The procedure used for the preparation of 9a was repeated with 8n (152 mg, 0.261 mmol), Et3SiH (0.417 mL, 2.61 mmol), and trifluoroacetic acid (0.804 mL, 10.4 mmol) in dry ClCH2CH2Cl (4 mL) at 0° C. under nitrogen to give 9n (108 mg, 99%) as a white solid after crystallization from THF/Et2O/hexane. mp 195° C. (dec); IR (KBr) 3600-2600 (br), 3343, 1787, 1682, 1532 cm-1 ; 1H NMR (DMSO-d6) δ3.49 (1H, dd, J=19.0 and 6.0 Hz), 3.59 (1H, dd, J=19.0 and 2.6 Hz ), 3.73 (2H, s, CH2), 5.01 (1H, d, J=4.9 Hz), 5.73 (1H, dd, J=8.3 and 4.9 Hz), 6.45 (1H, dd, J=6.0 and 2.6 Hz), 6.88 (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), 7.38 (1H, s), 9.05 (1H, d, J=8.3 Hz, NH), 9.68 (1H, s, OH), 13.15 (1H, br s, CO2H); FDMS m/z 417 (M+), 418 (M+ +1); Anal. Calcd for C18H15N3O5S2 : C, 51.79; H, 3.62; N, 10.07. Found: C, 51.95; H, 3.66; N, 9.80
