N-[3-chloro-4-(pyridin-2-ylmethoxy)phenyl]-5,8-dihydro-6H-spiro[1-benzothieno[2,3-d]pyrimidine-7,2'-[1,3]dioxolan]-4-amine hydrochloride → 4-{[3-chloro-4-(pyridin-2-ylmethoxy)phenyl]amino}-5,8-dihydro[1]benzothieno[2,3-d]pyrimidin-7(6H)-one hydrochloride

To a stirring acetic acid/H2O solution (4:1, 250 mL) was added N-[3-chloro-4-(pyridin-2-ylmethoxy)phenyl]-5,8-dihydro-6H-spiro[1-benzothieno[2,3-d]pyrimidine-7,2′-[1,3]dioxolan]-4-amine hydrochloride (10.0 g, 19.3 mmol), and the contents heated at 80° C. for 40 h. The dark colored mixture was cooled to rt, and the solvent removed under reduced pressure. The crude residue was suspended in water (200 mL), stirred for 10 min., and filtered. The collected solid was further washed with H2O (300 mL) and ether (100 mL) to afford the desired product as a brown solid (8.1 g, 89%). 1H-NMR (DMSO-d6) δ 8.71 (d, 1H), 8.54 (s, 1H), 8.42 (s, 1H), 8.10 (td, 1H), 7.78 (d, 1H), 7.75 (d, 1H), 7.56 (m, 2H), 7.25 (d, 1H), 5.38 (s, 2H), 5.08 (br, 1H), 3.76 (s, 2H), 3.50 (t, 2H), 2.69 (t, 2H); LCMS RT=2.44 min; [M+H]+=437.3.