1-cyclopentylimidazolidin-2-one

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A −20° C. solution of 1-(2-chloroethyl)-3-cyclopentylurea (8.5 g, 44.6 mmol) in THF (446 mL), under Ar, was treated with NaH (60% in mineral oil, 4.46 g, 111 mmol), stirred at −10° C. for 1 h, 0° C. for 1 h, then RT for 3 h. The mixture was cooled to 0° C., treated with 50% satd. NH4Cl, the layers separated and the aqueous layer extracted with EtOAc (3×). The combined organics were dried over Na2SO4 and concentrated to dryness. The material was suspended in Et2O, the solids removed via filtration and the filtrate concentrated to dryness. The resulting material was dissolved in DCM, treated drop-wise with hexane until solids formed and the solids were collected via filtration and dried to afford 1-cyclopentylimidazolidin-2-one (4.3 g, 63%) as a white solid. 1H NMR (400 MHz, DMSO-d6): δ 6.16 (s, 1 H), 4.07-3.98 (m, 1 H), 3.28-3.22 (m, 2 H), 3.19-3.14 (m, 2 H), 1.66-1.55 (m, 4 H), 1.52-1.41 (m, 4 H); MS (ESI) m/z: 155.1 (M+H+). RT for 3 h The mixture was cooled to 0° C. treated with 50% NH4Cl, the layers separated the aqueous layer extracted with EtOAc (3×) The combined organics were dried over Na2SO4 concentrated to dryness the solids removed via filtration the filtrate concentrated to dryness The resulting material was dissolved in DCM treated drop-wise with hexane until solids formed the solids were collected via filtration dried