To a stirred mixture of copper(II) sulfate pentahydrate (0.042 g, 0.17 mmol) in N,N-dimethylformamide (15 mL) was added sodium borohydride (0.037 g, 1 mmol). To the resulting suspension was added N-[5-((1R)-2-azido-1-hydroxy-ethyl)-2-chloro-phenyl]-methanesulfonamide (which was obtain in Example 25) (0.11 g, 0.38 mmol). After stirring for 20 minutes more copper(II) sulfate pentahydrate (0.042 g, 0.17 mmol) and sodium triacetoxyborohydride (0.064 g, 0.3 mmol) was added. The reaction mixture was stirred for 2.5 hours and then 5-[4-(4-oxo-piperidin-1-yl)-benzyl]-thiazolidine-2,4-dione (which was obtained in Example 38) (0.116 mg, 0.38 mmol), sodium triacetoxyborohydride (0.212 g, 1.0 mmol), and acetic acid (0.2 mL) were added. After stirring for 1.5 hours aqueous sodium bicarbonate solution was added and the resulting solid was collected. The product was purified by flash silica gel chromatography eluting with methylene chloride and methanol to give the title compound as a pale grey solid; mp>105° C. (decomposed); 1H NMR (300 MHz, DMSO-d6) δ 1.30–1.50(m, 2 H), 1.80–2.00(m, 2 H), 2.60–3.60(m, 9 H), 3.00(s, 3 H), 4.40–4.55(m, 1 H), 4.65–4.75(m, 1 H), 6.84(d, J=8.4 Hz, 2 H), 7.04(d, J=8.4 Hz, 1 H), 7.20(d, J=8.1 Hz, 1 H), 7.40–7.50(m, 2 H); MS (ES) m/z: 553.2 (MH+, 100%); HRMS Calcd. for C24H30ClN4O5S2 (MH+): 553.1440. Found: 553.1336.
