to 10 u00b0 c with stirring filtered the product and washed with precooled cyclohexane to obtain 98 5 g of 4 benzyl 1 methyl 2 oxo 3 phenylpiperazine product yield 93 8 purity 99 15 by hplc 0024 1 h nmr 300 mhz in cdcl 3 u03b4 ppm 2 49 2 57 m 1h 2 97 s 3h 2 99 3 03 m 1h 3 14 3 18 m 2h 3 54 3 77 m 2h 4 06 s 1h 7 21 7 53 m 10h 14 62 g of lithium aluminium hydride 0 385 moles was suspended in 450 ml of tetrahydrofuran at 15 u00b0 c under nitrogen atmosphere 90 g of 4 benzyl 1 methyl 2 oxo 3 phenylpiperazine 0 321 moles was added slowly in 1 hour at 10 15 u00b0 c the reaction mass was refluxed for 6 hours thereafter the reaction mass was cooled to 5 u00b0 c and quenched successively with 15 ml of water 15 ml of 15 aqueous sodium hydroxide solution 45 ml of water the reaction mass was stirred for 1 hour at 20 25 u00b0 c filtered and residue was washed with tetrahydrofuran 2 u00d7 90 ml the filtrate was concentrated and 300 ml of water was added filtered the product washed with water and dried under reduced pressure to obtain 80 g of the title compound yield 93 6 0026 1 h nmr 300 mhz in cdcl 3 u03b4 ppm 2 08 2.