Methylboronic Acid → 4-(3,5-Dimethylpyridin-2-yl)piperazine-1-carboxylic acid tert-butyl ester

HRID 1803981Notes

Reaction equation

HRID 1803981 reaction equation
[C:1]([O:5][C:6]([N:8]1[CH2:13][CH2:12][N:11]([C:14]2C(Cl)=CC(Cl)=C[N:15]=2)[CH2:10][CH2:9]1)=[O:7])([CH3:4])([CH3:3])[CH3:2].C1(P(C2CCCCC2)C2C=CC=C[C:30]=2[C:35]2[C:40](OC)=C[CH:38]=[CH:37][C:36]=2OC)CCCCC1.[F-].[K+].CB(O)O>C([O-])(=O)C.[Pd+2].C([O-])(=O)C.O.O1CCCC1>[C:1]([O:5][C:6]([N:8]1[CH2:9][CH2:10][N:11]([C:14]2[C:37]([CH3:38])=[CH:36][C:35]([CH3:30])=[CH:40][N:15]=2)[CH2:12][CH2:13]1)=[O:7])([CH3:4])([CH3:2])[CH3:3]

Participants

8

Reactant 4

HCID 139377Methylboronic AcidHCID 522689Potassium FluorideHCID 112698722-Dicyclohexylphosphino-2',6'-dimethoxybiphenylHCID 67380983Tert-butyl 4-(3,5-dichloropyridin-2-yl)piperazine-1-carboxylate

Product 1

HCID 673812824-(3,5-Dimethylpyridin-2-yl)piperazine-1-carboxylic acid tert-butyl esterYield 449%

Reagents, catalysts & solvents 3

HCID 167845palladium(II) acetateCatalystHCID 962WaterSolventHCID 8028TetrahydrofuranSolvent

Procedure

To 2,3,5-trichloropyridine (25 g) were added 1-BOC-piperazine (28.13 g), potassium carbonate (37.86 g), N,N-dimethylformamide (25 mL) and toluene (50 mL), and the mixture was stirred at 100° C. After completion of the reaction, water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer was washed with saturated brine, and the solvent was evaporated. The residue was purified by column chromatography (hexane:ethyl acetate) to give 4-(3,5-dichloropyridin-2-yl)piperazine-1-carboxylic acid tert-butyl ester (39.13 g). To 4-(3,5-dichloropyridin-2-yl)piperazine-1-carboxylic acid tert-butyl ester (6.35 g) were added palladium (II) acetate (0.46 g), 2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl (1.71 g), potassium fluoride (9.556 g), methylboronic acid (5 g) and tetrahydrofuran (202 mL), and the mixture was refluxed under a nitrogen stream for 8 hr. Water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer was washed with saturated brine, and the solvent was evaporated. The residue was purified by column chromatography (hexane:ethyl acetate) to give 4-(3,5-dimethylpyridin-2-yl)piperazine-1-carboxylic acid tert-butyl ester (5.45 g). To 4-(3,5-dimethylpyridin-2-yl)piperazine-1-carboxylic acid tert-butyl ester (5.45 g) were added 4N hydrogen chloride/ethyl acetate (18.2 mL) and chloroform (45.5 mL), and the mixture was stirred at room temperature. After completion of the reaction, to the reaction mixture were added water and potassium carbonate, and the mixture was extracted with ethyl acetate. The solvent was evaporated to give the title compound (3.3 g).

Workup

  1. temperaturethe mixture was refluxed under a nitrogen stream for 8 hr
  2. extractionthe mixture was extracted with ethyl acetate
  3. washThe organic layer was washed with saturated brine
  4. customthe solvent was evaporated
  5. customThe residue was purified by column chromatography (hexane:ethyl acetate)

Sources & evidence

ORD record
ord-1737e21a54b9438db0d2c1f6f66a1f40
Source dataset
uspto-grants-2013_01
Patent number
US08354401B2

Reaction notes

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