m-Chloroperbenzoic acid → 4-chloro-6,7-dihydro-5H-cyclopenta[d]pyrimidine 1-oxide

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Reaction Steps

To a solution of 4-chloro-6,7-dihydro-5H-cyclopenta[d]pyrimidine (5.69 g, 36.8 mmol) in chloroform (200 mL) was added MCPBA (19 g, 84.8 mmol) in chloroform (50 mL) dropwise. The mixture was stirred at room temperature for 16 hour. After cooling with ice-water, the mixture was quenched with Na2S2O3 (27.5 g) in water (110 mL) dropwise and followed by Na2CO3 (14 g) in water (52 mL) dropwise. The organic phase was separated and the aqueous phase was extracted with chloroform (3×200 mL). The organic phase was dried and concentrated at low temperature (<25° C.). The residue was subject to chromatography on silica gel, eluting by ethyl acetate to afford 4-chloro-6,7-dihydro-5H-cyclopenta[d]pyrimidine 1-oxide (2.93 g, 47%). MS (APCI+) [M+H] +171.

Provenance & Evidence