[CH2:1]([O:3][C:4](=[O:18])[CH2:5][C:6]1[N:7]=[C:8]([C:11]2[CH:16]=[CH:15][CH:14]=[CH:13][C:12]=2[OH:17])[S:9][CH:10]=1)[CH3:2].[OH:19]C1C=CC=C(O)C=1C(=S)N.ClCC(=O)CC(OCC)=O.[Li+].[Br-]>C1COCC1>[CH2:1]([O:3][C:4](=[O:18])[CH2:5][C:6]1[N:7]=[C:8]([C:11]2[C:16]([OH:19])=[CH:15][CH:14]=[CH:13][C:12]=2[OH:17])[S:9][CH:10]=1)[CH3:2]The procedure used for the preparation of 4a was repeated with 2,6-dihydroxybenzenecarbothioamide 3b (1.02 g, 6.04 mmol), ethyl 4-chloroacetoacetate (1.99 g, 12.1 mmol), and LiBr (525 mg, 6.04 mmol) in dry THF (15 mL) to give 4b (1.16 g, 69%) as a white solid after chromatographic purification on silica gel (gradient EtOAc/CH2Cl2 : 0-12%) and recrystallization from EtOAc/hexane. mp 152.5°-154.0° C.; IR (KBr) 3256 (br), 1742, 1460, 1157 cm-1 ; 1H NMR (DMSO-d6) δ1.17 (3H, t, J=7.2 Hz, CH3), 3.88 (2H, s, CH2), 4.08 (2H, q, J=7.2 Hz, CH2), 6.44 (2H, d, J=8.2 Hz, Ar), 7.09 (1H, t, J=8.2 Hz, Ar), 7.51 (1H, s), 12.19 (2H, s, OH); FDMS m/z 279 (M+); Anal. Calcd for C13H13NO4S: C, 55.90; H, 4.69; N, 5.01. Found: C, 56.19; H, 4.85; N, 4.86.
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