Phosphorus oxychloride → 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 0° C. POCl3 (200 mL) 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) was added triethylamine (200 mL) from a dropping funnel over a 15 min. period. The contents 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 rt. The heterogeneous mixture was concentrated under reduced pressure, the residue diluted with ethyl acetate (100 mL), and again concentrated. The residue was diluted with ethyl acetate (100 mL) and the heterogeneous mixture poured onto a stirring mixture of ice-water/sq. NaHCO3 (800 mL). After 5 min. stirring, the now pH=7 contents 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