tert-Butylhydrazine monohydrochloride → 1-Tert-butoxycarbonyl-4-(1-tert-butyl-3-methyl-5-pyrazolyl)piperazine

1-Acetoacetyl-4-tert-butoxycarbonylpiperazine [product of Example 222 (1), 3.92 g] was dissolved in ethanol (300 mL), and tert-butylhydrazine hydrochloride (1.81 g) and molecular sieves 3A (10 g) were added thereto at room temperature. The mixture was stirred for 15 hr. The reaction mixture was filtrated and the filtrate was concentrated under reduced pressure. The residue was dissolved in pyridine (200 mL), and phosphorus oxychloride (3.0 mL) was added thereto at room temperature. The mixture was stirred for 24 hr. The reaction mixture was concentrated under reduced pressure, the residue was acidified with dilute hydrochloric acid to pH 3. The mixture was extracted with ethyl acetate. The extract was washed successively with saturated aqueous sodium hydrogencarbonate solution and brine and dried. The solvent was evaporated under reduced pressure and the residue was purified by silica gel chromatography to give 1-tert-butoxycarbonyl-4-(1-tert-butyl-3-methyl-5-pyrazolyl)piperazine (886 mg) as an oil.

1. customat room temperature
2. filtrationThe reaction mixture was filtrated
3. concentrationthe filtrate was concentrated under reduced pressure
4. dissolutionThe residue was dissolved in pyridine (200 mL)
5. additionphosphorus oxychloride (3.0 mL) was added
6. customat room temperature
7. stirringThe mixture was stirred for 24 hr
8. concentrationThe reaction mixture was concentrated under reduced pressure
9. extractionThe mixture was extracted with ethyl acetate
10. washThe extract was washed successively with saturated aqueous sodium hydrogencarbonate solution and brine
11. customdried
12. customThe solvent was evaporated under reduced pressure
13. customthe residue was purified by silica gel chromatography

ORD record

ord-fff3605f9f014a9eafe9279be4b48ca9

Source dataset

uspto-grants-2006_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07074794B2