To a slurry of N-[4-[4-(4-methoxyphenyl)-1-piperazinyl]-phenyl]-N′-2-methylethyl-N′-[2-hydroxyethyl]urea (Formula Va, 35.0 mmol, 14.4 g) in tetrahydrofuran (600 mL) was added potassium tert-butoxide (123.0 mmol, 11.2 g). The reaction vessel was cooled in an ice bath and a tetrahydrofuran (200 mL) solution of p-toluenesulfonyl chloride (57.0 mmol, 10.9 g) was added over a period of 0.5 hours. The resulting beige mixture was allowed to stir at ambient temperature for 14 hours before addition of water (200 mL). The mixture was filtered and the product was washed with water (200 mL) and dried. A white powder of 1-[4-[4-(4-methoxyphenyl)-1-piperazinyl]phenyl]-3-(1-methylethyl)-2-oxoimidazolidine (10.6 g) was obtained in 77% overall yield from 4-[4-(4-methoxyphenyl)-1-piperazinyl]benzenamine. 1H NMR (400 MHz, CDCl3) δ 7.46 (d, J=9.2 Hz, 2 H, Ar), 6.96 (d, J=9.2 Hz, 2 H, Ar), 6.95 (d, J=9.2 Hz, 2 H, Ar), 6.86 (d, J=9.2 Hz, 2 H, Ar), 4.30-4.20 (m, 1 H, CH), 3.76 (s, 3 H, OCH3), 3.82-3.72 (m, 2 H, CH2), 3.45-3.38 (m, 2 H, CH2), 3.32-3.20 (m, 8 H, CH2). The product was shown by HPLC retention time and NMR spectroscopy to be identical to an authentic standard prepared by the literature procedure. More importantly, the product of the present invention was demonstrated by HPLC to be purer (99.97 area %) relative to that of material prepared by the literature procedure (99.39 area %). Furthermore the product of the present invention did not contain the impurity which may negatively impact the quality of Pramiconazole, and which was present in material prepared by the literature procedure.
