Experimental section
General
Melting points were determined on a Boetius melting point apparatus and …show more content…
Then, p-nitrobenzeneazide (0.16 g, 1.0 mmol) was added. The mixture was stirred at room temperature until complete consumption of the starting materials, monitored by TLC. The reaction mixture was diluted with 25 mL of water, cooled in ice, and extracted with CH2Cl2 (3x15 mL). The combined organic extracts were washed with brine, and dried (MgSO4). After removal of the solvent under reduced pressure, the residue was purified on silica gel with n-hexane–ethylacetate (8:2) yielding the target compound 8 as colorless powder (0.42 g, 79%); mp: 182-183 …show more content…
9.76 (s, 1H, NH), 10.35 (s, 1H, NH), 12.34 (s, 1H, NH); 13C-NMR (100 MHz, DMSO-d6): δ 13.8 (CH3), 14.4 (CH3), 14.5 (CH3), 25.8 (C-4), ¬41.0 (C-5), 42.1 (C-7), 60.5 (CH2, ester), 60.8 (CH2, carbamate), 61.2 (CH2, carbamate), 111.5 (C-3), 122.5 (C-3a), 128.9 (C-7a), 149.5 (C-2), 154.5 (C=O), 155.6 (C=O, carbamate), 165.1 (C=O, carbamate), 176.7 (C=S). (EI-MS): m/z calcd.. C17H24N4O6S2 [M]+: 444,11 found: