C([Li])CCC.[F:6][C:7]1[C:12]([F:13])=[CH:11][CH:10]=[CH:9][C:8]=1[CH2:14][S:15][C:16]1[N:21]=[C:20]([NH2:22])[C:19]([N:23]=O)=[C:18]([NH2:25])[N:17]=1.[O:26]1CC[CH2:28][CH2:27]1>CN(C)C=O>[NH2:25][C:18]1[C:19]2[N:23]=[CH:28][C:27](=[O:26])[NH:22][C:20]=2[N:21]=[C:16]([S:15][CH2:14][C:8]2[CH:9]=[CH:10][CH:11]=[C:12]([F:13])[C:7]=2[F:6])[N:17]=1To a solution of triethyl phosphonoacetate (15.0 g) in tetrahydrofuran (60 ml) cooled in an ice bath was added butyllithium (2.5 M in hexanes, 25.6 ml) at a rate such that the internal temperature was maintained below 30° C. To this mixture was then added a solution of the product of Example 2 step (b) (10.0 g) in N,N-dimethylformamide (60 ml). The reaction mixture was heated at reflux for 1 hour, then cooled to room temperature and quenched with acetic acid (6 ml). The solid thus precipitated was isolated by filtration, washed with water, ethanol and diethyl ether, and dried over P2O5 at 50° C. to give the sub-titled product as a pale green solid (9.3 g).
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