Reaction Steps
The procedure used for the preparation of 9a was repeated with 8m (157 mg, 0.240 mmol), Et3SiH (0.383 mL, 2.40 mmol), and trifluoroacetic acid (0.739 mL, 9.59 mmol) in dry ClCH2CH2Cl (6 mL) at 0° C. under nitrogen to give 9m (113 mg, 96%) as a white solid after crystallization from THF/CH2Cl2 /hexane. mp 140° C. (dec); IR (KBr) 3600-2650 (br), 3286, 1782, 1738, 1671, 1230 cm-1 ; 1H NMR (DMSO-d6) δ1.98 (3H, s, CH3), 3.44 (1H, d, J=18.1 Hz), 3.59 (1H, d, J=18.1 Hz), 3.72 (2H, s, CH2), 4.64 (1H, d, J=12.8 Hz), 4.96 (1H, d, J=12.8 Hz), 5.07 (1H, d, J=4.8 Hz), 5.69 (1H, dd, J=8.2 and 4.8 Hz), 6.82 (1H, d, J=7.8 Hz), 7.22 (1H, t, J=7.8 Hz), 7.28 (1H, d, J=7.8 Hz), 7.29 (1H, s), 7.39 (1H, s), 9.06 (1H, d, J=8.2 Hz, NH), 9.68 (1H, br s, OH), 13.62 (1H, br s, CO2H); FDMS m/z 490 (M+ +1); Anal. Calcd for C21H19N3O7S2.(C4H8O) 0.25: C, 52.06; H, 4.17; N, 8.28. Found: C, 51.95; H, 3.94; N, 8.04
