Reaction Steps
The procedure used for the preparation of 9a was repeated with 8o (193 mg, 0.288 mmol), Et3SiH (0.461 mL, 2.88 mmol), and trifluoroacetic acid (0.887 mL, 11.5 mmol) in dry ClCH2CH2Cl (7 mL) at 0° C. under nitrogen to give 9o (106 mg, 73%) as a white solid after crystallization from THF/CH2Cl2 /hexane. mp 178° C. (dec); IR (KBr) 3550-2800 (br), 3278, 1785, 1735, 1667, 1256 cm-1 ; 1H NMR (DMSO-d6) δ1.98 (3H, s, CH3), 3.45 (1H, d, J=18.1 Hz), 3.59 (1H, d, J=18.1 Hz), 3.74 (2H, s, CH2), 3.96 (3H, s, CH3), 4.65 (1H, d, J=12.8 Hz), 4.96 (1H, d, J=12.8 Hz), 5.07 (1H, d, J=4.8 Hz), 5.71 (1H, dd, J=8.1 and 4.8 Hz), 7.04 (1H, t, J=7.5 Hz), 7.19 (1H, d, J=8.3 Hz), 7.37-7.42 (1H, m), 7.41 (1H, s), 8.22 (1H, d, J=7.5 Hz), 9.06 (1H, d, J=8.1 Hz, NH), 13.62 (1H, br s, CO2H); FDMS m/z 504 (M+ +1); Anal. Calcd for C22H21N3O7S2 : C, 52.48; H, 4.20; N, 8.34. Found: C, 52.72; H, 4.27; N, 8.10
