na2SO4) and concentrated. The residue was taken up in 1 M HCl solution in dioxane (10 ml), stirred for 10 minutes before the solvent was evaporated. The residue was then dissolved in sat. aq. NaHCO3. solution the water removed by evaporation, and the solid extracted with CH2Cl2:MeOH (9:1). Concentration afforded the title compound 0.2 g (71%) as yellow oil. MS: 282.1 (MH+).
