Toluene → 4-(3-Methyl-5-vinylpyridin-2-yl)piperazine-1-carboxylic acid tert-butyl ester

HRID 2411206Notes

Reaction equation

HRID 2411206 reaction equation
[C:1]([O:5][C:6]([N:8]1[CH2:13][CH2:12][N:11]([C:14]2[C:19]([CH3:20])=[CH:18][C:17](Br)=[CH:16][N:15]=2)[CH2:10][CH2:9]1)=[O:7])([CH3:4])([CH3:3])[CH3:2].P([O-])([O-])([O-])=O.[K+].[K+].[K+].[CH:30](B1OC(C)(C)C(C)(C)O1)=[CH2:31].C1(C)C=CC=CC=1>C1CCC(P(C2CCCCC2)C2CCCCC2)CC1.C1CCC(P(C2CCCCC2)C2CCCCC2)CC1.[Cl-].[Cl-].[Pd+2].O>[C:1]([O:5][C:6]([N:8]1[CH2:13][CH2:12][N:11]([C:14]2[C:19]([CH3:20])=[CH:18][C:17]([CH:30]=[CH2:31])=[CH:16][N:15]=2)[CH2:10][CH2:9]1)=[O:7])([CH3:4])([CH3:3])[CH3:2]

Participants

7

Reactant 4

HCID 1140TolueneHCID 62657Potassium Phosphate, TribasicHCID 52330122-Ethenyl-4,4,5,5-tetramethyl-1,3,2-dioxaborolaneHCID 46739269tert-Butyl 4-(5-bromo-3-methylpyridin-2-yl)piperazine-1-carboxylate

Product 1

HCID 673806954-(3-Methyl-5-vinylpyridin-2-yl)piperazine-1-carboxylic acid tert-butyl esterYield 46.3%

Reagents, catalysts & solvents 2

HCID 11556747Bis(tricyclohexylphosphine)palladium(II) DichlorideCatalystHCID 962WaterSolvent2×

Procedure

To a mixture of 4-(5-bromo-3-methylpyridin-2-yl)piperazine-1-carboxylic acid tert-butyl ester (3.3 g), bis(tricyclohexylphosphine)palladium(II)dichloride (332 mg), tripotassium phosphate (11 g) and vinylboronic acid pinacol ester (3 g) were added toluene (27 mL) and water (1.4 mL), and the mixture was stirred with heating under reflux for 8 hr. The reaction mixture was cooled, water was added, and the mixture was extracted with ethyl acetate. The organic layer was washed with saturated brine, and the solvent was evaporated. The obtained residue was purified by column chromatography (hexane:ethyl acetate) to give 4-(3-methyl-5-vinylpyridin-2-yl)piperazine-1-carboxylic acid tert-butyl ester (1.3 g). The obtained 4-(3-methyl-5-vinylpyridin-2-yl)piperazine-1-carboxylic acid tert-butyl ester (1.3 g) was dissolved in ethanol (20 mL), 5% palladium carbon-ethylenediamine complex (600 mg) was added, and the mixture was stirred at room temperature for 8 hr under hydrogen atmosphere. The mixture was filtered through celite, and the solvent was evaporated from the filtrate to give 4-(5-ethyl-3-methylpyridin-2-yl)piperazine-1-carboxylic acid tert-butyl ester (870 mg). The obtained 4-(5-ethyl-3-methylpyridin-2-yl)piperazine-1-carboxylic acid tert-butyl ester (870 mg) was dissolved in chloroform (2 mL), 4N hydrogen chloride/ethyl acetate (1.5 mL) was added, and the mixture was stirred at room temperature overnight. To the reaction mixture was added 1N aqueous sodium hydroxide solution (7 ml), and the mixture was extracted with chloroform. The organic layer was washed with saturated brine, and the solvent was evaporated to give the title compound (441 mg).

Workup

  1. temperaturewith heating
  2. temperatureunder reflux for 8 hr
  3. temperatureThe reaction mixture was cooled
  4. extractionthe mixture was extracted with ethyl acetate
  5. washThe organic layer was washed with saturated brine
  6. customthe solvent was evaporated
  7. customThe obtained residue was purified by column chromatography (hexane:ethyl acetate)

Sources & evidence

ORD record
ord-90bf6e436b024cf4939fc974ee438a4b
Source dataset
uspto-grants-2014_08
Patent number
US08816079B2

Reaction notes

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