Methanol → 1-(3,4-Dinitrobenzyl)-4-methylpiperazine

To a cooled solution (−5° C.) of (3,4-dinitrophenyl)-(4-methylpiperazin-1-yl)methanone (5.88 g, 20 mmol) in THF, was added powdered NaBH4 (1.89 g, 50 mmol), followed by the dropwise addition of BF3.OEt2 (6.4 mL, 50 mmol), while keeping the temperature below 5° C. The mixture was allowed to come to room temperature over 2 hrs, and then stirred for a further 3 hrs at room temperature. MeOH was then added cautiously to the mixture, the stirring was continued for 10 minutes and then the mixture was concentrated. The residue was partitioned between EtOAc (150 mL) and saturated aqueous NaHCO3 (150 mL). The organic layer was washed with water (100 mL), brine (100 mL) and then dried by Na2SO4, filtered and concentrated. The residue was purified by silica gel chromatography (eluent: 2% MeOH in CH2Cl2) to give a yellow solid (4.5 g, 80.3%). 1H NMR (300 MHz, CDCl3) δ: 7.90-7.92 (1 H, d, J=6.0 Hz), 7.90 (1 H, s), 7.69-7.71 (1 H, d, J=6.0 Hz), 3.73 (2 H, s), 3.07-3.10 (2 H, m), 2.94-2.99 (2 H, m), 2.76-2.81 (2 H, m), 2.67 (3 H, s), 2.53-2.56 (2 H, m).

1. customthe temperature below 5° C
2. waitthe stirring was continued for 10 minutes
3. concentrationthe mixture was concentrated
4. customThe residue was partitioned between EtOAc (150 mL) and saturated aqueous NaHCO3 (150 mL)
5. washThe organic layer was washed with water (100 mL), brine (100 mL)
6. dry with materialdried by Na2SO4
7. filtrationfiltered
8. concentrationconcentrated
9. customThe residue was purified by silica gel chromatography (eluent: 2% MeOH in CH2Cl2)

ORD record

ord-8fa3544d87d4482f89f6ae8e7e3504da

Source dataset

uspto-grants-2015_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09174996B2