Acetic Anhydride → (5R)-4-chloro-5-methyl-6,7-dihydro-5H-cyclopenta[d]pyrimidin-7-yl acetate

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Reaction Steps

A solution of (R)-4-chloro-5-methyl-6,7-dihydro-5H-cyclopenta[d]pyrimidine-oxide (1.45 g, 7.85 mmol) in acetic anhydride (20 mL) was heated to 110° C. for 2 hours. After cooling, excess solvent was removed under vacuum. The residue was purified by silica gel chromatography, eluting with hexane/ethyl acetate (3:1) to give (5R)-4-chloro-5-methyl-6,7-dihydro-5H-cyclopenta[d]pyrimidin-7-yl acetate (1.25 g, 70%). 1H NMR (CDCl3, 400 MHz) δ 8.92 (m, 1H), 6.30-6.03 (m, 1H), 3.60-3.30 (m, 1H), 2.84 (m, 1H), 2.40-2.20 (m, 1H), 2.15 (d, J=6 Hz, 2H), 1.75 (m, 2H), 1.47 (d, J=6.8, 2H), 1.38 (d, J=7.2, 1H). MS (APCI+) [M+H]+ 227.

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