Hydrochloric Acid → 3-(1H-pyrazol-5-yl)piperidine

A 250-mL round-bottom flask was charged with a solution of benzyl 3-(1H-pyrazol-5-yl)piperidine-1-carboxylate (14 g, 46.61 mmol, 1.00 equiv, 95%) in dioxane (100 mL). To the mixture was added conc.HCl (60 mL, 36%). The resulting mixture was refluxed for 2 hours. The progress was monitored by TLC (DCM:MeOH=10:1). Upon completion, the resulting mixture was concentrated on a rotary evaporator. Then, pH was adjusted to 9 with saturated aqueous Na2CO3. The resulting mixture was then extracted with THF (8×200 mL). Combined organic layers were dried over anhydrous magnesium sulfate. After filtration and concentration on a rotary evaporator, the residue was purified by a silica gel column chromatography eluted with EtOAc/MeOH (10:1) affording 3-(1H-pyrazol-5-yl)piperidine as pale yellow oil (4 g, 54%). LCMS: [M+H]+: 152.1; 1H NMR (CDCl3) δ 7.47 (s, 1H), 6.05 (s, 1H), 3.16 (m, 1H), 3.11 (m, 2H), 2.99 (m, 1H), 2.76 (m, 1H), 2.57 (m, 2H), 1.95 (m, 1H), 1.56 (m, 1H), 1.46 (m, 2H).

1. additionTo the mixture was added conc
2. temperatureThe resulting mixture was refluxed for 2 hours
3. concentrationUpon completion, the resulting mixture was concentrated on a rotary evaporator
4. extractionThe resulting mixture was then extracted with THF (8×200 mL)
5. dry with materialCombined organic layers were dried over anhydrous magnesium sulfate
6. filtrationAfter filtration and concentration
7. customon a rotary evaporator
8. customthe residue was purified by a silica gel column chromatography
9. washeluted with EtOAc/MeOH (10:1)

ORD record

ord-8d027304233b4ace837f4583862f21d6

Source dataset

uspto-grants-2011_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08080566B1