Triethylamine → 4-chloro-5,8-dihydro-6H-spiro[1-benzothieno[2,3-d]pyrimidine-7,2'-[1,3]dioxolane]

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Reaction Steps

To a stirring solution of 3,5,6,8-tetrahydro-4H-spiro[1-benzothieno[2,3-d]pyrimidine-7,2′-[1,3]dioxolan]-4-one (20.0 g, 0.076 mol) in POCl3 (200 mL) at 0° C. was added triethylamine (200 mL) over a 15 min. period. The resulting mixtures were allowed to warm to rt, and then heated to 80° C. After 3 h, the contents were removed from heating, and allowed to cool to it. The heterogeneous mixture was concentrated under reduced pressure. The residue was diluted with EtOAc (100 mL), and concentrated again to further remove the volatile materials. The residue was then diluted with EtOAc (100 mL) and the heterogeneous mixture poured onto a stirring mixture of ice-water/aq NaHCO3 (800 mL). After 5 min. stirring, the contents (pH≈7) were filtered and the solid filter cake washed with water. The product was dried in vacuum oven overnight to afford the desired product (20.7 g, 97%) as an off-white solid. 1H-NMR (DMSO-d6) δ 8.82 (s, 1H), 3.97 (s, 4H), 3.10 (t, 2H), 3.07 (s, 2H), 1.95 (t, 2H); LCMS RT=2.45 min; [M+H]+=283.1.

Provenance & Evidence