[NH2:1][C:2]1[S:6][C:5]2[CH2:7][CH2:8][CH2:9][CH2:10][C:4]=2[C:3]=1[C:11]([O:13]CC)=O.[CH2:16]([O:18][C:19](=[O:23])[CH2:20][C:21]#[N:22])[CH3:17].C([O-])(O)=O.[Na+]>O1CCOCC1>[OH:13][C:11]1[C:3]2[C:4]3[CH2:10][CH2:9][CH2:8][CH2:7][C:5]=3[S:6][C:2]=2[N:1]=[C:21]([CH2:20][C:19]([O:18][CH2:16][CH3:17])=[O:23])[N:22]=1The ethyl 2-amino-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxylate (8.0 g, 0.0355 mol) and ethyl-2-cyanoacetate (8.03 g, 0.0710 mol) was dissolved in dioxane (250 ml). It was cooled to 0° C. To this reaction mixture, HCl gas was purged up to saturation (for 20 min, initially reaction mass becomes turbid and then becomes clears). Then reaction mass was stirred for 18 h at room temperature. After completion of the reaction it was cooled to 0° C. and basified with saturated NaHCO3 (pH=8). Further it was extracted with ethyl acetate (250 ml×3). Combined organic extracts were washed with water followed with brine. Separated organic layer was dried over anhy. Na2SO4, filtered and concentrated to get 9 g crude product. It was purified by column chromatography by using 100-200 mesh silica gel and 1-2% MeOH: DCM solvent system to give ethyl 2-(4-hydroxy-5,6,7,8-tetrahydrobenzo[4,5]thieno[2,3-d]pyrimidin-2-yl)acetate as yellow solid. Yield—(9.0 g, 86.71%); 1H-NMR: (400 MHz, CDCl3); δ=4.25-4.20 (q, 2H), 3.77 (s, 2H), 3.00-2.97 (m, 2H), 2.76-2.74 (m, 2H), 1.88-1.81 (m, 4H), 1.29-1.25 (t, 3H); LC-MS [M+H]=292.9.
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