Dabco → 4-(3-Fluoro-benzyl)-5-oxo-7-[4-(thiophene-2-carbonyl)-piperazin-1-yl]-4,5-dihydro-thieno[3,2-b]pyridine-6-carboxylic acid ethyl ester

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A solution of 7-chloro-4-(3-fluoro-benzyl)-5-oxo-4,5-dihydro-thieno[3,2-b]pyridine-6-carboxylic acid ethyl ester (17) (45 g, 123 mmol), 1,4-diazabicyclo[2.2.2]octane (15.9 g, 141 mmol) and piperazin-1-yl-thiophene-2-yl-methanone (27.8 g, 141 mmol) in dry DMF was heated at 110° C. for 7 h under argon. The solution was cooled and poured into 2% ammonium chloride solution. The solids formed were filtered and washed by cold water. The solids were dissolved in dichloromethane and washed by water. The organic phase was dried over MgSO4 and concentrated under vacuum to yield 58.6 g (91%) of 4-(3-fluoro-benzyl)-5-oxo-7-[4-(thiophene-2-carbonyl)-piperazin-1-yl]-4,5-dihydro-thieno[3,2-b]pyridine-6-carboxylic acid ethyl ester. 1H-NMR (DMSO-d6): δ 1.29 (t, J=7.2 Hz, 3H), 3.37 (m, 4H), 3.82 (m, 4H), 4.27 (q, J=7.2 Hz, 2H), 5.38 (s, 2H), 7.05-7.16 (m, 4H), 7.33 (d, J=5.6 Hz, 1H), 7.36 (m, 1H), 7.48 (dd, J=1.2, 3.6 Hz, 1H), 7.79 (dd, J=1.2, 5.2 Hz, 1H), 8.03 (d, J=5.6 Hz, 1H); EIMS m/z 526 (M+1). Anal. (C26H24FN3O4S2) C, H, N.

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