tert-Butyl piperazine-1-carboxylate → HCID 59252248, compound

Temperature

85 °C

To a stirring solution of 2-chloro-4-bromopyridine (4.3 g, 22.5 mmol) in toluene (100 mL) was added piperazine-1-carboxylic acid tert-butyl ester (3.2 g, 17.2 mmol) and sodium tert-butoxide (2.5 g, 26.0 mmol). The flask was evacuated and flushed with N2(g) twice. A mixture of Xantphos (600 mg, 1.0 mmol) and Pd2(dba)3 (318 mg, 0.35 mmol) was added in one portion and the mixture was heated at 85° C. for 20 h. The mixture was cooled to rt, diluted with H2O (75 mL), and extracted with EtOAc (3×). The combined organic layers were dried and concentrated to give a clear golden oil. The oil was purified on FCC (0 to 5% 2 M NH3 in MeOH/CH2Cl2) to give the title product as a beige solid (5.1 g, 100%). MS (ESI): mass calcd. for C14H20ClN3O2, 297.1; m/z found, 298.2 [M+H]+. 1H NMR (DMSO-d6): 7.95 (d, J=5.9, 1H), 6.88-6.78 (m, 2H), 3.46-3.32 (m, 8H), 1.42 (s, 9H). tert-Butyl 4-[2-(cyclopentylamino)pyridin-4-yl]piperazine-1-carboxylate. To a stirring solution of 4-(2-chloro-pyridin-4-yl)-piperazine-1-carboxylic acid tert-butyl ester (163 mg, 0.55 mmol) in toluene (2 mL) in a vial was added cyclopentylamine (136 μL, 1.38 mmol) and sodium tert-butoxide (161 mg, 1.68 mmol). A mixture of racemic BINAP (20 mg, 0.032 mmol) and Pd(OAc)2 (18 mg, 0.027 mmol) was added in one portion and the mixture was heated at 85° C. for 20 h. The mixture was cooled to rt and purified directly by FCC (0 to 5% 2 M NH3 in MeOH/CH2Cl2) to provide the title compound as a white solid (34 mg, 17%). MS (ESI): mass calcd. for C16H30N4O2, 346.2; m/z found, 347.3 [M+H]+. 1H NMR (DMSO-d6): 7.65 (d, J=6.0, 1H), 6.10 (d, J=6.0, 1H), 5.92 (d, J=7.1, 1H), 5.78 (s, 1H) 4.08-4.02 (m, 1H), 3.41 (t, J=5.4, 4H), 3.16 (t, J=5.4, 4H), 1.89-1.82 (m, 2H), 1.67-1.61 (m, 2H), 1.59-1.48 (m, 2H), 1.42 (s, 9H), 1.43-1.35 (m, 2H). N-Cyclopentyl-4-piperazin-1-ylpyridin-2-amine dihydrochloride. To a stirring solution of tert-butyl 4-[2-(cyclopentylamino)pyridin-4-yl]piperazine-1-carboxylate (34 mg, 0.1 mmol) in 96% formic acid (4 mL) was added 6 N aq HCl (2 drops). The mixture was stirred for 2 h and concentrated to give the desired product as a white solid (26 mg, 93%). MS (ESI): mass calcd. for C14H22N4, 246.2; m/z found, 247.2 [M+H]+. 1H NMR (DMSO-d6): 9.32 (s, 2H), 7.89 (d, J=7.1, 1H), 7.69 (d, J=7.5, 1H), 6.58 (d, J=7.6, 1H), 6.04 (s, 1H), 4.03-3.96 (m, 1H), 3.73 (t, J=4.9, 4H), 3.20 (t, J=5.0, 4H), 2.03-1.95 (m, 2H), 1.73-1.68 (m, 2H), 1.64-1.52 (m, 2H), 1.50-1.42 (M, 2H). The compounds in Example 17 through Example 20 were prepared using methods analogous to those described for Example 16.

1. customThe flask was evacuated
2. customflushed with N2(g) twice
3. additionwas added in one portion
4. temperatureThe mixture was cooled to rt
5. extractionextracted with EtOAc (3×)
6. customThe combined organic layers were dried
7. concentrationconcentrated
8. customto give a clear golden oil
9. customThe oil was purified on FCC (0 to 5% 2 M NH3 in MeOH/CH2Cl2)

ORD record

ord-59a954b86b884cba903af354b07c869a

Source dataset

uspto-grants-2014_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08841287B2